Bullet Train Derails In China 184
chrb writes "Xinhua is reporting that a Chinese bullet train has derailed, resulting in two of the train's coaches falling off a bridge. This comes only a few months after officials at the Railways Ministry expressed concerns that builders had ignored safety standards in the quest to build faster trains in record time — a claim that was subsequently retracted."
Design difference with TGV (Score:5, Interesting)
My cynical nature seems to be not surprised about "that builders had ignored safety standards", in China.
One thing that should be mentioned is looking at the photos of the Chinese bullet train, is that the design did not inspire itself on one of the key advantages of the French TGV. That advantage being that the bogies are between the carriages and not under each carriage. Apparently the French designed it that way because it reduces the scope of damage due to derailment. The TGV has derailed, but it always derails in a straight line.
ref: Nova: Looking down the track at very fast trains [science.org.au]
Re:Collision (Score:2, Interesting)
Most high speed rail isn't suing this system, because at high speeds it's not sufficient.
On the other hand, this was a 'normal' train, traveling at speeds where block signals are normally in use.
With a power failure at night, a failed block signal might not be detectable though.
In France the TGVs carry explosives (fireworks, basically) to put on the rails one kilometer ahead of a failed train, to warn the oncoming train of a problem. This requires getting out of the train and one kilometer ahead of it in time though.
Re:Collision (Score:5, Interesting)
Actually, it happened on Washington, DC's Metro system two years ago. A problem with a train proximity sensing system resulted in a failure to engage automatic braking on one train when it approached another train farther ahead that had broken down. In that case, there was evidence that the operator, shortly before her death, had attempted to stop her train manually, but didn't have enough advance warning to stop in time. Eight other people were killed, and in response, WMATA ordered operators to run their trains in manual mode at all times.
Re:Design difference with TGV (Score:5, Interesting)
And it works incredibly well. The TGV had several high speed derailment that all caused only minor injuries.
It includes the world's fastest derailment at 294kph (182mph) where only one person was slightly injured.
http://en.wikipedia.org/wiki/TGV_accidents [wikipedia.org]
Signaling system by Hollysys (Score:5, Interesting)
Hollysys [hollysys.com.sg] claims to be the main supplier of signalling and train protection equipment for China's high speed rail lines. There are two separate systems - classic track circuits, and a data link between units at the head and tail of each train to a train control center. Either is normally able to prevent collisions. However, in a power failure, the data link system would probably not be functioning. The track circuit system should continue to work on battery power, or, if that fails, indicate STOP.
Track circuit failures resulting in a false proceed signal are rare, but have occurred. The WMATA transit crash in Washington, D.C. was due to a track circuit failure. The US Federal Railroad Administration keeps records of all reported false proceed signals. [ironwoodtech.com] There have been two recorded events in 10 years of false proceed indications due to lightning damage. [ironwoodtech.com]
Re:Collision (Score:4, Interesting)
well, you can. But the cab-signal system also gives you an advantage, as you have a continuous
A missed Square (double-red, absolute stop, whatever it is rendered as in your neck of woods) should trigger an immediate emergency stop of all trains in the vicinity, cab-signal or not, anyway.
<blockquote><blockquote>Some slower but WAY busier lines also need to get away with the old block system, in order to reduce the spacing.</blockquote> <p>Ah, the good old "throw safety out of the window to increase profits" way of managing things.</p></blockquote>
Well, no. The system removes (actually <b>disables</b> unless a non-equipped or faulty train comes) the static, side-mounted block system; <b>replacing</b> it with a dynamic, moving block system. Each train knows where the previous train is, its own speed (obviously) and the speed of the previous. And of course, the brake distances.
SACEM (and the like) computes the safe stopping distance, and can cause everything from slowing down all the way to hitting the brakes, in order to keep the safe distance held.
The "5 meters" (actually, I saw a couple times even closer) obviously can happen only when one train is stopped (in station) and the next train approaches. Nowadays, they've tuned the system with more space, not because it was particularly unsafe, but because it was occasionally freaking out passengers... The damn thing has been working, cramming LOTS of commuter trains daily for 20 years. It's working fine, thank you very much
Now about joining the trains, it might work, until you want to do things such as stop in station or drive fast between the stations...
Obviously, when trains run their 'normal' 70-80km/h, the software spaces them several hundreds of meters apart. AT LEAST (dunno what the emergency braking distance from 80km/h for a MS61 or MI2N is, but the commercial deceleration is enforced).