That's my guess. I think we have to remember there is no standardization of signaling across railroads. Just safety rules from the FRA the roads have to abide by when devising a signaling system.
One of my favorite aspects of the railroad is the signaling systems and switch control,the signals themselves the bright red/yellow/green,even frost white Wich indicates a speed restriction do to excessivley hot or cold weather wich will effect the rails causing a dangerous situation...🙁😲😲..Frank misssssschief
Does this mean that with PTC, trains can be spaced closer together because you don't have to assume worst-case? The system could recognize that different trains run at different speeds and have very different stopping distances. A 900 ft train in a 13,000 foot block has a lot of buffer. However, it might be able to stop much quicker and the train following it may not be able to stop in time. It seems like a very complex calculation. Adding that maybe one of the trains has electronically activated braking. When anti-lock brakes came out on cars, initially they created more accidents. When the first car has ABS it can stop quickly but the car without ABS behind it cannot stop in time
A relay consists of a solenoid, with a central sliding pin mechanically hooked to an electrical switch. The coil is energized by running a current through it, usually a low voltage e.g. 12V, and the coil magnetically pulls / retracts the slider in. The switch itself is typically connected to a circuit separate from the coil. On a track, the coil is tied into the track circuit, while the switch is tied into the signal system. It is possible for these to freeze up in severe cold.
Very interesting and a classic example how historically simple concepts can get complex & confusing quickly. The industry still seems behind when you note that the technologies associated with GPS systems, automatic driving cars (far from fool proof, but have to deal with traffic pedestrians and turning and lane changes) and flying drones (controlled from other continents) exist with little application to railroading. WE CAN do better.
It is similar to UK signals except every railway company in the US has different railway signaling. Federal wise it's just a simplified version of the British railway signaling system
