So what happens when you can’t see the RR signals from the cab? Two scenarios:
Mountainous regions with many curves, as a result of which you won’t see the signal until you’re only a few hundred feet from it
Urban area where you used to be able to see the signal but then it got obscured (for example, in Chicago on the Amtrak tracks north of Union Station there is an overhead signal bridge right by Des Plaines St. as you’re going east originally it was very visible but due to sale of air rights you can’t see if from the tracks until you’re about 100 ft away from it).
You aren’t just going to have a stop signal pop up out of nowhere without advanced warning (approach signal or end of block limits/track authority). Unless something is majorly wrong. But since we are supposed to be qualified on the territory on which we run - we are to know the locations of all signals.
Part of being qualified on a territory is KNOWING where the signals are.
When operating on a CLEAR signal the train will operate at Maximum Authorized speed until the next signal can be seen. If there is no signal visible where the next signal is SUPPOSED to be, that will be treated as the most restrictive indication that THAT SIGNAL can display (for most intermediate signals that would be Restricted Proceed). If the next signal were to be a ABSOLUTE signal, then the train must be brought to a immediate controlled stop and the Train Dispatcher contacted for instructions.
Where the train is operating on signal indications that are more restrictive than CLEAR, the approach to the next signal must be under more control as it is possible for that signal to display either STOP or a Restricted Proceed indication. Knowing the location of all signals on a territory is one of the primary parts of being qualified on a territory.
Trains in todays world that are operating at maximum authorized speeds are NOT ‘Line of Sight’ vehicles…They cannot be stopped within the range of vision of the operator under most any circumstance. The Signal System and/or Block Authority System (TWC or DTC) give the train the authority of the track ahead.
The theory and practice - most of the time, anyway - is that if an upcoming signal will be more restrictive, then a preceding signal will be encountered ahead and give an indication of that approaching restriction far enough in advance in both time and distance to provide the train with an adequate opportunity to slow down accordingly. Thus, an engineer need not see the indication of the signal until he/ she is right at it - that advane signal is where the stopping (for example) distance is calculated from. So unlike highway traffic signals, not being able to see a signal from afar is not a problem.
Someplace there’s a photo of a signal bridge on the ex-PRR/ PC/ CR/ now NS Pittsburgh Division line which has its signals raised way up so the engineers can see them over top of the highway bridge that’s just in front of them !
if you can’t see the signal you are to assume it to be at its most restirctive, so you stop and contact the dispatcher.
In the mountain situation, the signal system is probably designed so that signals are v\iewable as per need.
As for the Amtrak situation…there could be special rules or bullitens; there could be cab signals in effect; there could be train orders or special messages given to the train crew.
You take the signal as the most restrictive aspect it can give. In this case? Restricting. This is cab signal territory, so those rules do apply as well.
Looking at this picture, I’d say that the crew ought to be paying close attention! If it’s cab-signal territory, a signal that was less than clear probably would have been seen in the cab by the time they encountered the truck. If not a cab-signaled area, and my last signal had been clear, I would have begun to reduce speed, ready to be down to Medium speed as soon as possible (the rule says reduce speed when encountering an Approach signal. If the preceding signal had been an Approach, I’d be planning on stopping anyway. But I suspect that the signal can be seen once the crew got under the overpass–if it’s an Approach, you’re on the right track by slowing down. If it’s a stop (not an absolute), nobody’s going to be upset if you don’t stop short, as log as you can stop short of a train, engine, obstruction, or whatever. In other words, restricted speed.
If my last signal was green, I’m not going to expect the next signal to be red. (Unless I’m delayed in the block, that changes things.)
Sometimes it seems like they go out of there way to locate signals where they are hard to see until you’re right on them. Why place a signal on the straight track when you can place it around the next curve?
Both scenarios - all those mountain grades and curves, and the Chicago terminal conditions - also likely involve slower speeds - say, 35 MPH = 50 ft. per second . So even with those shorter ‘sight distances’ there ought to be several seconds of acceptable visibility of the signal - which ought to be anticipated by a crew that 'knows the territory".
Hey, Sawtooth500, there is another scenario besides the two you gave: Fog! I once saw a train approach a green signal very, very slowly in heavy morning fog, with a crewman on the front porch searching for the signal! They probably totally missed the one before, but now they had the possibility of a red. Once the signal was barely seen to be green, they knew they were good for at least two more blocks.
Sometimes it might be braking distances. If signal ‘C’ is red the train must be able to stop before passing it. A heavy train traveling at track speed approaching Signal ‘B’ on downhill grades and wet greasy rail might need, say, 10,000 feet to come to a stop. If signal ‘C’ is only 9,000 feet away there could be an expensive problem. So, signal ‘C’ is moved on another 1/4 mile which puts it around the curve but 10,320 feet away.
The alternative solution is to go to more complex signal indications so that signal ‘A’ further back requires the train to reduce speed to keep the braking distance within the available B-C block length. But now you have slowed a train down about 5 miles away and in the meantime signal ‘C’ has been cleared to allow it to proceed as usual.
That echoes an article from Trains in the 1980’s about running on the SP over Beaumont Hill or somewhere else in SoCal - I believe it was one of these two:
The Hill
Southern Pacific�s Beaumont Hill
by Caprine, Randall
from Trains February 1985 p. 22
California division sp
This is an interesting photo of the fog problem, which I ran across the other night while looking for something else (1992 was a good year for finding things to mention here, as you may noticed from several of my recent posts):
One winter day on the Seaboard
riding a train through the fog
by Lamb, J. Parker
from Trains December 1992 p. 82
frontispiece SAL
Taken as a telephoto lens picture from the cab of a trailing unit looking towards the front of the train, about all that can be seen is the silhouette of the engineer in the cab door’s window about 100 ft. ahead, and the gray all around - plus the sides of the locos, of course. Prof. Lamb’s caption and comment was to the effect that the safety of the train, those aboard, its cargo, and the people at the grade crossings were th