How does vehicle driver work?

I’m working on a map, and I have; a prop_vehicle_APC, an NPC_vehicledriver and a couple of path corners.

Problem is, whenever I try to load my map, the ZPC drives full pelt down a road, then over a bumpy displacement full speed, and usually flips.

Does it need ground nodes?

What speed should I set for it?

And how can I ensure that it WON’T crash?

Thanks in advance.