In the game, you can run an infinite number of vehicles through a walking section of your own infantry on a road or other hex, or a vehicle for that matter. The moving vehicles will only suffer a -1 movement penalty each and there will be no traffic accidents whatsoever, whether involving pedestrians or vehicles.
Own vehicle mishaps are limited to e.g fording streams, crossing rough terrain etc.
In the SP universe there is no need for traffic lights, cops, road signs or roundabouts
!
Why should it be any different just because the driven-through element is not of your own nationality?.
Andy