> Trucks are terrible, pedestrians and bikes have zero impact.

Truck loading is very large, but pedestrians do have a non-zero impact - look at the solid marble steps of ancient buildings, for example.

I think though that the pedestrian wear is only on the roadway surface, rather than structural wear from, say, trucks vibrating enough to crack the bridge or throw off bits of concrete.

That's some pointless nitpicking. Ok, humans have near-zero impact to the point of needing double-digit decades to erode a surface. Happy now?