CSX Carlise, OH wreck cause - Trains Magazine

I got it from the CSX Operating Rules Manual, I'm a conductor/engineer. The full definition is much longer than desired for what I hope will be picked-up as a letter-to-the-editor. Restricted Proceed can be indicated by either the actual lights shown on the signal, or by whether the signal is either intermediate or absolute (some railroads use control point or home for absolute and automatic for intermediate), but it means the same thing. An intermediate signal's most restrictive aspect is either restricted proceed, meaning the train can keep moving at restricted speed, or has to stop and then proceed at restricted speed. CSX currently uses restricted proceed, NORAC territories use stop and proceed. An intermediate signal is defined as one that has either a number plate, "G" marker (for grade), or a "P" marker (proceed). An absolute signal has none of the above signs and when displaying an "all red" aspect it means stop, period. An absolute signal can display a restricted proceed aspect as well, but the aspect indicated governs that, not the type of signal it is. Absolute signals usually, but not always, protect some kind of turnout or crossover that is controlled by either a tower or more likely today a central dispatching center. Some of this is redundant under current CSX rules - the "G" marker and "P" marker are really to allow trains to keep moving under stop and proceed rules. Where the Carlise wreck happened was between signals protecting turnouts to a siding, so both the restricted proceed signal they were running under and the clear signal they assumed was for them, but was really for the train ahead of them that they hit, were absolute. (Remember what happens when you assume something!) The crew of Q24316 saw a clear signal almost three miles ahead of them and, forgetting that there was a train ahead of them without a working marker, took it as their's.

As to color, it depends on what type of signal system you're talking about and a particular railroad's set-up. There can be a great deal of difference between signals even on the same railroad. CSX has about 4 or 5 different systems right now, and sometimes the same color combination can mean different things between the systems. I've given passing consideration to someday doing a book on operating practices and signal systems, maybe as a retirement project in about 20 years. Hope I haven't further confused things for you.