Whitchurch Bridge closes today (Thursday)
The privately owned bridge, which is used by 5,800 vehicles during a typical working day, closed at 6am this morning and is expected to re-open in April 2014.
During the closure, the 111 year old bridge, owned by the Whitchurch Bridge Company, will have new girders and piers installed.
The bridge straddles the River Thames and serves as the boundary between Berkshire and Oxfordshire, and both West Berkshire and Oxford councils have agreed to parking restrictions and diversions while the work takes place.
The Goring and Streatley Twitter account has said that the area has been littered with traffic cones in expectation of the "carmageddon" while the diversions and restrictions are imposed.
Temporary yellow lines and waiting restrictions will be in place on Streatley high street as well as temporary parking alongside the high street to ease congestion.
Temporary yellow lines and restrictions will also be in place in Pangbourne to manage higher levels of parking.
A series of diversions will be in place with traffic being diverted through Streatley and via the Caversham Bridge.
The number 142 bus route from South Oxfordshire to Reading will also be diverted.
Traffic light phasing on the Streatley A329 and B4009 crossroads has been altered to cope with the extra traffic.
Traders in Pangbourne have previously raised concerns over what impact the closure will have on business in the village.
West Berkshire Council’s executive for highways, Pamela Bale (Con, Pangbourne) said: “"We have done everything we can in order to try and minimise the disruption caused. We are hoping the re-construction of the bridge will proceed according to plan and this will all be as smooth and as less disruptive as possible.
“Pangbourne will continue to be 'open for business' during the construction period, and businesses, residents, and local schools have made plans for the next few months."