[bobthepanda]

This actually changed fairly recently in 2018 and European rolling stock, including tram trains are allowed under alternative compliance regulations.

Older American regulations favor pure buff strength. European regulations tend to emphasize making collisions impossible by using signalling and automatic emergency stop braking, and then crumple zones and other safety technologies. And the US has ended up adopting similar signalling regulations anyways with PTC, so now it is perfectly fine to allow European rolling stock. We already emphasize safety technologies over buff strength in US car regulations.

https://railroads.dot.gov/regulations/federal-register-docum...

[kposehn]

Interesting - I wasn't aware this covered tram-trains. I was under the impression it only granted the exception to lighter off-the-shelf EU equipment like Stadler FLIRT or Siemens Desiro.

[lmm]

It's the same safety regime - the way tram-trains work (the only way they can work really) is by being compliant with the regulations that apply to regular trains.