Eventually, you reach this list’s conclusion, which lies in an unassuming technical question about the trains themselves. After you have figured out what they will look like, and how fast they will run, you need to give signal engineers two facts about them: how fast they can accelerate, and how quickly they can stop. And you need to make sure that your car equipment engineers keep those values the same until you replace the signal system. Remember, the whole point of having signals is keeping a train going at any given location’s maximum possible speed enough braking distance from its leader to prevent a collision. If your gain acceleration performance or lose braking power without rebuilding your signal system, the whole pyramid of assumptions comes crashing down.

How We Slowed the Subway Down
from ~ uday schultz favicon