[ssl232]

Presumably the road has to be closed for the bridge to travel? I assume this takes place at night.

[shikon7]

During the night, there will be 1 lane open in each direction (one on the side of the bridge, and one on the opposite carriageway), so the bridge can be moved.

[giantg2]

If it's moved slowly enough, I don't see why traffic couldn't drive on it.

[phire]

I guess it's theoretically possible to engineer a bridge that can move with traffic on it.

But this bridge is engineered with solid feet for taking traffic loads. The wheels are only extended for movement and wouldn't be able to take the load of traffic.

[tantalor]

That probably just takes a few hours, easy to do. And you can start/stop a few times to let cars go over.