After i constructed the first bridge in Michigan i was able to drive over it.
After the tutorial was gone i playe a short coop on michigan and then alone (single player) again,
Now im falling through the first bridge over and over again, nothing seems to help, restarted the game, and again.
After i falled through i set the truck back and it falls in the garage through the ground, when i get out i cant even drive and the physics of the truck is competly broken.
The truck I used GMC MH9500

Im playing on an xbox one x, I made clips of it, my gamertag is Bjoern222
I dont know how to ad xbox clip over my android phone.

[0_1588103957173_Srunner.mp4](Uploading 99%) [0_1588103998574_Srunner.mp4](Uploading 99%)

This has happened to me too, under the exact same circumstances other than its the concrete bridge south of the Factory further north of the map. I haven't found a way to fix this, but just thought I'd let you know you're not the only one.

Same here I keep falling down bridges and also I can pass through rocks and building. When I'm in the garage truck disappear in the ground...look like the texture is corrupted in file.