Hump Signals control the movements of trains in the yard, mostly when the trains are shoving into the yard. Some yards have an actual hump, like Bailey Yard (UP/North Platte NE), Argentine Yard (BNSF/Kansas City MO), or Conway Yard (NS/Pittsburgh PA), while others, like the former Western Maryland yard in Hagerstown MD, are flat and they would make up trains without the use of gravity.
Hagerstown MD -- CSX
A hump signal used in former Western Maryland yard. The signal uses a standard auto type signal head with four aspects. Although the Western Maryland did not have a hump in Hagerstown, this signal nevertheless controlled the engines making up trains. B&W print photo from October 1973.
St Paul MN -- CP Rail
A unique signal used at the south end of "Pigs Eye" yard in St Paul MN. Note that the signals used on the bridge are dwarf PL's. The full size picture to the right was taken in 2001, the other two in 2006. Wish I had then, the camera I use today :-)
A big thanks goes to
Mike Smeltzer of Chicago for the additional
info on these signals:
The signal you are inquiring about is called a Shove Signal.
It is at the East end of Dunn Yard on the Arrival tracks and is for inbound road trains when they are shoving into the yard. The lights are used to protect the shove without having to have a man on the point of the shove or someone at the west-end watching the shove. If you look closely at each signal you will see 4 lights. Each light represents 4 car lengths. AAR specifications for a car length is 60ft. When the track is clear at the west-end all 4 lights will be on. Altho this doesn't mean that the track is clear it indicates that there is 16 car lengths open at the west end of the track. When a train shoves westward into the track, as the hind car hits the first circuit, 1 light will turn off, indicating that there are 12 car lengths to a stop. As the train keeps shoving and crosses the 2nd circuit, light 2 turns off indicating 8 car lengths left to a stop. Same for the 3rd circuit. When the 4th light turns off, the train stops.
If you look at the picture, tracks A, C and E have 16 car lengths clear at the west-end. Track D has 12 car lengths left. Track B has no room left. Track B is used as a lead for the hump so anytime they are humping all lights should be out as the track is occupied with the humper.
I love trains, and I love signals. I am not an expert. I do these pages because I love spending my time doing them - although I do a reasonable amount of research to make sure the information presented is accurate! :-) :-)
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concise graphics, and they do a really good job of showing you where
tourist type attractions are, although they too lack the railroads.
Other notes about specific areas will show up on that page if known.
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