In NY State, part of the Thruway collapsed in 1987. The bridge over the Schoharie creek. Poor design of the bridge foundations.

Schoharie Creek Bridge collapse - Wikipedia, the free encyclopedia

Almost immediately, an exit was created on both sides of the bridge and traffic was diverted to NY-5S. After about 1 month, the traffic lanes were diverted to an old railroad bridge and the NY-5S bridge while construction replaced the main bridge.

Maybe something like that can be done.

Here is the area

http://forums.pelicanparts.com/uploa...1369414467.jpg

I've marked in yellow where the temp road was built

http://forums.pelicanparts.com/uploa...1369414481.jpg