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Comment by qzcx | Hacker News Reader

Most train systems I've taken don't have to stop at stop lights, but the buses I've ridden, even with a dedicated lane, still stop at the lights. This means twice as many stops and starts. Big negative in my mind. But then again, maybe this is another small improvement which could be made.

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The stop lights for a train are scheduled such that the train doesn't need to stop if it is keeping to the schedule. This works on both smaller and larger lines.

The stop lights for a bus are scheduled in line with the general car population, so it's pretty hard for the bus to keep to its schedule. There's a lot of work goes into timing traffic lights (for cars), how much of that thought process involves keeping the number 49 on time?

I think perhaps what the parent comment meant was more that trains aren't inhibited by normal traffic lights; upon approaching a crossing with a road, the train is immediately given the right-of-way — i.e., the lights activate, the gates close, the cars stop and allow the train to pass.

True, there is a separate signal for the train, though it's more if the train(s) ahead of it are keeping to schedule than the train itself. (Rush-hour trains here are regularly delayed due to the train ahead of the one I tend to ride being so delayed.)

Where I live, the traffic lights know about approaching trams and buses and turns green early or remains green until they have passed. That doesn't work if the traffic gets too bad, but most of the time it works pretty well.

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