Block Intermediate

On a section of single line, it is clearly a bad idea to have two trains proceeding in opposite directions, but there is nothing stopping several trains following each other in the same direction. To do this, intermediate signals have to be provided, to keep the trains separated:

However, the normal signalling system in R3D will happily send two trains into the section from opposing ends, resulting in a Mexican standoff when the two trains are held at intermediate signals.

The Block Intermediate option in the Signal dialog tells the signalling system that a train should not be routed to the signal if a route in the opposite direction has been somewhere set between the Block Intermediate and the next signal. The check will cascade down a series of Block Intermediates, and will prevent a route being set to the first one if an opposing route is present anywhere in the section.

In the above example, Block Intermediate would need to be applied to M250, M251, M260, M261, M270 and M271. If a route is set to M270 for an Eastbound train, there will now be an opposing route between M271 and M281, preventing the route being set between those signals - the Block Intermediate option now prevents M261 setting a route to M271 as a result of this. Due to the cascading feature of the option, if a route is set to M251, all three of M251, M261 and M271 will check for opposing routes.

wst9/M281 do not need the option set as there is no opposing intermediate signal between these and the end of the single line - once a train is approaching these, it is not possible to signal a train to M270 under any circumstances. However, there is no harm in setting the option - it won’t affect the running.

This option provides the same functionality as the scripts described in Single Line Auto Sig. The scripting solution may still be worth investigating in some of the more complicated examples given in section 6.