I travel that corridor daily and my exit to home is the Mounts Road exit, right there off and on for the last 25 years.
Click on this map:
https://www.mytpu.org/tacomarail/general-information/tacoma-rail-system.htm
The rails from Lakewood to Dupont to Nisqually was owned by Burlington Northern for occasional use mainly by Ft. Lewis. Some years ago it was bought up by Tacoma Rail.
Big improvements all along the line. Ft. Lewis needed a better link to the docks at Port of Tacoma.
Mainly Amtrak wanted it because, looking at the map, the green-yellow striped rails to the west have a very slow bottleneck and frequent landslides running along the water by Pt. Defiance.
So this upgraded line offered a short cut and straight stretches of tracks, except for these curves.
Normal train traffic is 20-30 mph at the trestle. Many times I’ve seen heavy loads, like armor coming in, going 10-20 mph, and tilting through the curve.
Supposedly Amtrak did a full speed run last week. But cars loaded with people and baggage are much heavier.
Any competent transportation Engineer could easily compute the safest speed for that curve, with any loaded train.
The testing is quite simple, take a heavy train and make a number of passes at increasing speed and record the increased tilting.
It will likely be shown to be human error.
You give some excellent info on the tracks that you are familiar with here, but there are a few details that you are mistaken on.
First, Sound Transit “purchased” the track that makes up the “bypass” from the mainline and they spent over $800 million dollars improving them. Second the Amtrak train that crashed weighed considerably more than a million pounds. The passengers and their luggage weighed less than 18,000 pounds so the train in this case was essentially not any heavier loaded than unloaded.
The “bypass” route was suppose to save the 70 or so passengers who typically are found on this run 4 minutes as compared to the mainline. In test runs it was found that the actual time is slower than the mainline. How the government can spend nearly a billion dollars on track improvements to save around 70 people 4 minutes a few times a day is sort of incredible.
Supposedly there are a few other benefits to the nearly Billion dollars in taxpayer money spent, but no one at Sound Transit seems to be able to articulate them very well so I cannot tell you what they are.
It will most likely be found in the upcoming investigation, that the engineers were being pressured to travel the $800 million dollar bypass section on the route in a shorter time than it takes to takes to run the mainline. Unfortunately, running through the densely populated areas in Tacoma and Lakewood at 80 mph truly is not safe so the train really needed to be pushed when it got into the less populated Tillicum / Ft. Lewis / Dupont area. The pressured engineer was most likely keeping an eye on the clock and not the speed signs and screwed up.
I hope that the whole rotten bunch goes down and not just the engineer. People were put at risk to try and help upper management save face. The taxpayers, the City of Tacoma and the City of Lakewood were all lied to by Sound Transit about the benefits of this project to push it through. The mayor of Lakewood spoke out about the dangers, but was ignored.