5 MPH? If she hit him from behind and the motor car was travelling at 15 MPH, then the accident should have been a -10 MPH collision. Darn space-time continuum.
I think she was distracted and had no idea how fast she was going. To do that much damage which includes flipping the very heavy motor and its crew over on its side like that from behind, it would take the car going 15 MPH faster than the motor - the car going close to 30MPH. That is darn fast for non-gated crossing of railroad tracks. Just a guess...
That's why we have police forensics. They'll figure out the truth. I hope she gets more than a slap on the wrist. She actually injured the motorman. This was no fender bender. I wonder if the D&S could take her minivan, put the steel wheels on it and use it in place of their wrecked speeder? Poetic justice.