The crane's fuse in the maintenance box was defective.
I think fuses are usually in maintenance hatches.
There is another maintenance hatch in the Viaduct (right from the Tunnel).
Use a tool to open it. ?
Maintenance hatches can be opened with a Wrench.
A wrench? Good.
Open the Maintenance hatch at the Viaduct with the Wrench and grab the working fuse. It fits to the maintenance box next to the Crane.