>>1911822>but having never operated in speed signalling (rarer in NA, I believe Canada and the NEC use it)I can try to comment on that, it's been a while since I've worked on track level in the subways, so the standards might be changed for a good portion of the network.
In this pic, there are two signal heads. The top one indicates whether or not a train can pass and is speed controlled (when a train enters the block, the signal is on a timer. After an allotted time in the block has passed, the top signal will either give a green or an amber light, telling the driver to proceed. If you go too fast, the signal will be red, and you must wait.) We also have Lunar Signals if the track is connected to a yard, or there's multiple junction points. It essentially tells the operator that the next signal is red, due to grade timings, and you may proceed (If you're going at the proper speed!) . The bottom signal indicates whether or not the train will go on its normal route, or the diverging routes. Green means you're on the normal train route, while amber and red means the train will head on the diverging path. So for example, if you see a signal that's green over green, it means a train will run at normal speed on the normal path. Hope this helps.
