That’s what is happening here. The old bridge is still up while the new bridge is being built.
Pensacola’s 3 Mile Bridge took even longer to complete because it sustained major damage during hurricane Sally when two construction barges broke loose from their moorings and collided with the unfinished bridge, knocking out sections of roadway that had already been completed and were being used by traffic...........................
That’s not what is happening here. There is no need to maintain traffic on the old bridge while the new one is being built.