Drivers are facing months of serious delays as the A338 between Wantage and Oxford is due to be closed for up to six months while Network Rail electrifies the Didcot to Swindon main line.
Vale of White Horse District Council is now pushing for clear plans to be put in place to ensure the local economy, residents, and commuters are not badly hit by the works.
From next month, the road will be closed for Network Rail to raise the Station Road bridge at the closed Volunteer pub near Grove.
The next quickest route available to motorists travelling to Oxford or Abingdon would be by taking the A34 as far as the Milton interchange, near Didcot.
The district council has said the work could result in motorists being required to take up to an 18-mile detour, with cyclists facing a diversion of up to six miles.
Council leader Matthew Barber said: “Motorists and users of public transport in the Vale already experience significant delays to their journey on a regular basis.
“Unless a robust plan is put in place during the electrification work, including the installation of a temporary bridge, we are going to have major problems which would significantly affect many people living and working across the district.”
The work is part of Network Rail’s £1bn electrification scheme, installing overhead wires to power trains on the Great Western main line from London to Bristol by 2016. A total of 27 bridges in the county will need to be raised.
Oxfordshire County Council, the highways authority, has received plans from Network Rail to close the A338 for six months and is considering the application.
Council spokesman Martin Crabtree said: “The county council has not yet received a formal application from Network Rail to close the A338 for six months. We are still considering the situation and will be working with Network Rail to see if alternative options are available which would work better for road users and the local community.”