Yes, I know that, which is why I pointed out those two curves on either side of I-5. Seeing as how that stretch is repurposed track, did Amtrak or BN run a safety study to establish speed restrictions, or that they could even move those long cars through that track?
A lot of industry track and sections like that have restrictions on what maximum car length you can run, speed, and can only run 4 axle locomotives on them.
Had a look on google earth and discovered at least one item contrary to news reports.
The views from behind the blue engine are facing in the direction of travel. The blue engine was pushing from behind. The front engine can be seen ( I think ) partly onto the roadway of the SOUTHBOUND lanes of the I-5. From that you can picture how the train came off at the curve where the investigators are (but they are not ahead of the train’s motion, they are where it came off).
I verified this by checking that the grafitti on the bridge (LABRAT KHAT) was there in Nov 2016 on my version of google earth, and also the highway light before the bridge (although this is “southbound” the view faces west-southwest as the highway curves around from Tacoma to Olympia.
There is no curve beyond the (unreached by train) northbound lanes which are separated by a wooded area about 100 to 200 yards wide. Presumably these northbound lanes are not affected by the accident.