Showing posts with label csi. Show all posts
Showing posts with label csi. Show all posts

Friday, June 26, 2009

You Cannot See Through Trees And Walls

Just in case there is any doubt that the operator had very little time to see the stopped train, we go back to the wonder of Google Street View (since I am too lazy to go there myself and take a picture).

Metro Line Of Sight 3The picture below is standing on the bridge on New Hampshire Avenue looking north. The stopped train was actually a couple hundred feet south of here. We are looking north, while the train operator would have been looking from the north towards us. But obviously, if we can't see around the corner to the north, then she could not see around the corner to the south. You can click the photo to see a larger version.

Metro Line of Sight 2Finally, here is another version of the same overhead view showing lines of sight from further back, to the spot where the other train was stopped. The lines pass through buildings and trees. There is no way the operator could have had more than about 500 feet to see the stopped train. The building on the left from the street view is the closest building to the bridge here, barely 200 feet. The building on the right from the first image is the large building near where the train is photographed in the satellite image. It is about 400 feet from the bridge. This is basically the limit of visibility.

But the operator would have not even have been able to see the train from there - the train was stopped 200 feet further south of the bridge, further around the corner and also obstructed by the bridge itself.

Thursday, June 25, 2009

I Scooped NTSB

This is just too good. Today, in the Washington Post:

Hersman said investigators are also examining the actions of Jeanice McMillan, the novice operator of the striking train, who was among those killed in the wreck. The steel rails show evidence that McMillan activated the emergency brakes 300 to 400 feet before the pileup, which occurred on a curved section of track between the Takoma and Fort Totten stations, Hersman said.



From my post yesterday, I said...

So if the second train was stopped a couple hundred feet on the other side of the bridge, just outside the visible line, the operator couldn't even have seen the train until she was within about 500 feet of it!


Who needs dozens of forensics experts when you've got google maps?

Some reports from passengers in the moving train said that they felt a bump of some kind before the impact but don't remember the train slowing down. The bump they felt was almost certainly the emergency brakes being activated, which would be jarring at that moment when first applied, much like slamming on the brakes on your car (your OLD car, the one that doesn't have anti-lock brakes) before it skids. This also indicates to me that the operator reacted about as quickly as is humanly possible given the set of circumstances.