Railway Signalling and Operations FAQ: Train Order Signals

Railway Signalling and Operations

Train Order Signals

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Dave Pierson's debate with me ultimately led to this page being written, and Dave contributed to it as well.


Train order signals, as should be clear from the name, are signals used to indicate to the engineer that he has to pick up train orders at the location, usually an interlocking tower or station, where the signal is found. With the demise of interlocking towers and local stations, train order signals are now quite rare in the U.S.

Forms of Train Order Signals

  1. Single-lamp color light attached to face of tower.

    Probably the most common type of TO signal recently. Present on at least PRR and NYC towers. Often installed without a face plate.

  2. Semaphore(s) on separate pole very near tower/station.

    This variety was often distinguished by being on a separate pole, with the semaphores for both directions often (usually?) mounted together. Pictures I've seen suggest that the masts are taller than the usual signal mast. Being near the tower, the train order signal was in the middle of the interlocking, rather than at either end.

    Were the semaphore blades distinguished in any way from interlocking signals? What roundel colors were used?

  3. Flashing "O" or yellow lamp.

    Limited to the Pennsylvania RR (? and associated railroads), this was literally a flashing letter "O". The flashing "O" was placed between the 2 arms of the interlocking home signal, to the left of midline. Some locations had a flashing yellow lamp instead of the flashing "O".

  4. Rotating Beacon

    These bacons appear to the author little different from those used on emergency vehicles. They appear to be an obvious admission that railroads no longer create markets, and that the mass market has price advantages. Yellow is the color seen in use by the author at Reading Terminal, Philadelphia, and the Upper Level of Pennsylvania Station, Philadelphia (30th St. Station).

  5. "TO" Marker Plate

    Seen only in rulebooks, these may be signals of various sorts for whom the "TO" plate appears to be the distinguishing feature.

  6. Variant Signal Type for the Given Railroad

    Some railroads used a signal type not found elsewhere on their road for train order signals. One example of this is the Erie, which used (apparently) PRR-style position light signals -- though the lamps are identified as being white, not yellow -- for their T.O. signals. Another example is Boston & Maine, which used 3-light color light signals, oriented horizontally. B&M's mainline signals were of the searchlight type; the T.O. signals appear to have been differentiated by this single feature.

Mark's Railroad-Related Stuff
A Pennsylvania Railroad Home Page
Railroad Books of Rules and Signalling: A Home Page
Train Order Signals

Mark D. Bej, M.D.