I started the topic distance between block signals and one the people that repiled said don’t get them mixed with interlocking signals but I don’t really know what interlocking signals are???
I’ll take a stab at answering this – interlocking signals are used where two different lines cross each other, such as a BNSF track crossing a UP track. Interlocking towers with an operator on duty to route trains through the crossing and prevent collisions used to be the norm, but automatic signals and Centralized Traffic Control centers connected by computer have eliminated the towers.
Interlocking signals are signals controlled by either an operator or train dispatcher. Interlocked signals can only be operated in a specific sequence in conjunction with the crossovers.
So nedarb, you win either way. If you go for interlocking signals, you get to model the interlocking tower (disused if you’re modern era). If you don’t have an interchange, it seems you’rre in the clear!
Have fun.
Most interlocking towers are gone, or at least the operators are. In the old days the tower housed large levers that were connected by linkages to the switches and signals in the field. The man in the tower would have to throw these “armstrong” levers in the correct order to line a path through the “plant”. If they were not thrown correctly, the signals would not clear. All of the elements of the junction were interlocked, hence the name.
Many interlocking plants are only able to handle one train at a time because there conflicting routes. Others have multiple independent paths allowing more trains to pass through, unless certain routes that cross between tracks are chosen.
Many interlockings today are controlled by dispatchers who route and clear trains through the plant.
interlocking signals are controlled by either an individual signal tower or a distant central traffic control center (ctc). the signals are mechanically and electrically interlocked with the switches so that only signals for a selected route can be cleared and the switches cannot be operated until the signals are restored to their normal position. interlocked signals are not always near an interlocking plant. they could be several miles away. as long as they are controlled from an interlocking plant or ctc center they are interlocked signals. automatic block signals are controlled by the train movements not by a lever. on locations where the traffic can operate in either direction on one track they are controlled by traffic relays so only the signals for the selected traffic direction will be clear and those opposing will be red.
Interlocking can be as simple as controlling a switch from single to double track. There will be signals pointing away from the switch in both directions, and on both of the double tracks. In order to throw the switch, all the signals have to be Stop. After the switch is set, one and only one of the signals governing the route through the switch can be set to Proceed. The other signals are locked to Stop. Seeting one signal to Proceed also locks the switch in position.
Of course, the signals are usually hooked in to more signals, so that there is a Slow indication before the Stop.