Notes on Pennsylvania Railroad Operation and Signaling

With a description of the Indianapolis Division in 1950


Contents

  1. Introduction
  2. The First Block System in America
  3. The First Interlocking in America
  4. Train Rules
  5. Semaphore Signals
  6. Position-Light Signals
  7. Cab Signals
  8. The Indianapolis Division, 1950
  9. References and Notes

Introduction

The Pennsylvania Railroad Company was organized in 1846 to provide a better alternative to the Main Line of Public Works of the Commonwealth of Pennsylvania, whose roots go back to the 1820's and include the first significant modern railway in the United States, the Philadelphia and Columbia. It ended in the Penn-Central merger of 1986, but by that time impossible conditions of business, added to the failure to attract the kind and quality of people that had built and maintained the company, a failure that was common to the whole railroad industry, had reduced the company to a shadow of its former self. Management by engineers for the benefit of the public was replaced by management by incompetent lawyers and accountants with negligible engineering knowledge, and operation by men and women who devoted their conscientious and responsible efforts to a lifetime career with the company by casual, selfish laborers who would be treated by the company as they, in turn, treated it. This terminal decline set in after about 1950. Collapse occurred not long after the merger, followed by government ownership in 1976.

The PRR was a Philadelphia institution, but was always honorable and reputable, unlike that corrupt and nasty city, the one in America for which "might have been" is most poignant. The PRR was a rare demonstration that a public service could be provided by a private company organized to give an adequate return to its investors. It was a railroad company, not a coal company or a steelworks with attached railroad. By its nature, it owned a great deal of valuable property, but this was always used for transportation purposes, not speculation. To its investors, which included many individuals, it always provided an adequate return. It was one of the earliest railroad companies with a pension scheme, and compensation to its employees for injury and death. All of this was primarily due to management by engineers and career railroad men, a custom begun by J. Edgar Thomson (President, 1852-75), an outstanding Civil Engineer, and one which was seldom ignored until the later years. The practices which made the PRR great have now vanished completely from American industry, especially from those that provide a public service.

It is necessary to know these facts to understand why the PRR was a leader in all phases of railroad engineering. Not just a consumer or user, but an originator and developer, taking an active role in bringing new practices into use. The company's role in steam locomotive development is well-known, from the standardized classes of 1867 to the duplex drives of the latest days. Overseas developments, such as track tanks, were noted and adopted where advantageous. The introduction of steel rails, steel rolling stock, and even the American steel industry itself owe much to the PRR. Air brakes originated on the Pennsylvania, and George Westinghouse put his works near the line. The Pennsylvania cooperated with Westinghouse on all his railway innovations, usually serving as the initial test bed. The first air-braked train was the Steubenville Local out of Pittsburgh. In later days, train radio and cab signals originated on the PRR, and advances were made in electrification and electric locomotives. Indeed, the company made the dominant contribution to many aspects of operation and signaling, including train rules, the block system, automatic block signals, and interlocking, either adopting the systems from overseas, or developing them independently. No other railroad company comes even close in this effort, especially before 1900.

In this paper, I wish to record some of the history of the Pennsylvania's contributions to railway operation and signaling, and try to establish what really happened, the reasons for it, and the outcomes. Most railroad historians concentrate on the business and human aspects of the industry, and rather uncritically mention engineering and other technical factors as if they were simple and well-known, which they most definitely are not. In many cases, the same sources and traditions are always quoted with no investigation into their accuracy, and no understanding of the matters. Several examples will be mentioned here.

For a general history of the PRR, References 1-5 should be consulted. The best source up to 1945 is probably Burgess and Kennedy. Reference 5 includes later history, and is specially pertinent to the discussion of the Indianapolis Division. References 6 and 7 are popular histories concentrating on post-WW II years. Photographs and illustrations pertaining to the subjects of this paper are pointed out in the References.

Cautions About American Railroad History

Much of the technical history of American railroads is fable and folklore mixed with occasional fact. The early United States never looked back on its history with much pleasure, and old things were rapidly destroyed and forgotten. One can instance the midwestern canal network, the Greek Renaissance buildings of Philadelphia, and even the Main Line of Public Works, which had vanished from the public memory by 1875. Already at the Centennial Exposition of 1876, and much more strongly at the Columbian Exposition of 1892, a desire to remember the past became evident. When a search was made for old things, very little, if anything, was found. John Bull, pride of the Smithsonian, was represented by a wheel and some fragments of iron found behind the roundhouse when a search was instituted. From this, and some old prints, a locomotive was constructed for the Centennial, which was further embellished for the Columbian. In 1927, at the centennial of the Baltimore and Ohio, Tom Thumb was built when no drawing or other representation was known, purely on imagination. It is doubtful if this construction looks anything like Tom Thumb, being much too large and driven incorrectly, and probably owing most to folk memories of the Grasshoppers. The famous paintings of early railway events made for the Columbian Exposition are artist's interpretations, not representations from life, and mostly show the later recreations, not the originals. They seem to be taken today as accurate representations of the actual events.

When it comes to signals, absolutely nothing remained of the early days. Some items were constructed from extant drawings, others from imagination. Drawings were made that were patently erroneous, existing only in the artists' imaginations. This material has now been assimilated into the official history of American railway signaling.

Much history has been taken from the latest recollections of participants in the events, but only after the lapse of thirty or more years, and usually after the decease of the protagonists. The confusion of memory in these conditions, and the natural tendency to magnify one's own contribution leads to a mixture of truth and error that is hard to untangle. Where it is possible to refer to contemporary documents, the chance of correctness increases dramatically.

When someone asked why and how this or that had originated, and the details were not known, it was customary to think up a droll story and attribute the practice to some definite but imaginary origin, a time-honored method for the creation of fable. For example: the use of sand was suggested by a plague of grasshoppers; the communicating bell was invented by a conductor in a dispute with an engineman; trains on the Chicago and North Western ran on the left-hand track because it was built with English money; and Charles Minot initiated train orders when he used the telegraph to advance his train against a delayed superior train in a fit of annoyance. He might well have done this, but he and Superintendent McCallum were telegraph enthusiasts, had just bought the telegraph line from a bankrupt telegraph company, and were encouraging its use for this purpose all the way to Dunkirk. There is usually more to the story than the epigram.

The First Block System In The United States

The Pennsylvania inherited the first block system established on an American railroad when it leased the United Railroads of New Jersey in 1871. The Camden and Amboy Railway Co., part of this association, was the main rail link between Philadelphia and New York. One part, the original Philadelphia and Trenton, ran from Kensington (Philadelphia) to New Brunswick via Trenton. Locomotives had been able to cross the Delaware River bridge at Trenton since 1840. Another part, the original C&A, ran from Camden, on the Delaware opposite Philadelphia, to South Amboy, on the Raritan opposite Staten Island. A short connecting track from Trenton to Bordentown joined the two lines to form a through all-rail route from Philadelphia to South Amboy, from where ferries steamed to New York over 27 miles of water. These roads, chartered in 1830-32, were some of the earliest steam railways in the United States, and were all in operation by 1840. The important Delaware River Bridge at Trenton, a timber Burr arch built by Lewis Wernwag in 1804, and strengthened to carry locomotives, was widened in 1851 to accommodate two tracks. An iron truss replaced the timber arch bridge in 1874. The companies also operated canals in the area, such as the Delaware and Raritan, and ferries across the Hudson.

The credit for introducing not only the block system into the United States, but also the interlocking of switches and signals, belongs to the civil engineer Ashbel Welch (1809-1882), who was educated at the Albany Academy under Joseph Henry. After graduation in 1826, he began as rodman on the Lehigh Canal, rising to chief engineer of the Delaware and Raritan canal in 1835, and of the Belvidere - Delaware Railroad. In 1844 he visited England for the first time, and thereafter kept in close touch with British engineering practice. In 1845, he consulted with Joseph Henry on the application of telegraphy to railroad operation. While with the Chesapeake and Delaware canal in 1853, he collapsed from overwork, and spent the next few years recuperating in England. He was named vice-president of the Camden and Amboy Railroad in 1862, where he worked for the consolidation of all the railway and canal interests in New Jersey. When this was achieved in 1867, he became president of the United New Jersey Railroad and Canal Company, and served until the leasing of the property to the Pennsylvania Railroad in 1871. His engineering activities continued, among which were the design of an early steel rail, and design of wheels and trucks. He was named Vice-President of the American Society of Civil Engineers in 1880, and President in 1882.

There was a serious accident on the Philadelphia to Trenton line on 7 March 1865 at Bristol, Pa., 10 miles south of Trenton, when a Washington to New York express ran into the rear of a Kensington to New York 'owl' train at 2.30 am [Ref. 9]. The owl train had been delayed waiting for an oil train to get into the clear. Five soldiers going home on furlough from the war in the owl train, and the fireman of the express, were killed. Appalled by the accident, Mr. Welch called in his Superintendent of Telegraphs, Robert Stewart, and set in motion a plan to establish the block system on his own road, being well aware of its growing acceptance in Britain. Mr. Welch gave a report on the block system to a conference of railway officials at New York in October 1866, and a paper by him was also published in the Journal of the Franklin Institute. Later, in 1869, Mr. Welch was in England for the purpose of procuring an interlocking plant for the Top-of-the-Hill junction near Trenton, which was put into service in 1870.

The block system was established between Kensington and Trenton, about 30 miles, in 1865, according to Mr. Welch himself in the 1866 report [Ref. 10]. Mr. Stewart's recollection 25 years later that this happened in 1863, often quoted, is erroneous, as is the claim that Welch was unaware of the British block system [Ref. 11]. Mr. Stewart may well have been unaware of it, but Mr. Welch certainly was not. There were seven block stations (six blocks) in this first segment, so the block length averaged 5 miles. Telegraph offices in the stations were used as block stations. Later, the block system was extended to New Brunswick, 26 miles further north. After the New Jersey Railroad and Transportation Co. joined with the Camden and Amboy to form the United Railroads of New Jersey in 1867, the block system was further extended from New Brunswick to Jersey City, where the NJRR&T had its terminus at the Cortlandt Street ferry, in use since the 1850's, and much more convenient than South Amboy. The block system was interrupted by short stretches through Jersey City, Newark, Elizabeth, and New Brunswick, where there was street running at slow speeds. A good deal of confusion over the history of the block system has existed [Ref. 12].

The U.R.R. of N.J. was connected with other railways in Philadelphia only through the streets of the city until the 8-mile connecting line from Frankford Jct., 4 miles north of Kensington, to West Philadelphia (Mantua) on the Pennsylvania Railroad was completed in 1870. After the block system had been extended over this line, it covered about 90 double-track route miles in all. Mr. Stewart stated that the absolute block was used (at least for passenger trains), in which no train was admitted to a block before the previous train had left the block. The block signals had two aspects, clear (white), and stop (red). The status of the block was remembered by means of a pegboard. A peg was inserted when a train entered the block, and withdrawn when the signalman in advance sent the message 'out.' The suggestion for the use of a physical reminder of block occupation was Mr. Welch's, and it was also a principle of the British block system. The signals were normally at stop. A train would whistle for signals 1/2 mile from the station. The operator would hold the signal clear (if appropriate) until the train passed, then let it return to stop by gravity. When the train had passed, it was reported by telegraph to the stations on either side.

After the lease of the United Railroads of New Jersey for 999 years by the Pennsylvania in 1871, the block system was retained, but not immediately extended. In 1873 a modified block system was tried on the Pittsburgh Division. The Pennsylvania introduced a third, green, aspect to the block signal to facilitate permissive blocking, which was held to be essential because of the length of the blocks. Block system rules appeared in the 1874 Rule Book in anticipation of the wider use of the block system. The rules and the signals were similar to those used on the United Railroads of New Jersey, except that the pegboard was abolished. The system, as fully developed by 1900, is described in Chapter I of B. B. Adams, The Block System.

The Centennial Exposition in 1876 at Philadelphia was the stimulus for a general adoption of the block system on the main lines of the Pennsylvania Railroad, which took place in the fall and winter of 1875-6. The blocks were from 6 to 10 miles long. The block stations were housed in attractive octagonal wooden signal cabins (towers) on square bases built expressly as block stations. Many of these lasted a long time, and appear in many photographs. The signalman was on the second story of the 15'-high buildings, with the signal on a lattice bridge spanning the tracks. The signal, called a banner box signal, different from those devised by Welch and Stewart, sat at the center of the bridge, governing both directions with one oil lamp shining through a circular aperture of 22" diameter with a white sheet-iron conical rim 33" diameter and 3" deep, bordered with black next to the aperture. The wooden signal housing was 5'6" high over the chimney top, 2'3" wide, and 1'5" deep, painted black outside, white inside. The signal bridge was soon dispensed with, the banner box signal being mounted on the signal cabin itself. Where there was no signal cabin, the signal could be mounted on the roof of a station building, for example.

A green glass shutter and a red cloth shutter in front of the lamp, on both sides, could be raised independently by ropes by the signalman in the tower. Normally, the red cloths were down, showing red in both directions, and the green glasses raised and fastened. To permit a train to pass when the block was clear, the red shutter was raised and held by hand until the train had passed. If a preceding train was in the block, a train permitted to follow by rule under caution was admitted the same way with the green glass down. The use of red cloth instead of red glass was apparently a result of frequent breakage of the red glass. The green glass was apparently not exposed to danger enough to necessitate its replacement by cloth. As can be imagined, the red signal was not very bright, especially by day, and complaints were frequent. In fact, a good red signal was not really essential to stop a train. If the engineman did not see the easily visible white signal (the bare lamp flame), he knew that something was up, and would approach with care. This is an early good example of the principle that a driver looks for the proceed signal, and if he does not see it, reacts with caution.

The Philadelphia, Wilmington and Baltimore installed the Pennsylvania block system on its lines in 1880, still using the banner box signal. When the PW&B was leased by the Pennsylvania in 1882, the block system was extended from Baltimore to Washington over the Baltimore and Potomac Railroad. The block system now was continuous from New York to Washington, from Philadelphia to Pittsburgh, and probably from Baltimore to Harrisburg on the Northern Central. The banner box signals were later replaced by semaphores as the US&S pneumatic automatic block was installed, and practically vanished by 1890. This continuous block system over long distances was unique in the United States for many years. Most other companies used the block system only over short distances where difficult operating conditions (such as congestion or tunnels) were encountered.

The banner box signal was replaced by the semaphore during the 1880's. The manual block semaphore showed not only white, Clear-block, and red, Stop, but also green, Permissive-block. A freight train could follow another freight train into a block on a Permissive signal. The green could also be given with a flag or lamp in case the semaphore had only two positions, which was true at first, until a 3-aspect lower quadrant signal was developed. There was a constant evolution of manual block signals, but the principles remained the same. When green for clear replaced white after 1917, yellow became the permissive color. Yellow with a round-ended blade over two reds side by side was the later semaphore Permissive-block aspect, green over two reds the Clear-block aspect. The semaphore signals are described in more detail below.

The Columbian Exposition of 1892 in Chicago was, like the Centennial in '76, a spur to the introduction of the block system, this time on the Erie. The Erie was an early user of the block system, but mainly on the busier eastern end of its system. The Erie block system used bell signals, as in England, and proved an excellent system. The Pittsburgh, Fort Wayne, and Chicago, the Pennsylvania system's western end, also had a continuous block system, but it differed from that on the Pennsylvania proper in that it used train-order signals as block signals, with somewhat different rules.

The Pennsylvania and the Erie handled the 1892 Columbian Exposition traffic safely and expeditiously. The Big Four, which pooh-poohed the block system, suffered a serious rear-end collision at Kankakee in September between two sections of a train. The New York Central System, also a block system skeptic, had serious rear-end collisions in 1889, 1890, 1891 (two), and 1893.

In the same period, the Pennsylvania had but one bad accident, in 1892 at Pittsburgh, described by Shaw [Ref. 13] on p 201f. I must disagree with Shaw's analysis, since the accident was caused by a signalman's clearing the block signal when he did not know positively that the block was clear. A similar accident on the Burlington at Western Springs, Ill. in 1912 was due purely to lack of clearance space in advance of a stop signal. These accidents show one fatal shortcoming of American block systems, that of not providing a definite clearance in advance of a home signal, and relying on flagging to stop a train that has been admitted to a clear block that is obstructed at the exit. The problem is mitigated by the use of distant signals to give notice of a signal at stop in time to halt the train. In Britain, the use of distant signals, in addition to providing a quarter-mile clearance space, was standard practice.

The 1874 and 1882 Rule Books do not explicitly prescribe a block record, but the operators may have used the train register mentioned in Rule 283; at any rate, a block record was certainly kept. There was no physical reminder of block occupancy except this record. The telegraphic signals prescribed are shown in the Figure. These signals imply that, before admitting a train to a block, the signalman requested the block status from the signalman in advance, not relying on a block record. This necessary practice for single track did not survive in later rules for double track, where the block record was sufficient authority to admit a train to a block.

American manual block rules, including the Standard Code, have always neglected the principle of acceptance, which is recognized in Britain. This principle is that the signalmen at the two ends of the block must cooperate in admitting a train to the block, even on double track with trains moving in one direction. In Britain, a signalman 'offers' a train to the signalman at the other end of the block by bell signals. If this signalman agrees that the line is clear, he answers, 'accepting' the train, and moving a switch that displays a signal in the first signalman's office that the block is clear. The two signalmen check each other in this system. In the United States, a train can be admitted to a block on double track if the written block record checks clear. Of course, the signalman does notify the signalman in advance that the train is coming, but this is too late if there is a problem. C. C. Anthony, the Signal Engineer of the PRR in 1895, himself makes the point in an article in the Railroad Gazette [Ref. 14] but was unable to convince even the higher authorities on his own road. The reason acceptance was not required was the fear that, in case of wire failure, the train would be held without reason at the first point. This seems a weak argument, since the train could be admitted under caution anyway. This is not just a theoretical detail; accidents have resulted from it. The Erie, by the way, required acceptance, at least until the Standard Code was adopted. On single track, control of the block must be obtained before a train is admitted to it.

On the Pennsylvania, the block system on single track was always an additional safeguard, backing up timetable and train orders. In fact, when communication failed with the next block station, trains were allowed to proceed on time table and train order rights (Rule 333). Additional safeguards were necessary to permit operation by block signals alone, and these were not generally present either in the layout of the signals or the rules. The necessary safeguards were, however, provided by continuous track circuits, or by the lock-and-block apparatus that was used by some companies (not the PRR) until track circuits were adopted. As we shall see, this also meant cab signals on the PRR, so the manual block system was always quite secure.

The 1882 Rule Book mentions "starting signals" in the definition of fixed signals, but no further mention of them is made. A starting signal is placed in advance of a home signal to give a clearance space. In British practice, a block cannot be reported clear while there is a train between the home and starting signals, but as soon as it has passed the starting signal the block can be reported clear (instead of waiting until it has passed the next home signal), assuring that a train encountering a home signal at stop unexpectedly can stop clear of an obstruction. In American practice, a starting signal allowed the train to clear the block, so a following train could be accepted. The 1874 Rule Book provides that a train must have advanced at least 100 yards beyond the home signal before the block can be reported clear. These rules generally admitted trains to an occupied block under a green signal, with provisions for time intervals and other safeguards. The block system was applied strictly to multiple tracks with a specified current of traffic - that is, to following movements only. No provision was made for the operation of trains in both directions on a single track solely under a block system at this time, but it was soon to come when additional safeguards were available.

The block system was originally called the "telegraphic block," suggested by William Fothergill Cooke in 1842 in England, in his book Telegraphic Railways. Before 1900, the term manual block became popular, in distinction to automatic block, in which the signals were controlled by the trains themselves rather than by signalmen communicating with each other. The status of the blocks came to be displayed to the signalmen by block instruments in Britain, which descended from the needle telegraphs originally used there. After Welch's pegboard system was given up, no physical evidence of block occupancy was used in the United States until illuminated track diagrams appeared. British signalmen communicated by single-stroke bells; American signalmen by the usual telegraph. Both British and American signalmen kept written block records.

In the United States, freight trains were almost always operated under permissive block rules, under which one freight train can follow another into a block at restricted speed after being cautioned. Although it would have been safer to maintain an absolute block for all trains, the length of American blocks would have made delays excessive. In Britain, blocks were less than a mile long in congested areas, and seldom more than a mile or two long anywhere on busy lines. American traffic was too sparse to justify such an expense on signalmen, and a five-mile block was considered a short one.

The block system created by Ashbel Welch was the first in the United States consisting of sequential blocks covering a considerable distance. The use of the telegraph for controlling movements at long tunnels and similar critical points was already well known. For example, the Erie used a telegraph block through the Bergen Tunnel. The idea at all such installations was not to allow one train to follow another into the tunnel until the first train had been reported clear at the other end by a telegraphic message. Thus, a sort of block was established, but this cannot be called a block system.

The First Interlocking In The United States

The term interlocking refers to the concentration of the control of signals and switches at a single point, with a means of ensuring that the switches and signals are operated in the correct order and without conflict with each other. Interlocking was introduced early in England, and was common by 1860. Like block signaling, interlocking was not used in the United States until it was introduced by Ashbel Welch. In fact, even important passenger stations used manual switchtenders until very late (indeed, to the end). Power interlocking, however, was invented in the United States in the 1870's, operated by hydraulic or pneumatic means.

The United Railroads of New Jersey installed the first interlocking in America, a 16-lever Saxby and Farmer frame, No. 905, which arrived in Trenton in October 1870 and was installed at Top-of-the-Hill near that station. The second interlocking, also by Saxby and Farmer, No. 2164, was installed by the Pennsylvania at the important junction of East Newark (Newark Jct.), New Jersey, in 1874, and was in service on 11 February 1875. These Saxby and Farmer plants were the reason that American signals and signal towers resemble their British prototypes, and that the semaphore signal became standard American practice, as it was in Britain. They had the slotted-post signals still in use in England, but all later signals were two-position lower quadrant arms that did not disappear inside the post when at clear. The installation at Newark was suggested by G. O. Howell, Principal Assistant Signal Engineer of the New Jersey Division as desirable in view of the coming Centennial Exposition, and was mentioned in the Scientific American magazine of April 1875. The Engineering News of March 1894 contained a retrospective article on this installation, with a track diagram and overall view.

For some reason, the East Newark interlocking came to be regarded as the first in the United States, but A. H. Rudd (see below) mentioned the 1870 frame at Top-of-the-Hill quite distinctly in his 1942 paper, and it is unlikely that he would be in error. The East Newark plant was the first on the Pennsylvania Railroad, the Top-of-the-Hill plant first in the United States.

The upcoming Centennial Exposition spurred much interlocking activity as the Pennsylvania prepred for the event. It was decided to interlock several junctions, but Saxby and Farmer machines could not be provided on such short notice, so a couple of Toucey and Buchanan frames from the NYC&HR were borrowed and pressed into service. The feature, however, was the Burr hydraulic power interlocking at Mantua Junction. This machine had fatal faults, but performed well enough during the summer, well enough to convince George Westinghouse that power interlocking had a future. He modified it to pneumatic control and hydraulic actuation, achieving rapid, solid action and indication. His frame was much better than competing all-hydraulic interlockings then available.

George Westinghouse established the Union Switch and Signal Company in 1882, as successor to the Union Signal Company of Boston, which he had purchased. Its factory was established at Swissvale, Pa., near Pittsburgh, close to the Pennsylvania Railroad line on which many of its products were tested and used. The Westinghouse hydraulic power interlocking system was succeeded by the hydropneumatic in 1884, which interchanged the roles of air and fluid, and the electropneumatic in 1891. The electropneumatic interlocking found acceptance worldwide. In this system, the interlocking was done by a miniature mechanical locking frame, with solenoid valves to operate the pneumatic cylinders on switches and signals. The United States led in the development of power signaling, first with the electropneumatic system, and later with all-electric operation, after 1900.

US&S practice in interlocking was founded on the practice of the British firm of Saxby and Farmer, who had developed the very best in mechanical interlocking. In fact, Westinghouse hired away designers from this firm, and licensed its patents as well. Saxby and Farmer introduced the important principle of latch locking, in which the interlocking worked on, and was operated by, the latches for the switch and signal levers, not the levers themselves. A signalman who made a mistake could not then exert excessive force to move a lever improperly, since he could not get the latch off. Neglect of this principle a hundred years later caused the crash of at least one DC-10 when a cargo door handle was forced to seem closed when it was not, against a safety mechanism that restrained the handle itself, not its latch.

An interlocking plant of the 1880's, at a junction, end of a siding, or where the number of main tracks changed, appeared considerably different from later practice. High semaphores governed only main-track, through movements, and were also block signals. Each arm corresponded to a certain route. Where arms were one above the other, the top arm governed the leftmost route, and so on. The high-speed route was not necessarily the top arm. Enginemen had to be familiar with the routes that corresponded to each arm. There were no dwarf signals for reverse or switching movements. All such movements were made at restricted speed under hand signals. Crossover and junction switches were interlocked with the signals so that the signals could not be cleared for an incorrect or slow-speed route, however. Hand-thrown switches with the simplest switch stands and no targets were frequently seen, even within interlocking limits. The keys to these switches would be kept by the signalman. There were, of course, no track circuits, and distant arms were not to be seen below the home signals.

US&S made use of the closed track circuit train detection principle of William Robinson, demonstrated in 1872 on the Philadelphia and Erie, then already part of the Pennsylvania system, acquiring it in 1882 with the Union Signal Company, along with rights to the clockwork banner signal that had been developed by Oscar Gassett in Boston [Ref. 15]. Clockwork automatic signals were installed on the PRR between Altoona and Gallitzin in 1881, one of the few examples of this kind of signal outside of New England. There were 29 type 'C' signals on the 12 miles of heavily graded double track leading up to the Horseshoe Curve. It is not recorded when these signals were taken out of service, but they lasted at least until 1885, and probably until electro-pneumatic block signals arrived a few years later. A photograph in Alexander [Ref. 4, No. 102] taken in 1885 clearly shows an example at the Altoona station. The two signal heads side by side are probably home and distant signals. Apparently, they did not supersede the manual block, but supplemented it. The track circuit made reliable automatic signals possible, and is, therefore, one of the most important contributors to railway safety, along with the block system and interlocking. The first Westinghouse pneumatic semaphore, track-circuit automatic block signals appeared in 1883, and were tested in a small installation on the Fitchburg Railroad. They were not used on the Pennsylvanis until late in the decade.

By 1884, 660 Saxby and Farmer levers were installed on the Pennsylvania, out of 2112 levers total supplied by the US&S Co. in the United States. The East Newark interlocking was followed by an early Westinghouse pneumatic interlocking plant at West Philadelphia (Mantua), which handled the traffic to the Centennial Exposition in 1876. A trial installation of automatic block signals and hydropneumatic interlocking was made in the Pittsburgh area, between East Liberty and Wilkinsburg, close to the US&S factory, in 1884. There were 12-lever interlockings at the two points named, 2.5 mi apart, on a four-track line, with 20 blocks in all. This system used closed track circuits and solenoid valves to operate lower-quadrant semaphore signals. Further interlockings at 14th and 17th Streets in Pittsburgh extended the system 3.75 mi westward on 8 August 1888. After this, installation proceeded in 1891 with electropneumatic machines, and the system was eventually installed between Jersey City, Philadelphia, Wilmington, and Paoli, in addition to the Pittsburgh division, and its signals and towers appear in many photographs and woodcuts of the period. It should be noted that the system required compressed air to be piped along the line. By this time, interlockings had assumed a modern aspect, with dwarf signals and signals for all routes.

Lines West, apparently, never had electropneumatic interlockings. All power interlockings there were all-electric, with switch and signal motors.

Distant signals were generally used in connection with interlocking and the automatic block system, although early phtographs of them are rare. A distant signal would be placed at some distance from the locations usually the subject of photographs, so this is not surprising. It was easy to combine interlocking and the block system, so most interlocking plants were also block stations. On four-track line, where all tracks were signaled, the two center tracks were generally the freight tracks, and the two outer tracks passenger, for access to platforms. Earlier, sometimes only the passenger tracks were signaled.

Train Rules

The earliest PRR Rule Book of which I am aware is the edition of 1857 [Ref. 18]. It differed little from those of other principal companies, except perhaps in being rather more straightforward and uncomplicated than most. By this time, it was good practice to collect the rules for the operation of the railroad in a book for general distribution, so that there would be no uncertainty as to what was required. Although various kinds of rules were included, some of a general nature, the core of the book was the rules governing signals and the running of trains, the train rules, which are surprisingly few and concise.

A lamp or flag moved up and down was the hand signal to proceed; moved from side to side it was the signal to stop. One whistle sound meant apply brakes, two meant release brakes. These are exactly as they are now, and so familiar it is hard to realize that in 1857 these things were not standardized, and on many roads the signals were precisely the opposite. On the Philadelphia, Wilmington and Baltimore in 1854, one sound meant release, and two apply brakes. On the New York and New England Railroad in 1880, the proceed and stop signals were the reverse. In this early Rule Book, many things are recognizable as what became standard practice, but it should be remembered that this is only because the Pennsylvania customs became adopted as standard later; they were by no means the standard at the time.

White is the color for safety, and red the color for danger. As was common in the United States at the time, blue was the color of caution--a blue flag by day, and a blue light by night. However, in this Rule Book a green light could also be used for caution. It happens that blue lenses block so much of the light of an oil flame that blue lanterns are very dim. Green lenses are much better, especially a kind of yellowish green, and apparently this was being recognized. Green was slow in being adopted as the caution color in the US, although it had been standard in Britain since 1841, and the fact was known in America.

Trains carried a white headlight and two red tail lamps by night. By day, a freight train carried a red flag on the right-hand side of the last car as a marker (italicized in the Rule Book, as apparently a new term), so that the engineman could determine if he had all his train with him. A red tail light was carried through the Allegheny (Gallitzin) tunnel as well. Every passenger train had to have a communicating bell cord on each car. Though it was emphasized that the bell cord was indispensable, freight cars had to be handled directly behind the engine in a mixed train, which would have made this impossible. The engine bell was the signal "for passengers to take their seats." The conductor would ask that it be rung by two tugs on the communicating cord, then one tug would signal the engineman to start the train. Passengers were forbidden to ride on the car platforms when the train was in motion.

One long whistle sound was made approaching stations and grade crossings. Repeated brief sounds was an alarm to cattle. One shorter sound was the call for brakes, two to release the brakes. Three sounds indicated that the engine was about to back, and four recalled a flagman. Some of the later whistle signals can be detected here.

A very important signal was a red flag carried at the front of the engine. This showed that a train followed with the same rights as the train carrying the red flag. This was called "flagging for a train" and allowed a following train to proceed behind a regular train. It was the only way available to expedite the movement of an important extra train. The practice was almost universal on American railroads. In fact, it was sometimes much more elaborate than on the Pennsylvania.

The authority for running trains was the Time Card or time table, which gave the scheduled times of the regular trains, and the stations at which they were to meet on single track. Trains were expressly forbidden to leave before the times given in the Time Card. It should be understood that this is a perfectly safe way to operate single track, but it is severely affected by delayed trains. Without some modification, even small delays can rapidly escalate into major delays and near-paralysis. The solution for this is to designate certain trains, or all trains in a certain direction, as superior to those in the opposite direction. A superior train does not wait when an expected train is not found at the station where it is to be met by time table, but proceeds expecting opposing trains to keep clear of its time, waiting on a siding for it. On the PRR, a superior train can do this so long as it is not twenty minutes or more late. When it becomes twenty minutes late, it becomes an irregular train, and its rights evaporate. That means that an opposing inferior train waits until the expected train is twenty minutes late, and can then proceed regardless of it.

An irregular train can proceed only behind a flagman, at not more than four miles per hour, unless the way could be seen clear ahead at least a quarter-mile. The delayed train would do this until it encountered the expected train, which would also be running easy and looking out. Then, the train closest to a siding would back to that siding and the trains would meet. After this, the delayed train could then proceed normally, perhaps even recovering its rights. The rule that when trains met between stations the train closest to a siding would back to it might be interpreted by the uninitiated that trains usually met this way, careering along until smoke or headlight was sighted, but this is far from the case.

Freight trains had to wait for opposing freight trains 30 minutes, and there was no "preference of road" as with passenger trains. They could not proceed against a passenger train, however late it was, and sat on the siding until an expected passenger train showed up. They had to be in the clear 20 minutes before the passenger train was due. These rules only slightly eased the problem of delayed trains, and on a bad day it is easy to see that most trains would be creeping along behind flagmen.

An interval of one mile, or five minutes, was to be kept between trains in the same direction. Employees by trackside would indicate the number of minutes since the last train by the corresponding number of arm motions. When a train was stopped between stations, a flagman would go back 600 yards to stop following trains. When recalled, he would leave an "exploding cap" on the rail. There was no mention of fusees. A train could not follow a passenger train from a station until 10 minutes had elapsed.

A speed of no more than 10 mph was prescribed over bridges, and steam was not to be used while crossing them. Switches were negotiated at 4 mph. Irregular trains could not exceed 20 mph in any case. All ballast and wood trains were irregular.

An important rule states that all messages affecting the safety of trains are to be in writing. The telegraph is not mentioned, but it was definitely in use at the time. If a regular train was not to run, this information was transmitted to all stations by telegraph, and similar actions were probably taken in other circumstances. However, there was not yet any prescriptions as to transmission and delivery of such messages.

Operation of a single track by time table, in the manner just described, is tolerable if the traffic is light and slow, as it was in the United States before the Civil War. Heavier traffic and increased speed had already caused some strains in the 1850's, contributing to the first really serious accidents to occur in the country. It should be remembered that more serious accidents were caused by mechanical failure, such as the breakage of rails, wheels and axles, by the collapse of bridges, by obstructions in the road and vandalism, than ever by operational failures, such as collisions and misplaced switches. The main stimulus for improved methods of operation and signaling is an increase in line capacity and efficiency. Safety, however, is a necessary requirement.

The Civil War placed unprecendented demands on railroads, causing a search for ways to increase line capacity. Adding a second track much more than doubles line capacity when operating by time table, since it not only allows more trains to be run, but reduces the delays to each train. A single track with adequate siding capacity (seldom provided at the time) could handle perhaps as many as ten trains a day in each direction, with any unusual difficulty resulting in chaos. A double track can handle perhaps fifty trains a day in each direction, though equipment and terminal difficulties begin to govern at this traffic density. In addition, one track can temporarily be used in both directions in case of damage or repair to the other. After the Civil War, the Pennsylvania main line was mainly double track, and this was also true of most other lines of heavy traffic.

Double track is expensive, and takes time to construct. The use of the telegraph, which by that time paralleled most railroads and had become more or less reliable, proved able to reduce delays on single track by giving notice of delayed trains, and allowing the running of extra trains with dispatch. This was to develop into the Train Order method of operation, but as yet was primitive and subject to dangerous error. It could, however, double the traffic that a line could handle almost instantaneously, at little extra cost.

A second method, instituted by Herman Haupt when a telegraph was not available on a certain line in Maryland, was to dispense with the time table, and run trains in convoys, in which the line was devoted to trains in one direction only for a period of time. Eight or ten trains could follow one another across a division in four or five hours, then the direction of traffic could be reversed as those locomotives returned with an equal number of trains. This also more than doubled the capacity of the line.

After the Civil War, not only was steel adopted for rails and the manufacture of locomotives and rolling stock, but the experiences of the War led to the less evident, but more significant, changes in operating procedure. We have already mentioned the introduction of interlocking and fixed signals, but there were also radical changes in Train Rules.

The Rule Book of 1874 eliminated all the rules designed to accommodate delayed trains in the timetable system, making it the first modern rule book. Instead, delayed and extra trains were to be handled by telegraphic orders. The method of using train orders prescribed by this Rule Book became, in all essential points, the method set forth in the Standard Code of Operating Rules adopted by the Standard Time Convention in 1889. Extra trains, those whose schedules were not included in the time table, were handled by two methods. The first, essentially a throwback to timetable operation, was to run the additional train as a section of a regular train. If an engine carried green signals, it meant that a train with the same rights was following, just as the red flag meant in earlier years. Sections could only be created by proper authority (earlier, anyone could put a red flag on an engine), and provision was made for protecting following sections when the green signals were taken down. The second was to operate extra trains by train order. In this case the extra train itself carried the white flags, which identified it as not a regular train, to avoid misidentification. The term 'extra' now acquired a definite meaning, and the older term 'irregular' fell out of use.

The Pennsylvania was probably the first to use the modern way of running sections and extras, and it was also the first to give up the practice many years later. Creating sections, and displaying green or white flags, was eliminated by the Pennsylvania in the 1930's, because it was unnecessary now that all lines were either under a block system, or were operated at restricted speed. It is possible that passenger extras carried white flags for a while after they were eliminated for freight extras, so they could be distinguished from regular trains. All freight trains were run extra. They may have had time schedules for traffic purposes, but had no time table rights. The block system makes it possible to operate passenger extras at the same speed as a regular passenger train, which was not generally true with other companies. Therefore, neither sections nor train signals were necessary, and their elimination made a great simplification in train operation.

The method of transmitting a train order is given in Rule 96 of the 1874 rules:

96. All special orders for the movement of trains must be given in writing, addressed to the conductor and engineman, and signed by the division superintendent. If sent by telegraph, the operator receiving the order must immediately enter it in the order book and repeat it back. When the division superintendent responds that the order is "O. K.," he will prepare two copies, and deliver one to the conductor and one to the engineman. They must compare their copies with the original order in the book, which they must sign, and must not leave the office until the operator repeats their signatures to the division superintendent, and he replies that the order is correct. Train orders must have written on them "correct," the name of the operator, the office, the date, and the time they were made "correct."

Conductors and enginemen must not run on any order that has not been made "correct," (after they have signed for it,) or that has been erased or altered in any way, or that they do not fully understand.

The superintendent always delegated his responsibilities to a train dispatcher, who would actually compose and transmit the order, and keep a book with all the orders in it. The centralized control of a division by a single dispatcher was an important innovation. In the 1882 Rule Book, this rule has been split into Rules 105 and 285, which nearly duplicate each other. The only change is that all copies of the order must be made in manifold, instead of the operator's writing them in a book. Apparently, carbon paper came in between 1874 and 1882, as did fusees for flagging. The rule also has a pernicious addition, that the operator must read the order aloud to the conductor and engineman. It would have been better to have the conductor and engineman read the order to the operator. This addition was removed in the Standard Code, and the term "correct" was replaced by "complete." This is the origin of the '31' order, the basic train order. The most important elements lacking in this rule are an order number, and the requirement that an order be sent in the same words to all who are to execute it. The 1882 Rule Book scatters rules on the same subject among instructions to different classes of employees. Neither rule book gives standard forms for orders, which had been found very desirable, and appeared in a few other rulebooks of the time.

The signal color green (for caution) is prominent in the Pennsylvania rule books. It is used in the block system as the Permissive color, as signals for a following section, and as markers. Most other American railroads made do with red and white alone. Blue on the Pennsylvania was used in the same way as in the Standard Code, to protect workmen working on equipment. On the Old Colony, blue was the train order signal, and on most other roads was the caution color.

The Pennsylvania whistle signals, such as the long-long-short-short for grade crossings, appearing in the 1874 Rule Book, were mostly preserved in the Standard Code. Long and short sounds were now prescribed, instead of simply a whistle sound. The green-and-white signal for a flag stop was also a PRR practice. One can find many such examples in the Standard Code.

Robert Pitcairn of the Pennsylvania was probably on the first Rules Committee of the American Railway Association, earlier the Standard Time Convention, that put together the Standard Code of Train Rules that was adopted on 14 April 1887, and he was probably also largely responsible for the PRR 1874 Rule Book. It would be good to know the men responsible for these developments, but apparently this has been forgotten. The 1882 Rule Book actually is a step back from the precision of the 1874 edition. Apparently some bureaucratic mind liked the idea of constructing rules! The Standard Code included good ideas from other sources, and introduced a consistent system based on fundamental principles. It was quickly adopted by the PRR, although the Pennsylvania, like other companies, made its own modifications to the Standard Code. These amounted mainly to eliminating the parts it did not find necessary, and extending the block system rules to suit its unusual conditions, not in changing the principles established in the Code. The status of the rules at the time of the classic Rule Book of 1941, which, in later editions, continued into postwar years, will now be described. It is operation under these rules that will be most familiar to the reader who observed the postwar PRR.

The Pennsylvania had no Clearance Card Form A, which most other road delivered with train orders to ensure delivery of all orders to the proper train. It was not needed, since the signalman was permitted to clear the block signal on making positive identification of a train and finding that it was not the one addressed by the orders. There were other clearance cards, however: Form C for signals, Form CS for cab signals, and the frequently-used Form K for manual block signals. Form K was issued to trains to permit them to pass block-limit stations. The Clearance Card on the Pennsylvania was not an invoice for train orders, but reverted to its original use in permitting a train to pass a signal that, for some reason, could not be cleared.

There were only '19' orders on the Pennsylvania. The block system was relied upon to render any errors of delivery harmless. Train orders, and Form K, could be delivered to train crew members by telephone, as to an operator. The train order signal was not a semaphore, but a yellow flag or yellow lamp displayed in a prescribed place. The block signal at stop was relied upon to slow or stop the train for orders. After the train-order signal was acknowledged by the engineer by whistling, the block signal would be cleared, and the delivery could be made without stopping the train. When position-light signals were installed, the train-order signal became a flashing illuminated 'O' displayed on the signal post. An operator was usually called a signalman, since he had block duties, and usually operated a block signal.

It has been said that the Pennsylvania did not depend on accurate time in train operation. This is untrue, since all the Standard Code provisions for clearing trains are retained, as well as the forms of time orders (Form E). Standard clocks were provided, and time had to be checked before starting a run. It is, however, true that extensive use was made of moving trains by signal indication alone on single and double track, in which times are not involved. In such territory, the timetable could even permit a train to leave certain stations early when their work was completed, provided only that they did not leave before their arrival times (to protect the advertised times).

The manual block system rules were not a rigorous as British block rules. In particular, the exact method of knowing that 'the block is clear of all trains, and no other train has been given permission or a signal to enter the block.' A block record was kept at each station, showing the times trains were admitted to and cleared the blocks on either side. Signalmen would communicate by telephone with the signalman at the other end of the block.

On double track, it seems (by Rule 319) that the signalman could admit a train with the current of traffic on the strength of the block record alone, giving the signalman in rear the time the train left the block, and the signalman in advance the time the train entered. Under British block rules, a signalman must obtain the permission of the signalman in advance before admitting a train to a block. This is the principle of 'acceptance,' mentioned above. To realize the importance of the British requirement, consider a sleepy signalman who admits a train to a clear block and records it in the block record. Then, he inadvertently falls asleep, awaking with a start some time later when an approaching train whistles for signals. He looks at the block record, which shows the block is occupied, but it is much later than the time the preceding train should have cleared. He supposes that he forgot to make the record, due to his sleepiness, so he fills in a likely time and clears the block signal. He does not know that the preceding train has suffered a hotbox and is creeping along in the block, so a rear-end collision is likely unless this train is being properly flagged (the most one could expect is that fusees would be thrown off). Curiously, there is no rule that specifies action to be taken if a train is an unusually long time in the block, but one imagines it would only be good sense for the signalmen to confer with one another.

On main lines, it was usually economical to provide a sufficient number of block stations to avoid delays. Interlockings usually served as block stations, the interlocking signals acting additionally as block signals. However, on lightly-used lines, and at locations where a block station was needed only intermittently, the provision of a manned block station was out of the question, while a long block would severely restrict capacity. This dilemma was resolved by the creation of block-limit stations, beginning about 1920. These locations are unmanned block stations (and originally called "unattended block stations"), but have a fixed signal showing yellow and red (Rule 293), and a telephone booth. They are controlled by a manned block station named in the timetable. A train must stop at these points, unless authorized to proceed with a Form K or train order. A train without clearance had to contact the signalman controlling the block-limit station for permission to proceed. If the block was needed, trains also had to report clear when exiting the block. This was more work for the signalman, of course, but made it possible to reduce the number of open offices while retaining operating convenience. An 'approach block limit' fixed signal showing reflectorized black letters 'ABL' vertically on a yellow background was placed in advance of the block-limit signal. These fixed signals are shown below. The Rule Book did not show the colors of the Rule 293 signal, and I originally assumed that the horizontal bar was red. Al Buchan informs me that it was black, so the diagram shows this color, also white letters on a black background for the station name. The Rule Book also shows cutout letters. A train not holding authority to proceed had to reduce to medium speed at once at the ABL sign, and stop at the block-limit signal to telephone the control operator. It is interesting that the method of operation adopted in the United States after about 1975, with the end of scheduled trains, using the radio and track warrants, is very similar (in fact, identical in theory).

The signal lamp used for the night aspects of the block-limit signal worked on the principle shown in the diagram at the right. The lamp at the center was either a long-burning signal lamp, or an electric lamp. It showed red in one direction, and yellow in the other. The lenses were 5" in diameter, about 9' above the rail, and 9' from the track. 45° reflectors at each end of the reflector box guided the light to additional yellow and red lenses. If the lamp failed, all the lights went out. The dual-lens lamp with reflector was invented by E. A. Carter of the Chicago and North Western around 1895 to show the new caution signal of simultaneous red and green. There was no danger of the red lamp failing so that green alone was displayed erroneously. The PRR used this idea extensively, especially for the double red lights that identified the signal as manual block, originating with the Rudd-Rhea report (see below) shortly after the turn of the 20th century.

Where even this level of protection was unnecessary or too expensive, the Pennsylvania extended Rule 105 on the use of sidings to secondary tracks, which can be used at reduced speed without protecting against following movements, by permission of the signalman. A secondary track is a kind of long yard track, but with more regular movements, and sometimes a prescribed direction. The timetable gave the stations and mileages of a secondary track, with special instructions on its use as necessary. On most longer secondary tracks, the timetable might require protection, specify maximum speeds, normally 15 to 20 mph, but sometimes as high as 30 mph, and assign a current of traffic direction, if any. Secondary tracks normally did not have lighted switch lamps. This is, obviously, taking things back to a rather primitive level, but it is practical, and by carefully recognizing all the dangers involved and taking steps to minimize them, quite acceptable. Most other companies simply place such tracks within yard limits, and let it go at that. However, the idea of yard limits really cannot stretch so far with safety. Passenger trains did not use secondary tracks except in emergency, but there seems to have been nothing in the train rules prohibiting it.

Block-limit stations, secondary tracks, and the absence of green or white train signals made the Pennsylvania different from most other roads. The above discussion should clarify how these things were used, and how they were related to the Standard Code.

Semaphore Signals

A fixed signal is a signal of fixed location controlling the movement of trains. It may present a constant aspect and indication, such as a stop board at a non-interlocked crossing at grade, or the indication may change to reflect changing conditions. Such signals are accepted by the engineman without using his whistle to acknowledge them (two short sounds), since there is usually no one around to receive the acknowledgment. An exception is the train-order signal, which is acknowledged so that the signalman can clear the block or interlocking signal and make the delivery without stopping the train.

The first fixed signals introduced in the United States, in addition to flags or lamps fixed to a post, were the well-known ball signals derived from nautical tide signals, and rotating targets showing different colors. Semaphores were not thought of, and fixed signals of any kind were quite rare. Hand signals were relied upon almost exclusively. The station signal that showed when it was safe to enter or leave a station, gradually saw less use than at the beginning. The first impetus to fixed signals visible at some distance was the problem of open switches, which usually restricted trains to a low speed approaching facing switches. The Pennsylvania devised signal consisting of an elevated lamp and a red spectacle-form target, 18' and 15' 8" high, respectively, that rotated 90° as the points were moved to show the position of a switch at a considerable distance, and this signal received much praise from the profession. The lights it showed were red (switch open) and green (switch closed) for caution, not red and white.

Semaphore signals were introduced to the United States by the Top-of-the-Hill and East Newark interlockings, and by their use by the Union Switch and Signal Company. Previously, semaphore signals had been practically unknown, and even the term was unfamiliar in 1875. They were initially two-position lower-quadrant signals of British form, with square ends for home signals and fishtail ends for distants. Both were painted red with a white stripe, as in England, since yellow for caution was some years in the future. American semaphore blades became longer and thinner than British blades, and slightly tapered rather than parallel. The Pennsylvania eventually painted all semaphore arms yellow with a black stripe, as being most easily seen. Lines West was first to do this, in 1889.

The early signals had a single lens of red glass that was held before the oil lamp when the arm was horizontal. Eventually, distant signals had a bottle-green lens instead. The practice at the time in England was to use red for distant signals as well as for home signals, distinguishing them only by location and shape of arm, while green was the clear aspect. When the arm was lowered, the 'white' flame of the oil lamp could be seen directly. There is, by the way, no record of any accident ever having been caused by a missing or broken red lens. In fact, such lenses were sometimes made with a grid of wire within them, to prevent breakage from causing them to fall out completely.

Semaphore arms used by the Pennsylvania from the 1870's to the time of of the Rudd-Rhea report are shown in the figure. Arm A is typical of arms used in the 1870's and 1880's. The white stripe was not added to the blade until later, and appeared first as a black stripe on the back of the blade, since the white arm was not easily seen. In these days, one semaphore arm per route was used at an interlocking, stacked one above the other on a single mast. The leftmost diversion was on the top, the rightmost on the bottom. If several routes were possible, the most important might not be at the top, but somewhere in the crowd below. An engineer of a passenger train is said to have misread such a signal and run his express train into the turntable pit at Johnstown. Therefore, the principal route was assigned to an emphasized arm as shown at B. The double lights identified the arm by night. The top arm eventually was always assigned to the main route, the lower arms to less important routes, but this was not done until later.

These arms do not seem to have enough weight at the spectacle to return the arm to horizontal if the connections broke, and were helped to do so by the weight of the up-and-down rod or a separate counterweight. When it became regarded as desirable for the arm itself to return to horizontal, the spectacle was made heavier and placed at an angle to give better leverage when the signal was at clear, as in Arm D. The back of the arm is shown at E. By the time these arms came into use, painting of the white stripe was standard. Photographs, unfortunately, do not record the early distant signals, but they were probably much the same, showing a green light and perhaps having a green blade as well.

There seem never to have been distant arms on the same posts as home arms with these signals. When there was more than one track, bracket signals were used that look exactly like British bracket signals, but with a completely different interpretation. Each signal post referred to a different line, not to different routes. The post with the higher signals referred to the principal line, and lower signals to the subordinate line. Multiple arms on the same post referred to different routes, the top arm to the leftmost. At an interlocking, two arms often routed to the through route and to a facing crossover, the crossover arm apparently on top. It is definitely not clear from photographs when the top arm finally referred to the principal route. Photographs do show, however, that signals were maintained at Stop and cleared only to permit a train to pass, from the earliest times.

Arm C was specifically for manual block where permissive working was allowed. It was a three-position lower-quadrant signal, a rare thing. Lowered to 45° the aspect was Permissive-block, and lowered to 75° the aspect was Clear-block. Where permissive working was not allowed, the two-position Arm A was used instead. Many photographs show the 3-position signal for the freight lines, and the 2-position for the passenger lines.

Arms F and G were used with early US&S electropneumatic block. Although there are two lenses in the spectacles, they were not 3-position signals. This was an early example of the US&S "continuous light" spectacle, later familiar with three roundels. The distant arm is shown painted green, since there appears to be a color difference rendered in the black-and-white photos. The bad idea of green arms for distant signals was widely adopted in the United States. At H is shown a block signal for both directions, with two arms on the same post, and arranged for using only one lamp, here on the right. The green lens for this arm is above it, while the green lens for the other arm is below it, in the usual position.

Arms counterweighted to return automatically to horizontal could be cleared by pulling on a single wire, and this method was probably used for distant signals quite generally. Photographs show a wire extending past the camera for this purpose. However, positively restoring a signal to Stop was so important, especially in view of ice and snow, that a second wire was often used for this purpose. Most secure, however, was operation by 1" pipe, using bell cranks and other fittings. This was easily applicable to signals in the immediate neighborhood of the signal cabin, or at moderate distances from it. The PRR put these rods in neat timber trunking in the early days.

From the 1890's, the Pittsburgh, Fort Wayne, and Chicago, later the Northwestern Division, used a three-position lower-quadrant signal, probably the Eclipse patent signal. The three aspects were horizontal, 45( below horizontal, and 75( or more below horizontal. The Eclipse signal gave an absolutely vertical aspect for clear. Two arms were required on each home signal, the lower arm to govern diverging movements. If there were no diverging movements, the lower arm was fixed horizontal. One arm was used on a distant signal, or on a distant switch signal, to be horizontal when the switch was open. High semaphore arms were at least 25 ft above the rail, low (dwarf) semaphores no higher than 2-1/2 feet. The painting of the arms was not specified, except that it had to contrast with the background. The Fort Wayne later originated painting arms yellow with a black stripe. Advance home signals were to be used where necessary. Distant signals were to be at least 600 ft from the home signals of a block in the rear. These signals were developed by W. McC. Grafton, Signal Engineer of Lines West, and were used on the Southwestern Division as well. Grafton preferred white for clear, and favored illuminated semaphore blades for night use. Grafton could not persuade Lines East to accept his recommendations.

The PFtW&C is probably also responsible for the invention of the so-called crossing target once familiar in the Midwest, some time before 1875. This was a bar pivoted at the center to rotate in a horizontal plane, and placed at a crossing making equal angles with the two lines, so that it could be seen from both. By night, lamps were suspended from the ends of the bar. A horizontal bar gave right-of-way to one line, an inclined bar to the other. The signal was praised as never allowing trains on the two lines to receive simultaneous signals to proceed by error. This signal was the Midwestern equivalent of the New England ball signal, and was in service before semaphores of any kind. It nearly outlasted semaphores, as well.

Upper-quadrant, 3-position signals replaced lower-quadrant, 2-position signals after about 1910. Upper-quadrant signals were patented by the Baltimore and Ohio signal engineer F. P. J. Patenall and L. F. Loree of the Pennsylvania around the turn of the century. The first installation of upper-quadrant signals was on the 15 miles between Philadelphia and Elwyn, on 25 September 1906. The Pennsylvania Railroad adopted yellow for caution quite late (like the New York Central), retaining the white for clear and green for caution until after 1914, although by that date yellow for caution was found at a few points. The change was complete from 1919. On semaphore signals, the lens for the clear aspect was simply missing, so the signal light would show through directly. The other two lenses were red and green. As long as the illumination is by oil lamp, white and green aspects are brighter (respectively) than green and yellow, which is one reason, in addition to inertia, for their retention. With electric illumination, a bluish green and a bright amber can be used and, of course, are superior. The adoption of yellow for caution was made possible by the development of a suitable yellow glass by Corning, and a new green glass, so that the two aspects were less easy to confuse. Actually, green was adopted for clear before a suitable yellow was available, and for a few years, from about 1895 to 1910, caution was red and green shown side by side, but, of course, not on the Pennsylvania.

In the 1890's, while green was still used for the Permissive aspect of a manual-block signal, some way of distinguishing it from the green of a distant signal at Approach was desired. This was done by using a lamp that gave two green lights side by side, one directly from the lamp, and the other through a mirror, so that there would always be exactly two lights or none. This was an adaptation of the Carter caution lamp on the Chicago and North Western that showed red and green side by side.

There was an aspect not found elsewhere, the Caution aspect formed by two yellow distant signals in a vertical line (or an arm and a fixed light). Its indication was to reduce immediately to medium speed (usually 30 mph), approaching a facing switch or the next signal prepared to stop. Distant semaphores displayed only three aspects, Clear (green over yellow), Caution (yellow over yellow), and Approach-medium (yellow over green). The Approach aspect, yellow over red, has an indication very much like that of Caution, except that there is no reference to a facing switch. Both Caution and Approach aspects survived in position-light signals.

The Pennsylvania was probably the only road to use a home arm and two distant arms on the same mast to display Approach-medium with lower quadrant semaphores (green over yellow over green). This aspect can be seen displayed in a photograph on p. 41 of Ref. 6. Where this aspect was not needed, the lower arm was a fixed yellow light (for uniformity of aspect with other signals) in the district where they were used. This aspect was typically used approaching crossovers on four main tracks. The Pennsylvania introduced No. 15 crossovers at Paoli interlocking in 1896, which could be used at 30 mph. No. 20 crossovers, which should allow 45 mph, were also in use by 1914. The common No. 10 and 12 crossovers would restrict speed to 15 mph, as on most other railroads.

The adoption of the 3-position, upper-quadrant semaphore caused a thorough revision of signal aspects on the Pennsylvania, embodied in the Rudd-Rhea report of 18 August 1905. This influential but rather obscure report was the result of a meeting betweeen A. H. Rudd of Lines East and Frank Rhea of Lines West on 25 May 1905, with the aim of harmonizing practice systemwide. Elimination of separate distant arms made a much simpler display possible. Although most companies adopted a three-arm standard signal, with the arms referring to high-, medium- and slow-speed routes, the Pennsylvania decided that two arms of equal length were sufficient, and did not associate arms with routes at all, adopting pure speed signaling. Red over yellow in this system was Restricting. No need was felt for a Medium-approach aspect, for example, as the approach aspect already had medium speed built into it. Signals without two movable arms were to have a lower marker light showing the most restrictive aspect (that is, red or yellow). Interlocking signals had square-end blades, and the lights one over the other. Automatic block signals had pointed-end blades, and staggered the lights on either side of the post. Manual block signals were distinguished by round ends to the blades, and double red lights directly below, produced by a Carter reflector lamp. The recommendations of the Rudd-Rhea report were not immediately applied, but formed the basis of later practice. The lower marker lights can be seen in nearly every photograph of main-line semaphore signals, and Pennsylvania interlockings were different in having two-arm signals, not the three arms with the shorter lowest one used by other companies.

Dwarf semaphores displayed Slow-clear, Restricting, and Stop with their three aspects. Dwarf signals are used where they need not be seen at great distances, or would add confusion to main-line signals, and occasionally where there is not enough room for a high signal. The stop color on the Pennsylvania was purple, not red, so that it could not be seen at a distance, and would not be confused with the red lantern of a flagman, which would also appear at a low level. Pennsylvania yard switch lights and targets were originally white and green, then white and yellow after the adoption of yellow for caution. White meant the switch was set for the straight track, green or yellow for the turnout. Main-line switches had white and red targets and lights, usually elevated for visibility. Derails also probably had white and red lights. The Pennsylvania logically changed their markers from green and red to yellow and red when the signal colors changed after 1918. The green flags previously used as markers were replaced by red flags.

Position-Light Signals

Any account of Pennsylvania signaling cannot omit the characteristic position-light signal that is so strongly associated with it. These were first used in 14 February 1915 between OB (Overbrook) and Paoli, near Philadelphia, on 15.5 miles of quadruple track in connection with the suburban electrification. They were developed by Arthur Holley Rudd, the company's Signal Engineer (born 1867 in Connecticut, educated at Yale University, and joined the PRR in 1886. He went to the New York Central and Hudson River in 1892, then to the New Haven in 1894, and to the Lackawanna in 1900, returning to the PRR in 1902. Assistant Signal Engineer 1903, Signal Engineer 1907, System Chief Signal Engineer 1920, retired 1937). It is fortunate that A. H. Rudd was a foreign member of the Institution of Railway Signal Engineers of London (from 1910), and presented historical surveys of signaling on the Pennsylvania Railroad at meetings in London in May 1914 and June 1942. These surveys are a valuable source of first-hand information. His predecessor as signal engineer, C. C. Anthony, also left much technical information, in the Railroad Gazette and elsewhere.

The original signals had four white lights in a row (called 'tombstone' signals from the shape of the background). The lamps were on 18" centers, had 5.375" diameter lenses, and used 12V, 5W, 4 cp helical-filament tungsten lamps, supplied with 11 V by day, 6 V at twilight, and 3 V at night to conserve filament life. Five lights at 12" spacing had been tried first. Later, three light-yellow lights were substituted, after Mr. Rudd worked with Dr. William Churchill of the Corning Glass Company in the design of these signals. The light-yellow color is produced by the cover glass. A mirror is placed behind the lamp so that any light entering from outside cannot be reflected so as to make any light appear to be illuminated when it is not. Mr Rudd had noticed this defect in the original signals near sunset on the east-west line on which they were first used. Dr. Churchill developed the aspheric zone lens of 2.250" focal length that contributes to the efficiency of the signal. He also developed the signal yellow glass, and also the lunar white signal glass, used in other color-light signals. Lunar white was never used for the clear aspect as intended, but was found useful by other companies for the Restricting or Permissive aspects, or for dwarf-signal lights. The Figure shows the path of the main rays (a), a ray from outside reflected at the cover glass (b), and the path used to make the signal visible from close up (c). Note that there is no reflector directly behind the lamp, which would make the system more efficient, but also subject to phantom aspects. Rudd and Churchill were joint patentees, the first patent being issued on 14 March 1916, and licensed to all major signal contractors.

The large tombstone backgrounds behind the lights were used only on the Overbrook to Paoli initial installation, where they survived into the 1930's before being replaced by the 3-light signals with round backgrounds. The tombstone backgrounds were subject to considerable wind pressure that required sturdy and heavy supports. Backgrounds of reduced area closely following the light arrangements were introduced by 1918. With these, the lights projected through holes in the background. They were finally replaced by the perforated round backgrounds when rows of 3 lights were found sufficient, in 1921.

Rudd had been present at the tests of Dr. Herschel Koyl's illuminated semaphores in 1887. These were well-contrived, but failed because at a distance, as Rudd said, "They looked like the full moon," and their aspect could not be determined. This must have been in his mind as he worked on the position-light signals, and he was relieved when he discovered that these signals could be read when sighted, even at great distances. The line on which they were tested ran almost due west, and the evening sun made ghost aspects in each lamp of the first signals. With the help of Dr. Churchill, this difficulty was thoroughly overcome. Any light entering a lamp from outside cannot find its way out again. For reasons of economy, as few lamps as possible should be used. It was found that three lamps in a row were as good as four.

The position-light signal has every advantage that could be desired: It gives the same aspects by day and night; it does not depend on color; its aspects are visible at great distances, and are more evident in fog and bad atmospheric conditions than those of any other kind of signal; it requires very little power, because of the efficiency of its optical system; it has no mechanical parts; and, finally, the failure of one lamp does not destroy an aspect. The electrical economy of the signal is such that it can be operated from primary batteries, taking as little power as any kind of signal, since it can be approach lighted. Although developed on an electrified line where power was easily available, it was also designed for use on lines without electric power. It requires only 15W to display a single arm, which is less than a color-light signal, where additional power is necessary to compensate for absorption in the color glass. Stop can be displayed with 15W, instead of with the three red lights of a normal color-light interlocking signal. It is very difficult to understand why it was not generally adopted, since it has no defects.

Curiously, some position-light home interlocking signals were equipped after 1955 with two red lenses to show the Stop aspect, the pivot light being extinguished. The first trial was at Overbrook on 25 September 1954. If this was done merely by installing red lenses, as it seems to have been, the result is a dimmer, less-distinct signal than the original row of three lights. Under bad conditions, it must become downright hard to see. I have been unable to find the reasoning behind this modification, but Waytel reports that it was ordered by a high official. I thought first that it was some ignorant regulatory influence, but it seems to be a result of the ignorant management by lawyers and accountants that took over about this time. At any rate, it is totally unnecessary and can offer no benefit whatsover.

Position-light dwarf signals had four white lights, 4" diameter, with frosted cover glasses to limit their range so they would not be confused with high signals. Later, lunar white lenses were used. They displayed only the Stop, Restricting, Slow-approach, and Slow-clear aspects, using one pivot light and three positions lights two at a time. Curiously, these signals have been adopted world-wide as subsidiary signals. Initially, the signals had the usual configuration of the vertical lights at the left, but the housing was inverted around 1930 to put them at the right to provide better clearance for small track spacings.

Position-light signals were used strictly as speed-signaling, not route signaling, so arms do not correspond with routes, as they do on most roads (even though, technically, this is usually called speed signaling as well). An "arm" of a position-light signal is one assembly of up to nine lights, with or without a black circular target to furnish a background. The target is 54" in diameter, the lights are 18" apart, and the lenses are 4.5" in diameter. The arm is 24 ft high above the rail. A marker light or second arm is 17 ft high. The aspects from the 1941 Rule Book are shown below.

While the use of these aspects will be generally understood, some explanatory comments might be in order. Manual block aspects are Clear-block, Permissive-block and Stop. The marker light is necessary to distinguish the block signal from other clear signals that may be received near an interlocking. Approach-medium and Medium-clear are used at main line crossovers and junctions, where the turnouts can be used at higher speeds than the usual 15 mph, in order to avoid slowing trains unnecessarily. There is a background around the lower arm in this case, since it is viewed at speed. Medium speed was usually 30 mph, but if a permanent yellow triangle outlined in black was also displayed, medium speed for that signal was 45 mph. The lights used to display the Slow-approach and Restricting aspects are not provided with a background, since they are approached only at low speed.

The Stop-and-proceed aspect was used with automatic block signals. A permanent yellow disk showing the letter 'G' in black permitted heavy freight trains (more than 90 cars or more than 80% of the engine's tonnage rating) to pass a stop-and-proceed signal, without actually stopping, at restricted speed. Before roller bearings were common, starting a heavy train was much more difficult than keeping it rolling at a low speed.

Caution was used as a distant signal to protect isolated switches within a block, and for similar uses. The indication was to approach the next signal, or any facing switches, prepared to stop.

One of the principles of position-light signals was the elimination of as many extraneous stop aspects as possible, an excellent principle that reduces the chances of misunderstanding as well as expense. No position-light aspect requires more than two arms, and the lower arm is usually only partial, or just a single marker light. This contrasts very favorably with the usual display of a swarm of red lights in common American signaling practice.

Position-light signals replaced other signals steadily but slowly, first on the chief main lines, and then on the less important ones. By 1 January 1935, 71.5% of block signals were position lights, and 82.3% a year later. Horseshoe Curve still had semaphores in 1938. Semaphore signals were still to be seen as late as the 1950's, however, in many locations on secondary lines. The Pennsylvania did not usually rush to replace equipment that was in good order.

The signals outside a Pennsylvania Railroad station were block signals, not the familiar semaphore train-order signals seen everywhere else in the country. The train-order signal was a yellow flag or yellow lamp, or later, an illuminated flashing 'O' on the mast of a position-light signal. The train was stopped or slowed with the block signal for orders when necessary.

An important principle observed in Pennsylvania signaling was the "caution principle" that a caution indication should always be accompanied by an immediate physical action, usually a reduction to medium speed. This develops a safe habit of doing something when the signal is observed, to fix it in the memory. Where a distant signal indicates merely "proceed prepared to stop at the next signal" it is too easy to pass it without taking any action, and then forget it.

Cab Signals

The final remarkable contribution of the Pennsylvania to railroad technology was the cab signal, a representation in the engineman's cab of the state of the block in which he was moving. The complete story is quite interesting, but space demands that we can give only an outline here. The Interstate Commerce Commission report for 1903 urged general adoption of the block system. Accident reports had been required only since 1901, and previously the efforts of the ICC in safety had been directed towards grab irons and couplers, not operations. A bill was introduced in Congress in 1903 to empower the ICC to compel adoption of the block system, but it did not pass. A second attempt in 1906 succeeded in passing a bill that directed the ICC to investigate block signals and automatic train control, and to report. The report appeared in 1907, and a board of engineers and railroad officials was established, which submitted annual reports. This was an excellent board, and would have fostered a spirit of cooperation between the ICC and the companies while leading to effective results. Unfortunately, but precisely in line with the nature of American politics, the ICC Bureau of Safety, composed entirely of bureaucrats and enthusiasts, caused the board to be dissolved in 1912 as it assumed its responsibilities. Thus began the history of bitter confrontation and ineptitude that marked ICC efforts in safety thereafter.

A competition for means of providing automatic train control, which meant stopping a train automatically that had passed a stop signal, was then opened, and inventors thronged to Washington with their schemes. There had been inventions along this line for many years, but the only one that was practical was the automatic trip system used on rapid transit lines, which was already in service. In 1880, Axel Vogt, later Master Mechanic of the PRR at Altoona, and Joseph Wood had invented and patented an automatic train stop based on a trip lever at cab roof level, but it did not see service. Most of the schemes presented to the ICC were completely unworkable and impractical, a number of them feasible but impractical, and a very few that would actually function in the way intended. Some of these were actually tested, but the only ones that found actual use were the Miller system on the Chicago and Eastern Illinois, and the Regan sytem on the Chicago, Rock Island and Pacific.

The ICC, thwarted in its effort to compel the block system, acquired the power to compel train control in the Transportation Act of 1920. It did this soon afterwards, arbitrarily selecting divisions on a number of lines (some without more than one or two passenger trains) without consultation or reason, in a vindictive and confrontational spirit. Something had to be done to get a reliable system with which to implement the order, so the General Railway Signal Company developed an inductive intermittent system that was economical and reliable. Most companies compelled to adopt train control used the GRS system. The Pennsylvania, which was well-known as having the block system on all passenger lines, was not affected by the order.

The Pennsylvania and the Union Switch and Signal Company, who had cooperated so many times before in signaling matters, looked for a better solution. Their fundamental idea was an alternating-current signal in the track circuit that could be picked up by receivers on the locomotive. If the signal was present, then the block was unoccupied, and the brakes were held off. In the absence of the signal, a relay dropped and applied the brakes. This was to be a continuous inductive train stop, with advantages over the intermittent variety.

Tests were carried out in central Pennsylvania, on a line where heavy traffic would not interfere (Tyrone to Lock Haven). A. H. Rudd was very interested in these developments, and was on the spot. Either as a test measure, or on Rudd's suggestion, the apparatus was fitted with lights to show whether a signal was being received or not. Rudd noticed that the lights were a true cab signal, that reflected the state of the block ahead at all times. The emphasis now changed from a train stop system, which Rudd disliked, to a cab signal system, which he greeted with enthusiasm. Cab signals of various kinds had been invented before, but here was a practical, reliable system that was economical as well. It represented one of the first industrial uses of the new triode vacuum tube in control circuits.

The simple two-speed system (H and L states) was soon replaced by a three-speed system by the use of coded track circuits. Eventually, a four-speed system could show Restricting, Approach, Approach Medium, and Clear by using three different codes (Restricting was no code, block occupied).

Rudd made a deal with the ICC that if they would not require the Pennsylvania to include train stop, then the Pennsylvania would use cab signals on all lines with automatic block, which would be the majority, and include all the lines of heaviest traffic. The unique deal was accepted, leading to an intimate association of cab signals with the PRR. In the Rule Book, it is evidenced by Rule 515:

515. The movement of trains not equipped with cab signal apparatus, including whistle and acknowledger, in operative condition for the movement, is prohibited except as provided on the time-table or in emergency when authorized by the superintendent, and then as prescribed by Rule 516.

Rule 516 required movement at not to exceed medium speed, or authorization by Cab Signal Clearance Card CS to proceed at normal speed when special steps were taken to ensure a clear block. After World War II, however, this agreement fell by the wayside, and brake actuators were added to the cab signal apparatus. Unlike some roads that adopted cab signals, the Pennsylvania did not eliminate lineside signals, except perhaps in a small number of locations.

Another innovation that proved very useful in the movement of trains was inductive train radio. This system used the lineside wires to conduct the signals, which were transmitted at frequencies lower than those used in space radio. Connection between the lineside wires and locomotives or cabin cars was made by induction (not radiation) from the antennas that looked like handrails on the roofs of the vehicles. Communication between the front and rear of a train was very useful, in things like brake tests and flagging. The system was tried out on the Belvidere-Delaware line north of Trenton in 1942, and then was extended over the main line. This was done before the era of VHF and UHF radio, and was also unique to the Pennsylvania.

The Indianapolis Division

The Indianapolis Division consisted of: a main line from Logansport, Indiana through Indianapolis to Louisville, Kentucky, about 197 miles long; the Vincennes Branch down the White River from Indianapolis to Vincennes, serving the coal mines in the area, about 115 miles; the secondary track from Columbus, Indiana to Madison, on the Ohio River, about 45 miles; the lightly-used secondary track from Columbus northeastward to Dublin Junction (Cambridge City), Indiana on the Columbus Division, 56 miles; and the short New Albany Branch, 5 miles. Counting all lines, there were about 310 miles of main track and 145 miles of secondary track, for a total of about 455 miles. The accompanying divisional diagram, which appears below, shows the block stations and distances between stations for all lines. Train directions on the Pennsylvania were Westbound and Eastbound. On the Indianapolis Division, Logansport to Louisville was Eastbound, which worked out properly in the Indianapolis area. On the Vincennes Branch, Kirk to Kraft (toward Indianapolis) was Eastbound. All train order stations were block stations, except for the offices at the passenger stations at Indianapolis and Louisville, whose telegraphic addresses were UN and D, respectively.

The division included a line of great historical interest, the Madison and Indianapolis Railroad. The Madison and Indianapolis was the first steam railroad in Indiana, whose inaugural journey was in 1838. On 4 July 1834, a horse car was run over the 1-1/4 miles of the Lawrenceburg and Indianapolis on some description of railway, but this was only a curiosity, and nothing further came of it. The Madison and Indianapolis was the only railroad actually constructed in the pioneer program of internal improvements of the State of Indiana, signed by the governor on 27 January 1836, that included canals and turnpikes as well as the railway. The expense of this plan was said to be one-sixth of the wealth of the entire state, and corruption was rife in the disposal of the bonds. The line is notable for the 1-1/3 mile inclined plane from Madison to North Madison, rising 413 ft. This inclined plane was built between 1836 and 1841, first worked by teams of eight horses, and then, between 1848 and 1868 by an 0-8-0 with a separate cog engine driving a pinion that engaged the central rack. In 1868, the Baldwin 0-10-0 Reuben Wells began adhesion working. Reuben Wells was an early master mechanic of the M&I, and designed the earlier cog engine as an adaptation of a standard Baldwin flexible 0-8-0 of the time.

The line was built northward from North Madison. In the first step, 28 miles of line was built, and 25 miles more were graded. The method of construction reported is unusual. English iron flat-bottom rails weighing 45 lb per yard, delivered in 15 ft, 15 ft 9 in, and 18 ft lengths were spiked to cedar ties (later oak) trenailed to 10 in x 10 in oak sills with locust pins. One would have expected flat-bar rail to have been spiked to the oak sills, which was the normal mode of railway construction in the West at the time and later. The first steam engine was lost at sea on its way to New Orleans, so another engine was borrowed from the Louisville and Portland Canal Company, which had apparently obtained a second-hand engine from the Lexington and Ohio (which only got as far as Frankfort) in anticipation of operating its own short line around the falls. This engine was used for an excursion over the completed part of the line in November 1838, and was then returned. Horses were used until steam locomotives arrived. The formal opening was on 1 April 1839. In 1843 the railroad was sold by the state to the Madison and Indiana R. R. Co. in a traditionally corrupt transaction. In 1847 the line was complete to Indianapolis, where it had no physical connection with other railroads until after the Civil War, though the Indianapolis stations were adjacent. The lack of connection was probably encouraged by the city to ensure a profitable transfer operation, but seriously hampered important troop movements in the Civil War, causing later movements to be made through Cincinnati instead.

The Jeffersonville and Indianapolis Railroad Company completed the 67-mile line from Jeffersonville to Columbus in 1852. Its line actually extended 10 miles farther north parallel to the Madison and Indianapolis, as far as Edinburg. This segment was built as a threat when a satisfactory traffic agreement was not initially forthcoming from the M. & I. The railroad was projected as early as 1832, but nothing happened until 1849. The Madison and Indianapolis and the Jeffersonville and Indianapolis were consolidated into the Jefferson, Madison and Indianapolis R. R. Co. in 1866. The Jeffersonville and Indianapolis controlled the Kentucky and Indiana Bridge Company, which owned the bridge over the Ohio between Jeffersonville and Louisville. This bridge, owned jointly with the Louisville and Nashville, was opened 1 March 1870 as the Fourteenth Street Bridge. Albert Fink, a famous bridge engineer, who was a leading figure in the L. & N., was the designer. A new riveted truss steel span double track bridge replaced the original bridge in 1920. This bridge is about a mile long, and includes a 643 ft 10-1/2 in span, one of the longest in existence. These lines came under the control of the Pittsburgh, Cincinnati, Chicago, and St. Louis with the majority of the other lines making up the Indianapolis Division in 1890, although locomotives were still lettered for the J. M. & I. R. R. as late as 1893.

The original J. M. & I. Louisville station was at 14th Street and Main, beside the Ohio and Mississippi (Baltimore and Ohio) station, at the south end of the bridge. There was a break of gauge here between the J. M. & I. standard gauge, the O. & M. 6 ft gauge, and the L. & N. 5 ft gauge. The O. & M. line probably had three rails to accommodate standard gauge trains of the predecessor of the Big Four as well as its own broad gauge trains. The Louisville, New Albany and Chicago, later the Monon, also used the bridge for entry into Louisville. The main station of the L. & N. was at 9th and Broadway, very near the location of the later Union Station. A map of Louisville railways in 1950 is shown below, with Pennsylvania lines in red.

The Baltimore and Ohio and the Big Four later used the bridge of the Louisville and Jeffersonville Bridge and Railroad Company upriver, and the Monon and Southern the Kentucky and Indiana Terminal bridge at New Albany downriver. The so-called River Line, originally proposed for the L. & N. connection to Cincinnati in the 1870's, was resurrected for the B & O, C. & O., Big Four, and I. C. trains, and Central Station was built on it. Close to the river, this line was subject to flooding.

The lines between Indianapolis, Louisville, Madison, and Dublin Jct (Cambridge City), with the short New Albany branch, 226 miles in all, comprised the Jeffersonville, Madison and Indianapolis RR. The Vincennes Branch was built by the Indianapolis and Vincennes RR in 1867-69, as part of a through line to Cairo, Illinois, Fulton, Kentucky, and beyond that never came to fruition. The continuation beyond the Wabash was the Cairo and Vincennes RR, which later became part of the New York Central. Together with the line from Frankfort to Logansport, built by the Terre Haute and Logansport, the Vincennes Branch was part of the Vandalia Line, and always operated as part of the Pennsylvania System. The line from Davis to Frankfort was built in 1918 as a shortcut for Southern Indiana coal, and also permitted direct Louisville - Chicago passenger service. The new line replaced trackage rights over the Lake Erie and Western (later Nickel Plate) from Indianapolis to Kokomo.

The Pittsburgh, Cincinnati and St. Louis Railway, formed in 1868 by the consolidation of the Pan Handle Railway Company, the Steubenville Bridge, and the Steubenville and Indiana Railroad, controlled the Chicago and Indiana Central Railway, which together with the St. Louis, Vandalia, Terre Haute, and Indianapolis Railway (the Vandalia) owned the east-west lines at Indianapolis. The Pennsylvania System originally controlled the other St. Louis line, the Indianapolis and St. Louis RR, which was later sold to the Big Four (CCC&St.L - New York Central System). In 1890, the P. C. & St. L, J. M. & I, Chicago, St. Louis and Pittsburgh, and Cincinnati and Richmond were consolidated into the Pittsburgh, Cincinnati, Chicago and St. Louis Railway. In 1916, the P. C. C. & St. L. was consolidated with the Vandalia and several other companies to form the Pittsburgh, Cincinnati, Chicago and St. Louis Railroad Company. The P. C. & St. L. and the P. C. C. & St. L. were both popularly known as the Panhandle, preserving the name of an original component, named after the narrow peninsula of West Virginia that it crossed.

The Pennsylvania System was reorganized in 1920 into the Eastern, Central, Northwestern, and Southwestern Regions, and no longer were operations divided at Pittsburgh and Erie. The Indianapolis Division fell into the Southwestern Region, which was essentially the P. C. C. & St. L., headquartered in St. Louis. In 1925 the two western regions were consolidated into the Western Region, with headquarters at Chicago, and the Indianapolis Division became part of the Southwestern (Grand) Division. Keeping track of corporate relations in the Pennsylvania System is a difficult task, since more than 600 companies were involved, and the relations between them of stock control, lease, and so forth, were constantly changing.

The original line main line ran through the center of Jeffersonville on an inconvenient route with sharp curves, a relic of the original layout when there was but one Ohio River bridge. This was replaced by a straight alignment on the western side of town, probably when the Ohio River bridge was replaced in 1920, while the original line was retained for access to shippers with sidings along it, and for interchange with the B. & O. and Big Four.

Passenger service on the main line in 1950 consisted of three Louisville-Chicago trains, one Louisville-Indianapolis train, and their companions in the reverse direction, in addition to the every-third-day South Wind from Chicago to Louisville and beyond, which had been introduced in 1941. The local from Indianapolis to Vincennes, and the gas-electric cars from Columbus to North Madison had disappeared some years earlier, as well as the Terre Haute - South Bend train that used the division north of Frankfort. The Madison Branch had been reduced to secondary track when passenger service over it was abandoned, but at the rather high speed limit of 30 mph. K4's were the usual power on the passenger trains at this time, but diesels were probably already used on the South Wind. At this time, the every-third-day South Wind, introduced in December 1940, covered Louisville-Indianapolis in 2 hours even, an average of 56 mph. The 1964 every-other-day South Wind took 22 minutes longer, averaging only 47 mph. Stops had been added at Seymour and Columbus, but even in 1950 No 327 required only 2 hours 20 minutes, with four stops. In 1931, the fastest train took about 2 hours and 40 minutes, and the service was about as dense as in 1950. By 1963, the service had been reduced to two trains in each direction. The speed limits were generally 70 mph passenger, 50 mph freight on the Main Line.

Clagg interlocking at the Ohio River movable span bridge between Louisville and Jeffersonville was the key PRR location in the Louisville area. Its interlocking limits spanned the river, since on the north side it controlled the secondary track to Ade in New Albany, 4 miles to the west, and on the south side the junction with the IC double track from Central Station. Trains were operated by signal indication on single track between Clagg and Boyd (Rules 261-264). The secondary track to Ade may have been the original Louisville, New Albany and Chicago route, and was used by the J. M. & I. for commuters from Louisville to New Albany.

At Louisville, the L&N station at 10th and Broadway, with its high, dark trainshed, also served the PRR and the Monon (Chicago, Indianapolis and Louisville). The switches at this station were operated by switchtenders in the old way, not by interlocking. Illinois Central trains, two each way per day, which used Central Station at 7th and Main Street, ran over the Pennsylvania from the Clagg interlocking at the Ohio River near Main Street southward on double track to Broadway not far from the L&N station, then diverged to IC Junction at Kentucky Street, where they joined their own line near the IC's Oak Street yard. The IC called these two points Main Street and Kentucky Street in the timetable. Southward trains on the IC were eastward on the PRR, and northward, westward. The night trains, 103 and 104, The Irving S. Cobb, were numbers 732 and 703, respectively, on the PRR. The day trains, 101 and 102, The Kentucky Cardinal, were numbers 712 and 733. The IC line was originally the Chesapeake and Ohio Southwestern, built by C. P. Huntington as part of a transcontinental scheme, and acquired by the IC in 1896. It ran from Louisville to Paducah, Fulton, and Memphis.

The Southern's St. Louis trains, Nos. 23 and 24, stopped at the Southern station at Fourth Street, where the L & N was crossed. Southern trains ran over 0.7 mi of the PRR from State Street, New Albany, to 10th Street, called the New Albany Branch. 10th Street, New Albany, was the block station Ade, which controlled the block-limit station State at State Street. At Ade, they entered the K&IT, crossed its Ohio River bridge, also used by the Monon, and passed the large yard at Youngtown (Louisville). From here it was 4.0 mi to LS Jct, where Southern tracks began, and 1.3 mi farther to Fourth Street, the passenger station. Eastbound train 23 was PRR 783, and westbound train 24 was PRR 762. Both trains had stops at State, no doubt to communicate with the signalman at Ade about the block. This stop could well have been part of the New Albany station stop, since State and the New Albany station are given as only a few hundred feet apart in the timetables. Between New Albany and Duncan, Indiana, the electric train staff was used on this difficult section by the Southern, a rare practice in the United States. The line south of the Ohio was originally the Louisville Southern, an original part of the Southern Railway in 1894, and north of the Ohio, the Lousville, Evansville and St. Louis Consolidated RR, acquired in 1901. The Louisville Southern connected with the Queen and Crescent route from Cincinnati to New Orleans, the Southern's western main stem, at Lexington and Danville.

The following Figure is a diagram of the Indianapolis Division

There were noninterlocked crossings with the Milwaukee at Seymour, and the Big Four at Franklin on the main line. These crossings had gates and co-moving targets. When the gate was clear, and the target was diagonal, trains could approach the crossing at 10 mph, and did not have to stop. Camp Atterbury north of Columbus was served by a secondary track with block-limit stations War and Camp, typical PRR names, controlled by Atterbury block station. Columbus is the most important point between Louisville and Indianapolis. There were yard limits, and secondary tracks diverging to Dublin Junction and Madison. The block-limit stations at Elvin, Brook, and Garden on the main line must have been quite useful when things were busy. Freight trains could be held at them, or sent out to them to wait, to reduce delays and clear tracks.

At Indianapolis, trains used Indianapolis Union Terminal and its associated joint railway. The stretch of east-west double and triple track through Indianapolis connected the Columbus and St. Louis Divisions, both busier than the Indianapolis Division. Double-track secondary lines to Kitley Avenue and Van Junction served freight trains. The Louisville line diverged not far east of Union Station, running parallel to U. S. Highway 31 to Louisville.

At Frankfort, north of Indianapolis, the Crawfordsville Branch from Terre Haute joined the Indianapolis Division from the southwest. The block station is called Frank, and its outlying block-limit station is called Fort. The Pennsylvania usually shortened town names, or chose completely different names, to get short, distinctive names that would not be confused on train orders. The Logansport Division was met at Van, on the south side of Logansport.

The 115-mile-long Vincennes Branch was a main track, but it was operated with only one open block station at Switz City! All the other block stations are block-limit stations, controlled either by Kraft in Indianapolis, or Switz City. The Switz City interlocking governs the IC crossing. The other four interlockings on the branch are automatic interlockings controlling grade crossings by the Monon, Milwaukee, Shasta RR, and C&EI. There are also non-interlocked crossings with the Big Four west of Minich, and with the B&O in Vincennes, as well as crossings with the Monon and the Milwaukee on the Linton Summit track. This line was worked by I1's, trains originating and terminating in the Bicknell yard. The principal traffic was coal, mined locally underground. Local freight service went 12 miles further into Vincennes, to connections with the C&EI, NYC, and B&O. The freight speed limit was 35 mph.

On the Indianapolis Division, we see five different adaptations of the block system for controlling trains. First, there is the main line with enough continuously open block stations to operate a busy line, on which there are both passenger and freight trains. Second, there is the Vincennes Branch, with a significant heavy freight traffic, in which block-limit stations protect train movements at the cost of a little extra time, while flexibility is retained. Third, in the Columbus-Madison secondary track, we also find block-limit stations, which could control a moderate traffic. Fourth, the Columbus-Dublin Jct secondary track has no block stations at all. It is a light-traffic line on which there would normally be only one train. Finally, there is even 15 miles of double-track main line controlled by frequent block stations across Indianapolis. The Indianapolis Division gives good examples of how the Pennsylvania operated trains on all kinds of lines. On multiple tracks, the tracks were numbered from the south to north (0,1,2 or 1,2, or A,B), and the timetable gave the usage and current of traffic on each. The A and B designations were used on secondary tracks.

All of this is gone today, leaving little trace, except for the bare Indianapolis - Louisville line itself, run by a short line delivering a few loads of scrap or gravel in trains that creep along the weedy track, and a bit of the Madison, run by the Port of Madison. Even the Columbus and St. Louis divisions are gone, replaced by alternate routings. Reference 5 tells of the ultimate decline.

References and Notes

Note: this list is incomplete, and will be expanded when time is available.

  1. H. W. Schotter, The Growth and Development of the Pennsylvania Railroad Company (Philadelphia: The Pennsylvania Railroad Company, 1927). An authorized business history taken largely from the annual reports.
  2. G. H. Burgess and M. C. Kennedy, Centennial History of The Pennsylvania Railroad Company, 1846-1946 (Philadelphia: The Pennsylvania Railroad Company, 1949). The last and most comprehensive authorized business history with background information and appendixes on locomotives and rolling stock.
  3. ______, Seventy Years of America's Greatest Railroad, The Pennsylvania, 1846-1916 (New York: Strong, Sturgis and Company, 1916), a brief description encouraging investment in the company, written by a brokerage house at the time of the peak of the company's fortunes.
  4. E. P. Alexander, The Pennsylvania Railroad, A Pictorial History (New York: Bonanza Books, 1967)
  5. E. P. Alexander, On The Main Line (New York: C. N. Potter, 1971). Excellent photographs of signal cabins (towers)
  6. E. Waytel, The First Position Light Signals and Subsequent Developments, The Keystone, Vol. XIV, No. 4, December 1981.
  7. W. J. Watt, The Pennsylvania Railroad in Indiana (Bloomington: Indiana University Press, 1999)
  8. F. Westing, Pennsy Steam and Semaphores (Seattle, WA: Superior Publ. Co., 1974). No photographs on the Indianapolis Division, but shows semaphores and trains up to about 1925.
  9. D. Ball, Jr., The Pennsylvania Railroad, 1940s-1950s (Chester, VT: Elm Tree Books, 1986). On pages 162-175 are photographs taken on the Indianapolis Division a few years later than the time considered here. p. 162 shows white/red switch targets; p. 165 has a scene at Davis; p. 167 and elsewhere a curious reference to the 'Louisville Branch,' which appears nowhere in the timetable; p. 168 has a good picture of Kraft, but no signals are shown; pp. 170 and 172 show IU Rly Interlocking - the dwarf signals are not PRR, of course; p. 173 shows white/yellow switch targets; p.175, although not on the Indianapolis Division, shows position-light signals with red lights for stop. pp. 116 and 84 show semaphore manual block signals with the double red marker lights; the blades are yellow with a curved black stripe. p. 67 shows a distant semaphore with marker light. p. 64 is a good view of a position-light signal. Note the unlighted marker light. p. 47 shows a (rare) signal with a lower arm that has a full round background.
  10. Details of the Bristol, Pa. accident of 1865 are from C. F. Adams, Railway Accidents, p.p. 150f.
  11. Transactions of the Am. Soc. Civ. Eng., 4 (May 1875) and Engineering News, 9 (11 February 1882), p.45. Reprints of Mr. Welch's report on railroad safety signals and the block system made on 17 October 1866 in New York City.
  12. Railroad Gazette, 22 (June 20, 1890) pp 438-439. "Block Signaling In America," including a report on a paper by Robert Stewart.
  13. Signal Section, Association of American Railroads, American Railway Signaling Principles And Practices (Chicago: AAR, 1953), Chapter I, History and Development of Railway Signaling. On p. 15, the author refers to the 1866 report by Mr. Welch, but obviously never read it, or the erroneous remarks he makes would not have been made. He is relying mainly on reports of the report made by Mr. Stewart in 1890 in the Railroad Gazette. The drawing on p. 16 is purely invention. The form of the signal shown is taken from later PRR practice, it must be assumed. The account of the first interlocking is accurate, but the illustration on p. 33 labeled "First S&F interlocking in America (1875)" is unaccountably of the East Newark plant, not the Top of Hill plant of 1870. This work contains other examples of the same kind of uncritical history. On p. 68 is a drawing claiming to show the first automatic semaphore block signal operated and controlled by electricity, 1893. The drawing shows two kinds of counterweighting, one impossibly connected, no signal lamp brackets, two arms on a signal out in apparently plain track, and what appear to be pneumatic cylinders, but are probably intended as solenoids. The signal resembles an early US&S electropneumatic semaphore (although these were in use in 1883, long before 1893). That is, the drawing was invented and does not represent an actual example. The line drawings in this work must all be discounted as unreliable, but the photographs are of value. Unless, of course, they are captioned as on p. 70. This is definitely not one of the first position-light signals, although it appears to be in the correct area, near Wynnewood, Pa., judging from the number plate.
  14. Robert B. Shaw, Down Brakes (London: P. R. Macmillan, 1961). "A history of railway accidents, safety precautions, and operating practices in the United States."
  15. C. C. Anthony, The Railroad Gazette (August 16, 1895) p.549, "Principles of Block Working."
  16. William Robinson, History of Automatic Electric and Electrically Controlled Fluid Pressure Signal Systems for Railroads (Brooklyn, N.Y.: William Robinson, 672 Putnam Ave., 1906). His account of how his ideas and patents were used by others without proper credit.
  17. See The Standard Code of the American Railway Association, 9th ed., November 1897, which has the original and modified rules, and the edition of October, 1953 to see the changes that have been made since then.
  18. James O. Fagan, (Boston: Houghton-Mifflin, 1908).
  19. The Pennsylvania Railroad, Book of Rules, edition of 1 September 1857.
  20. The Pennsylvania Railroad, Book of Rules, edition of 1 November 1874.
  21. The Pennsylvania Railroad, Book of Rules, edition of 1 September 1882.
  22. The Pennsylvania Railroad, Book of Rules, Lines West, edition of 1 February 1896.
  23. The Pennsylvania Railroad, Book of Rules, edition of 28 September 1949.
  24. O. S. Nock, Fifty Years of Railway Signalling (Newton Abbot: Ian Allan Ltd, 1962). A history of the Institution of Railway Signalling Engineers, containing references to A. H. Rudd.
  25. The Pennsylvania Railroad, Time-Table No. 13, Indianapolis Division, dated September 25, 1949.
  26. "The Madison and Indianapolis Railway," Indiana Magazine of History, XII (1916) pp 236-238. There are some inconsistencies and misinterpretations in the early technical history, but this is the usual source for most historians.
  27. Buley, The Old Northwest (Indiana Historical Society, 1950), p. 313.
  28. Official Guide Of The Railways, August 1931 and October 1963.
  29. Illinois Central Railroad, Time Table No. 26, Kentucky Division, dated December 4, 1949.
  30. Southern Railway System, Time Table No. 79, St. Louis and Louisville Divisions, dated January 29, 1950.
  31. B. B. Adams, The Block System of Signaling on American Railroads (New York: The Railroad Gazette, 1901).


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Composed by J. B. Calvert
Created 10 October 2000
Last revised 27 December 2008