3 ms·
Moving block systems are not really new, they just aren't distributed widely.
by p_l 2y ago
Moving block systems are not really new, they just aren't distributed widely.
- londons_explore 2y agoMoving block doesn't allow trains to get closer together than the braking distance. This would.
- bluGill 2y agoThere is good reason they don't do that: trains derail once in a while, your plan means the following train will hit that train and so the accident is worse. Part of the answer to that is better track maintenance. However that isn't a perfect answer and so we need larger gaps. Note that cars on the freeway are normally much closer together than is safe as well. If cars maintained a safe following distance we would need 5 times as many lanes. (you know the massive freeways in Huston that urbanists like to show as bad: that is about the correct size of freeway for Des Moines, Huston needs many more if they want to be a car oriented city)
- TylerE 2y agoI'm not even sure derailments is the worst flaw. As soon as one train has to slow down, you're going to get the mother of all cascading effects - trains are slow to brake, but their acceleration is quite a bit slower than that, and you'll be limited to, at the very best, the acceleration of the slowest train in front of you.
- TylerE 2y agoSaying trains should be closer than braking distance is like saying with devs shouldn’t support https. It’s something no expert in the field wound agree with.
- iggldiggl 2y agoPlus as soon as you need to throw a set of points between successive trains, you're back to absolute braking distance, because a set of point in transit effectively acts as a stationary obstacle.