Captured with the game paused, since it looks like that only very briefly, while the vehicle is transitioning from the bridge surface to the terrain. Given that the terrain there is a steep dropoff created by precisely-located dumping designations, however, the visual effect is... dramatic. No effect on simulation.

It is also observed at the far end of this same bridge, though less severe- which could be because it's rotated 90 degrees, but it also could be because it's at level 2, or uses a different bridge approach piece (the one at the top is a "level" approach off the cliff face):

Observed Update 4.1 | v0.8.5 (b598).

To reproduce... probably any right-on-the-edge bridge will do, but it's easier to just load up my save and wait- at 1x sim speed, the glitch appearance lasts only a frame or two at higher speeds, it's like 1/4 to 1/2 a second at 1x- for the next truck to exit the bridge. It's a very busy bridge, thanks to that dumping operation and the multitude of trains bringing rock in.

Okay, upon further observation, the pothole behavior seems to be most pronounced, and likely to occur in the first place, when the pathing system is under heavy load. The lower end of the bridge probably experiences less of it because there's so little space for the pathing system to pick a route through.