On the 27 route and that bridge in Bournville, there is a solution available there that would provide minimal disruption. Send the buses prior to the bridge down Franklin Way to Mary Vale Road. Go over the bridge at Mary Vale Road. Then turn Victoria Road into a one-way street northbound, back to Bournville Lane, continue journey.
For the return, from Bournville Lane turn Lea House Road into a one-way street southbound, send buses down there to Mary Vale Road, then a reverse of the outbound route. Profile the corners either end at Victoria Road and Lea House Road to discourage parking and allow the bus a wider turn in.
That's just if you want to maintain the route as close as possible to Bournville station if the bus cannot get under the bridge. The one-way streets would probably make travelling around those roads easier for the residents as well, as there's a minimal amount of disruption involved.
For the return, from Bournville Lane turn Lea House Road into a one-way street southbound, send buses down there to Mary Vale Road, then a reverse of the outbound route. Profile the corners either end at Victoria Road and Lea House Road to discourage parking and allow the bus a wider turn in.
That's just if you want to maintain the route as close as possible to Bournville station if the bus cannot get under the bridge. The one-way streets would probably make travelling around those roads easier for the residents as well, as there's a minimal amount of disruption involved.