[niftich]

Accident site: just west of the Mounts Rd, Old Nisqually exit on southbound I-5 [1] and streetview [2].

Some additional facts, without speculating about cause: the derailment occurred in a left-hand curve -- running timetable southbound, map westbound -- with the latter portion of the curve situated on a bridge above the southbound lanes of I-5. The curve is at the end of a nearly 9-mile stretch of (freshly upgraded) track with long straightaways and gentle curves. The upgraded section of track ends just around 150 yards from this curve.

In the aerial footage of the scene, you can see the lead car and the carriages following it flew off, tangent to the curve. The middle of the train bunched up on the bridge, and the rear half of the train fell inward into the curve.

[1] https://www.google.com/maps/place/47%C2%B004'55.2%22N+122%C2... [2] https://www.google.com/maps/@47.082065,-122.6750448,3a,60y,2...

[sounds]

Thanks! Seattle Times now reports rumors of a collision with something on the track. Since this train was the first with passenger service, that seems plausible.