I have a relatively simple HO layout of which the bulk is two track mainline. There is one end loop that is single track to keep things moderately interesting. I am interested in adding signals where the dual track swiches down to one track and vice versa. My question is what type of signal is typically used? I know how to wire these things either using the existing tortoise connections or I might even do it manually. I model the B&O in 1955 and I realize they had their own type of signals. I have looked at what is out there for purchase and the choices are overwhelming and my research has been inconclusive.
Answer depends on how you want the signals to work. Do you just want to display clear for mainline/approach diverging route/ and clear/restricting and approach/resricting other side? Or do you want it to change with train movement? Switch only you could do tortoise contacts, to show train movement, you need block detection of some sort for automatic signaling, manual is an option, depending on if you wanted that… Really, we need more information on how you want it to work. And yes, different types are available, again, depending on how you want them to look/work…
EDIT: Although, for B&O in 1955, it would be either B&O style CPL’s, or semaphores most likely, although other options could also work and be prototypical… Really need more information here…
Signals displayed at the switch are interlocking or HOME signals, they are worked from the tower in conjunction with the switches. In model railroading we generally just power them in tandem with the switch.
In practice, this kind of signal normall displays RED, and then can be cleared after the tower operator has alighned the switches.
Home signals typically do not change after the passing of a train.
BLOCK signals are not associated with a switch, but are used to protect the rear of one train from the locomotive of the following train. These are automatic and are NORMALL GREEN unless the blocks ahead are occupied. RED if the immediate block is occupied and Amber if the immediate block is clear but the next block (or signal) is at danger.
Clearly on a single track line the tower at both ends must agree which way the trains are to run.
It sounds to the LION that you will be happy with a simple HOME signal that will indicate the position of the switch points. That is easy, but it is not a block signal.
On NYCT the block signal is on top and the interlocking or home signal is on the bottom if there is one. If either is red, both are red.
An amber on the lower signal indicated a diverging route, a green on the lower signal indicates the main line. The upper signal displays the block occupancy.
RED means STOP, Yellow means approach: the next signal is red. Green means the next signal is not red. I would do this on my railroad, but I’d need a lot more relays to make it work.
ROAR