Re: Marker/Class Lamps...a diatribe

>Class lights and markers had no meaning while a train was within yard limits. <
Actually, this is incorrect. The failure to respect the display or absence of markers and class lights within yard limits would be extremely dangerous.
YARD LIMITS - The current rule for Yard Limits allows the main track to be occupied without authority, all movements being made at restricted speed (being able to stop within 1/2 the range of vision short of just about anything). Engines (switch engines) are to give way to trains. This is actually a fairly new version.
The version of the Yard Limits rule most common during the train order/timetable schedule era allows the mainline to be occupied without authority, prepared to stop short of another train, switch, etc., but clear of or protecting against any first class train. In other words, the passenger trains could roar straight in to the station, and blast right out at departure with the expectation that all inferior trains would be in the clear.
SUPERIORITY OF TRAINS: Trains are superior by right, class and direction. To occupy a main track outside of Yard Limits, you must be:
1. Authorized by train order as an extra train (displaying white flags/class lights. It is the dispatchers responsibility to be sure that if there is more than one extra train, they are protected from each other. -OR-
A scheduled train (or section thereof) not more than 12 hours behind schedule.
-AND-
2. They must be able to arrive and clear the main track 10 minutes ahead of any opposing SUPERIOR train at the next station; or arrive and clear before a SUPERIOR following train will depart the previous station.
What this means is that before you depart a station, you have to know that any train superior to you has arrived and/or departed. Unless you are the most superior train on the division, you have to clearly identify (by train register, dispatcher or by sight) all other trains. All sections of a train have the same right (unless otherwise modified by train order). If you are in the Yard Limits waiting for train No 2 to arrive before you can leave, and it arrives displaying geen signals (class lights/flags), you can not leave until all sections of train No 2 arrive ( unless you otherwise have right over the next section). This would also apply to any superior train in the same direction; and you can not leave ahead of a preceeding section of your schedule.
If a train arrives without a marker, then the train has not fully arrived. You have to see a marker to confirm that the train is "complete". They could be doubling into the station, or "lost" the rear of its train. (This still applies today.)
Failure to properly identify a train by proper class, schedule and marker (indicating it is complete) often lead to cornfield meets. To make things easier, some railroads used train indicators. (SP was one of the last major freight operations.) 141 would mean train 141, 2-142 would mean the second section of train 142, X483 would mean engine 483 operating as an extra train.
Many may think that SP's ng GE 50 ton in the Owen's Valley was numbered X-1; in reality SP was running all trains as extras by then so it was engine no 1 running as an extra.
Add signal systems or double track and the rules change again. Each railroad had variations on these rules, but the basics stay the same.