Lancashire County Council had originally planned the full six month programme, which involves closing Curzon Street, to start in June.
But, after considering the effects on the town centre and the possible loss of trade to many independent shops still recovering from the pandemic, a decision was made to start the initial five-week preparations next month and re-schedule the main part of the work to begin in January, 2023.
County Councillor Charlie Edwards, cabinet member for highways and transport, said: "We apologise for the inconvenience this will cause and will do everything we can to keep disruption to a minimum."
The first stage of the project, to carry out essential strengthening work to the bridge, will be a five-week programme to redirect gas lines, which run along the length of the bridge. The work will begin on Monday, June 13th.
The bridge is located under the road on Curzon Street, close to Primark at the T junction where it joins onto Bankfield and the pedestrianised area of the town centre.
Some roads will need to be closed, and temporary traffic arrangements will be put in place while this work is ongoing.
Bankfield will be closed to all vehicles from its junction with Standish Street, except for access vehicles, from the junction with Standish Street and Curzon Street up to the junction with Parker Street. Delivery vehicles will still be allowed into the market hall and Charter Walk.
The pedestrian route will be open on the south footway of Bankfield to Charter Walk.
A signposted diversion route will be in place, as well as changes to traffic on the surrounding roads.
County. Coun. Edwards, added: "This is a major bridge, which carries the highway over the River Brun.
"Its deteriorating condition means it is no longer able to withstand the demands of modern traffic and we have to take action to ensure it remains safe."
The diversion route includes temporarily introducing two-way traffic from numbers 1 to 21 on Standish Street.
The parking bays will be suspended on this section to accommodate the two-way traffic. However, business vehicles will be able to park outside temporarily for unloading.
County Councillor Edwards said: "Business vehicles will still be able to unload on Standish Street between numbers 1 and 21 while the work takes place.
"Two of the four disabled bays are still available on Bankfield. Our highways engineers are happy to businesses if they have any concerns."
After the five week utility diversion work is complete, the temporary traffic management measures will be removed until the next stage of the work next year.
Cheryl Jackson, who owns Cuppa Cake Ltd at the bottom of Standish Street, said she welcomed news of the temporary suspension of the works as it would give her time to make plans for her business.
Cheryl said: "Communication about this issue has been poor and when we heard that the work was due to start next month and the road would be closed for six months it was just devastating.
"At least now we will have the Christmas trading period."