Washington subway crash

[sugarpop]

Originally Posted by classicman

ok, fine if thats the case - find out who is in charge? "insert name here" Now cut his or her balls off. If its a committee, make a party of it and do them all. Our leaders NEED to be held accountable again.

Yes, and we NEED to spend on aging infrastructure! WTF is WRONG with people in power?

[ZenGum]

Originally Posted by sugarpop

Yes, and we NEED to spend on aging infrastructure! WTF is WRONG with people in power?

Simple.

Build a flshy new sports stadium = lots of publicity = votes.

Maintain and repair the stuff you already have = boring = look like you're doing sod all = no publicity = no votes.

, but what ya gonna do?

[Elspode]

Flashy sports stadia generate money for the teams inhabiting them, therefore they generate campaign donations for the election of people who got them built.

Infrastructure doesn't generate enough ongoing profit for those involved. Infrastructure is more along the lines of a one time bribe or graft under the table to secure the contracts, get it made into a Davis Bacon project so the unions get their cut, that sort of thing.

[xoxoxoBruce]

Originally Posted by Elspode

Infrastructure doesn't generate enough ongoing profit for those involved.

But it does provide ongoing employment for kin and hacks.

[glatt]

So the investigators yesterday came out with a little more information.

They confirmed that this particular train was in automatic mode, and was being driven by the computer. They also confirmed that the emergency brakes had been applied. The button had been depressed in the driver's cabin, and the brakes themselves had the bluing that you would expect from emergency application. Also, the tracks had "skid marks" on them.

What they didn't say was how long the skid marks were, or how early the brakes had been applied.

It's frustrating that they didn't include this important information, so I tried to figure it out myself.

If you go to Google Earth and look at the accident scene, you can measure from the point of impact back in a straight line until that straight line gets obstructed by something, and then you know how far away the driver should have been able to see the stopped train. When you do this, you will see that the accident happened at a curve, under a bridge, and the visibility was actually pretty bad. The driver, if she had been paying 100% attention to the track in front of her, would have first seen the corner of the stopped train when she was about 355 meters away. At that particular location, according to the Washington Post, the train speed limit is 59 miles per hour. A train traveling at 59 miles per hour will cover 355 meters in 13.5 second. She wouldn't have seen the full train until she was about 160 meters away or 6 seconds from impact.

I don't know how long it takes to stop a train traveling at that speed. In normal operation, the trains take a while to stop, but they are trying to do it gently for the passengers' comfort.

So she had 13.5 seconds to see the stopped train, realize it was stopped, notice her own train wasn't stopping, still wasn't stopping, and slam on the emergency brake. She did all those things, but apparently not fast enough.

The head of Metro said that there is no evidence that she did anything wrong. But autopsy results, blood tests, cell phone, and texting records haven't been released yet.

The train had an unusual configuration. It had a lead car that normally isn't used as a lead car. In theory, it should have worked fine, but trains were seldom set up that way. And that lead car was overdue for brake maintenance. It's possible that the unusual configuration caused the autopilot to misread the situation and not stop.

I mentioned multiple layers of failure before. We now have: unusual train configuration, possible bad brakes, train stopped on a curve, and a "driver" who may have taken a couple seconds too long to apply the emergency brakes.

[TheMercenary]

Originally Posted by glatt

So she had 13.5 seconds to see the stopped train, realize it was stopped, notice her own train wasn't stopping, still wasn't stopping, and slam on the emergency brake. She did all those things, but apparently not fast enough.

The average emergency reaction time is something like 0.25seconds, or something to that effect as I recall. See event, process, take action.

This is an online test where you test your own:

http://getyourwebsitehere.com/jswb/rttest01.html

[glatt]

I think it's much different in her situation. This is nothing like driving a car and seeing something in the road ahead that you need to avoid.

The train is computer controlled. She is not supposed to take control of the train unless there is an emergency. Her job is to announce the upcoming stations, and close the doors when it's time to pull away from that station. She would get in trouble if she took control and there was no emergency. If she slams on the brakes, she's committing to an action that is going to disrupt the red line during rush hour. She's got these competing directives in her brain. Keep the train going on time. Don't do anything to slow it down and mess up rush hour. Her experience (which was limited by the way - she'd only been a train operator for 6 months) is that the train has always slowed down on its own in the past.

So she needs to make a judgment call about whether it really is an emergency. After a few seconds it was clear to her that it was an emergency, and she hit the panic button.

[Shawnee123]

Originally Posted by TheMercenary

The average emergency reaction time is something like 0.25seconds, or something to that effect as I recall. See event, process, take action.

This is an online test where you test your own:

http://getyourwebsitehere.com/jswb/rttest01.html

I averaged 0.2406. The kid who hit me might get 78.345.

[glatt]

I found an official aerial map of the sight distances, similar to the one I whipped together in the days after the accident on Google Earth, looking for answers that nobody was providing.

So of course, I had to see how close I was in my armchair analysis.

I wrote that:

Originally Posted by glatt

If you go to Google Earth and look at the accident scene, you can measure from the point of impact back in a straight line until that straight line gets obstructed by something, and then you know how far away the driver should have been able to see the stopped train. When you do this, you will see that the accident happened at a curve, under a bridge, and the visibility was actually pretty bad. The driver, if she had been paying 100% attention to the track in front of her, would have first seen the corner of the stopped train when she was about 355 meters away. At that particular location, according to the Washington Post, the train speed limit is 59 miles per hour. A train traveling at 59 miles per hour will cover 355 meters in 13.5 second. She wouldn't have seen the full train until she was about 160 meters away or 6 seconds from impact.

According to the official map, drawn by people on the ground with survey equipment, the stopped train was partially visible at a distance of 1,118.2 feet (or 340.8 meters.) I said it was partially visible at 355 meters. The official report said the train was fully visible at a distance of 471.0 feet (or 143.5 meters.) I said it was fully visible at 160 meters.

I had been measuring from the position of the crashed trains, and it turns out the stopped train was pushed down the track about 3-4 meters by the impact, and I hadn't accounted for that. So my calculations were pretty damn close. Much closer than I expected.