The bridge, in Wednesfield, is an important link in the local road network carrying the Lichfield Road over the Wyrley and Essington Canal.
And the action comes following concerns from residents about their security on a pedestrian diversion route through Wednesfield Park, and from businesses about the impact on their pre-Christmas trade.
The repairs will take around 21 weeks from Wednesday 30 November - a timeframe selected as the Canal & River Trust only allow the canal to be closed between November and March.
The bridge was originally due to be closed to everyone for the duration of the works.
But discussions with the contractors and extra investment will now see Pinfold Bridge remain open, under traffic management, to vehicles and pedestrians until after Christmas.
One lane of the bridge will remain operational to vehicles, including buses, with two-way traffic lights in place.
The bridge will fully close to vehicles from January when demolition of the old bridge deck begins.
However, pedestrian access will be maintained by means of a temporary footbridge to be erected alongside the existing bridge.
City of Wolverhampton Council Cabinet Member for City Environment, Councillor Steve Evans, said: "We have taken on board the concerns of local residents and businesses and decided to invest extra resources to develop a solution.
"This has been achieved thanks to the co-operation and flexibility of the contractors and we hope we have found a way forward that is satisfactory to everyone.
"The condition of the bridge has dictated this work on Pinfold Bridge must be carried out now.
"Investigations have shown that water has corroded the beams of the bridge and part of the brickwork has cracked.
"Replacing the bridge is absolutely essential if we are to keep Wednesfield town centre moving and easily accessible for people."
The pedestrian diversion route through Wednesfield Park will remain an option for people to use as the temporary footbridge will have to be closed on occasion for very short periods of time in the New Year.
There will be temporary night time lighting in place through Wednesfield Park for the duration of the works.
From January, vehicle diversions will be in operation, with vehicles redirected along Lichfield Road (B4484), Lakefield Road (A4124), Wednesfield Way, and Neachells Lane, and vice versa.
Also at this time, public transport operator Transport for the West Midlands will be putting in place temporary bus stops at alternative locations, for the remainder of the works.
- released: Friday 25 November, 2016