The normal aspect of a block signal is green, with the block prior to an occupied block displaying yellow (Signals for Operation, Part 2, MR August 2013, among other references). The normal aspect for an interlocking signal is stop (red) (Signal for Operation, Part 3, MR September 2013, among others). Does that mean that the normal aspect for the block signal prior to an interlocking signal is yellow? Seems like it should be.
Bill
correct. but, go this site to learn more than you ever need to know./
http://www.railroadsignals.us/basics/basics1.htm
charlie
Bill,I’ve seen block signals before a interlocking block displaying red and when a train is approaching it goes green or yellow.The interlock signal will give a green or diverging signal such as diverging clear…Operating rules will govern the speed over the interlock switch and diverging route.
In other words let’s say the normal track speed is 45 but,only 35 over the interlock switch and 20 on the diverging route.
The train going straight will reduce speed to 35 before it reaches the switch and will not resume normal track speed until the last car of the train is pass the switch and if going on the diverging route his speed will be down to 20 before he reaches the switch.
Depends on the system. In CTC the normal aspect of control point is stop, until the dispatcher or control operator clears the route. The normal indication for intermediate signals could be “dark” (approach lit), stop and proceed (only clear when the route is cleared) or clear.
Its also easier to figure out signals if you start from the most restrictive signal and work back.
That means that the signal prior to a stop signal will be approach. It’s not that the “normal” indication is approach, its that the proper indication for a signal prior to a stop signal is approach. Outside of a block signal system, yes, the normal position for an approach signal to an interlocking is approach (that may be the only indication it can display). But in a block signal system, the approach signal to an interlocking will be just another intermediate signal and its “normal” indication will be whatever the “normal” indication would be for intermediate signals.
If you have an interlocking where two railroads cross, the ‘normal’ indication may not be ‘stop’ for both lines. If say one railroad’s busy double-track mainline is crossed by a rarely used branchline of another road, the signals may be set up to show ‘clear’ for the double-track and ‘stop’ for the branchline. In the days of signal towers, a train on the branch would have to stop and whistle to request the tower operator allow them to cross the double-track main.
BTW interlocking signals, like the above grade crossing of two roads, often use two-headed signals to clarify that the stop is and absolute stop and not a permissive block signal (where the train can slow down but not actually stop at the signal). Often that would be a ‘dummy’ signal always showing red, so the signal could show green-over-red (proceed) or red-over-red (stop).
All good information and I thank all who replied. But as I think about it, it may all be immaterial for modeling purposes. I’m planning an HO layout in a 23 X 13 room; the distances between interlockings, whether passing siding, yard entrance, or at grade crossing with another railroad, will probably be so short in scale miles that intermediate true block signals will not be needed. I could chop up a length of main line track into 2 or 3 blocks just so I could add some signals, but a train could end up being in all the blocks at the same time.
Bill
Typical problem. No room for intermediates. That means the signaling can get simplified. Model engines don’t have speedometers so exact speeds aren’t identifiable. The difference between 40 and 30 and 20 mph isn’t really that useful. A lot of model signal systems devolve into switch position indicators.
Actually some DCC throttles give the scale speed…You can also slow the train down to simulate a slower speed by simply turning the power pack knob to the left until the train moves slowly.
There is a lot of operating rules we can emulate but,many chooses to ignore that part of operation and run their trains at slot car speeds.
Ya as an ‘oldtimer’ I have to laugh when I read younger folks complaining that their new diesel will ‘only’ go a scale 60 MPH at full power, because they want to go faster than that. I remember when MR locomotive reviews often showed a top speed of 180 scale MPH or more, and guys put a lot of work and money into remotoring and regearing engines so they’d run at “scale speed”. After all, if you have an HO layout with 30" min. radius curves, those curves are so tight that on real railroads the speed would be restricted to maybe 15-20 MPH.
Another problem with fast speeds is that, in a small room, it doesn’t take a train long to make it all the way around the room. I’m modeling a B&O branch line in Ohio so there’s not a lot of opportunity for mountains and tunnels to fold the track back on itself to make a longer main line. In my 23 X 13 room with a peninsula, I will probably have 70 - 80 feet of main line track, point-to-point with a cutoff to allow continuous running. Also, since it’s B&O, the signaling is strictly speed based.
Bill
You will also have those color position signals that were pretty much unique to the B&O with the funky lights on the sides of the masts.
Those were “lunar” lights and was part of the signal aspect.
The B&O signals were much different from the PRR signals. They were a entity unto their own.
True…That’s why I posted the link to the B&O signals-it may say PRR but,the link is to B&O signals.
Looks like the key to understanding B&O’s signal aspects was to understand the position of the lunar light.