[colanderman]

There are highways in the US that do this with dividers. A specialized vehicle drives over them and shifts them one lane to the left/right twice each day.

[interurban]

A good example would be the Golden Gate Bridge (at least they used to do this, I haven't been to the west coast in several years).

[khuey]

Still does, but it's only over the bridge. The approaches have fixed bandwidth and can back up.