contraflow

a temporary arrangement in which traffic travels in the same directions on both sides of the road

I understand that in the UK, “contraflow” has a different connotation. Over there, it means traffic going in both directions on one side of the road. But over here, we use it to refer to traffic going in the same direction on both sides of the road.

That's pretty much the opposite definition. Then again, we Americans drive on the wrong side of the road anyway.

Contraflow (American-style) is used to provide greater highway capacity when evacuating a large urban area. In the summer of 2005, it was used to evacuate New Orleans for Hurricane Katrina and to evacuate Houston for Hurricane Rita.