Timeline for Why do trains not have a high-friction emergency braking system?
Current License: CC BY-SA 3.0
16 events
| when toggle format | what | by | license | comment | |
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| Feb 8, 2019 at 21:17 | comment | added | Dave Kammeyer | Yes, busses are not designed from a systems perspective to guarantee safety. Still, even within the train framework of guaranteeing safety, the reason you need long headways is poor braking performance. A bus can brake at at least 0.5g, which means 100km-0 in 6 seconds. A typical commuter train takes a full minute. Having poor brakes is not what's giving you the safety advantage of a train over a bus. | |
| Jan 27, 2019 at 0:56 | answer | added | Phil Sweet | timeline score: 0 | |
| Jan 26, 2019 at 14:36 | comment | added | Robert Jack Will | Note that buses don't maintain 10s with the same safety level or speed that subways have. Bus accidents are much more common. And bus headways get closer the slower the buses drive. | |
| Jan 26, 2019 at 14:32 | answer | added | Robert Jack Will | timeline score: 0 | |
| Oct 2, 2017 at 10:28 | comment | added | Mark | I think another issue here is that emergency systems are designed to prevent an accident in an emergency situation - routine operations should rely on the normal systems. If an emergency braking system is installed to allow trains to run at shorter intervals, then the system becomes reliant on the emergency system. | |
| Oct 2, 2017 at 8:43 | history | edited | Dave Kammeyer | CC BY-SA 3.0 |
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| Sep 29, 2017 at 3:42 | comment | added | Jem Eripol | @AndyT, I am not "invalidating" the question. I am looking at the concept of using "rubber" brakes considering all materials around it are made of steel. | |
| Sep 28, 2017 at 14:06 | comment | added | AndyT | @JemEripol - Option 1: Shed 100kph linearly through emergency braking. Option 2: Shed 30kph linearly through normal braking and then 70kph in an uncontrolled collision with sideways forces, overturning carriages etc. This question is completely valid and your comment trivialises it. | |
| Sep 27, 2017 at 15:57 | answer | added | agentp | timeline score: 5 | |
| Sep 27, 2017 at 8:24 | comment | added | SF. | Tramway cars have electromagnetic emergency brakes - long bars that electromagnetically stick to rails creating huge friction. The forces in a train are a couple orders of magnitude higher though. | |
| Sep 27, 2017 at 7:40 | comment | added | Jem Eripol | Yea, I can't imagine the rubber being used in steel tracks. Do trains use hydraulic brakes? | |
| Sep 27, 2017 at 7:35 | comment | added | user6335 | "Rubber shoes" would immediately liquefy before being able to impart any useful braking force. The kinetic energy (we're talking dozens/hundreds of megawatts of power to bring a train to a halt) needs to go somewhere - typically dissipated as heat in most braking systems. Alternatives such as eddy current braking are expensive and somewhat destructive to hardware. | |
| Sep 27, 2017 at 7:28 | answer | added | ItWasLikeThatWhenIGotHere | timeline score: 0 | |
| Sep 27, 2017 at 0:37 | comment | added | Jem Eripol | Higher speed trains need to decelerate slowly, otherwise, the passengers will be injured or their baggage be damaged. | |
| Sep 26, 2017 at 21:05 | review | First posts | |||
| Sep 26, 2017 at 22:11 | |||||
| Sep 26, 2017 at 21:03 | history | asked | Dave Kammeyer | CC BY-SA 3.0 |
