I’ve been wondering about this question for a long time. Every single car in a train has its own brakes, so the train should stop in the same distance that it takes one car to stop. Why is this not the case? Or does each car take a mile to stop on its own?
Cars are (relatively) light and have huge grippy rubber tyres rubbing on a grippy road surface.
Trains are heavy. Even a ‘light’ passenger train can clock in at 40 tons per coach, freight trains can weigh thousands of tons. They have metal wheels making tiny amounts of contact on a metal track. The upside of this is once they get going it’s very easy and efficient to keep them at that speed, the downside is that it takes a mile to stop.
People are saying how cars have tires and your talking about train cars, even with all those wheels, they have to brake at the right speed, because a train wheel with wheel slip is basically on ice, and has next to no grip, add all those cars that weight more than an actual vroom vroom car, and the train has a hard time stopping all that weight quickly.
Tldr super heavy train cars can’t stop the wheels immediately, because it may as well be on ice.
Usually, train brakes aren’t powerful enough to slow down the train as quickly as a car. On top of that, air brakes have a few seconds delay as the braking signal has to propagate from car to car. This is acceptable because there are more effective safety measures that can prevent the need for a train to brake quickly.
However, modern lightweight passenger trains can usually brake a lot quicker, in some cases nearly as fast as a car on regular tires. (If the track isn’t dirty)
It’s the same thing as trains accelerating up to speed, there’s a lot of weight that has to come to a stop.
While yes there is a lot of contact area spread out between all the steel wheels, it’s still not enough to make stopping all that weight, with all that momentum any kind of quickly or efficiently.
IIRC passenger trains (think Amtrak or subways in the USA) have extra braking mechanisms built into the rails at each station to help bring them to a stop (please correct me if I’m wrong)
Freight trains, the big several miles long ones, only have the car brakes and again there is an immense amount of mass and momentum that has to be slowed and stopped. So if they try to stop quickly, all that’s going to happen is the wheels will slide across the rails.
A car use rubber tyres on an asphalt surface. Something which have a lot of friction. This is a good thing when accelerating, stopping or cornering but is generally a bad thing for cruising at the same speed. Trains use steel tyres on steel track. This have very little friction allowing them to only use a fraction of the fuel of a car to move the same cargo over long distances. However it is very bad when accelerating or stopping. If you apply the brakes too hard the wheels just starts slipping. It does not matter if the train is a mile long or just a locomotive or empty car.