Ball signals were derived from tide signals, and were the earliest fixed
signals used in the US. They were used at crossings, drawbridges,
junctions, and as station signals, and were found principally in New
England, but some existed as far south as Maryland and as far West as
western New York State. The simple example shown here is said to have
been the last ball signal in service. It was located
at the B&M - MEC crossing in Whitefield, NH.
These signals were at the east end of the siding at Wagon Mound, NM. The
block behind us is occupied, so the signal in the distance is showing
Approach for the leaving signals at the other end, which are at stop in this
APB territory. Both of the leaving signals here are at Clear, which might
seem curious. Actually, the switch is a spring switch, so a train could
proceed on either the main or the siding. Note that the main track blade
has square corners, and the siding blade has rounded corners. Shortly
after this picture was taken, the block in advance was occupied and the
main track signal went to stop. Curiously, the siding signal remained at
Clear, so the three signals displayed three different aspects. The siding
switches were not electrically locked, so could be thrown in the face of
an oncoming train.
This signal gave two aspects, depending on the aspect of the
home signal ahead, vertical and inclined. It was located east of Casper
near the North Platte bridge, governing entrance to the ABS section
through this area, and removed when the passenger trains were
discontinued. Note the moon.
This Denver & Rio Grande train order signal was at South Denver
tower, the northern end of the Joint Line. A train order delivery post is
also shown; it can handle four forks, one more than usual, since this was
the beginning of a helper district to Palmer Lake. The light on the
shows that the train order to be delivered allows the train to advance
past the station, a DRGW peculiarity. Orders could then be delivered with
the train in motion past the signal. The signal is two-position,
lower-quadrant, and the two arms share one lamp (which can be seen). A
dwarf searchlight signal, for reverse movements, can also be seen.
This Northern Pacific interlocking signal near Minneapolis is the
standard 3-arm upper-quadrant type. Note the painting and the lengths of
the arms. The upper and lower arms are fixed at horizontal, and only
display a red light. The middle arm has a motor, and can display three
aspects. The signal as a whole displays the Stop, Medium-Approach, and
Medium-Clear aspects. There is a switch in advance of the signal. The
lamps are electric. The signal post is painted black; it is a mystery why
this indistinct color was so often chosen.
This signal with home and distant arms was typical of the US&S Type B
signals used on the Southern Pacific between Tucumcari and El Paso.
These Union Switch and Signal Type B semaphores were excellent, and saw
long service. The mechanisms were easy to maintain, since they were in
the signal bases, and were very rugged and reliable. The arms have
continuous-light spectacles, and are painted in the standard manner.
Extra 7134 East at Oscuro, NM in June 1991.
This signal pair stood on the Southern Pacific a mile south of Carrizozo, NMex. some years ago. There is a siding switch in advance of the two-arm signal. When a train is waiting at the siding, the signal shows stop, both arms horizontal. When the switch is opened, the light just below the number plate goes yellow, and the train can proceed onto the siding. Or at least that is what I have heard. The whole story of these little lights beneath the number plate is now under discussion, and anyone with illumination is invited to participate. I never saw one lighted. Flashing yellow lights were sometimes added to similar signals to show Approach-Medium, but these would have been above the number plate and of a larger size. This was not CTC territory when the picture was taken, and there were no Approach-Medium aspects in the area. If a train is approaching the siding at the far end, the home (upper) arm is lowered, but the distant (lower) arm is horizontal, the Approach aspect. A train holding the main track can proceed to the other end of the siding. The one-arm signal at the left is the starting signal for the next block. Since this is Absolute-Permissive Block territory, it goes to Stop as soon as a train passes the next siding in advance. The triangular plate whose back we see indicates that the signal is controlled by conditions in addition to track occupancy, such as a high-water alarm (probably the case here) or a slide fence.
The lower quadrant arms have been replaced by upper quadrant arms on this intermediate signal near Pastura. The signal shows only two aspects. A few signals in this vicinity were modified in this way. Note the little light on the signal at the left.
Signal is displaying Approach. The lower arm is used for displaying Approach Medium (see PRR aspects). This signal was on the Panhandle near Chicago in northern Indiana. These were the best light signals ever designed. Not only were they easily readable, but they were very easy on power, and could be operated by primary batteries in isolated locations. Color was not a factor in their aspects. They were used by the Pennsylvania and the Norfolk and Western. In this signal, the main arm has 7 lights, the lower arm 3.
A color-position-light signal on the B&OCT near Chicago. These signals were
manufactured by The General
Railway Signal Company, and were used only on the B&O and associated
lines. This signal is displaying Restricting, and protects a spring switch.
These signals are very bright and distinctive.
If just the two green lights in a vertical column are displayed, the
aspect is Slow-Clear. This signal has a marker light below the main arm,
which indicates Medium Speed when lighted.
Composed by J. B. Calvert.
Last revised 3 August 1999.