My subs at Sharma&Associates have performed much of the mechanical modeling. They make the auto coupler to handle the brake pipes, ECP and coupler. The pneumatically controller cutlever mechanism is activated by an embedded CAN controller I designed for the purpose. The auto-anglecock is an off the shelve electrically driven valve interfaced to my CAN controller. A similar approach is taken for the brakes. I have modeled the CAN bus using a tool from Vector to make sure I've covered all the bases. The actual CANopen library for the PIC microcontrollers comes from port GmbH (Germany). I found their package to be easier to move between Linux and the PIC microcontrollers.
Oh, engineering-level sims.
I was wondering about system-of-systems level.
Still, fun stuff!