WEYMOUTH Town Bridge is to close for more than two months.
Repair work is set to get underway on September 25, with the bridge closed to traffic until November 30, Dorset Council said.
The work is the second phase of planned repair work on the thoroughfare, after half the bridge was tackled last year.
During the work, welds attaching steel deck plates under the road surface to the bridge beams will be inspected, with defective welds milled out and re-welded.
This will prevent water seeping through the deck to the beams which would otherwise cause damage and affect the operation of the bridge.
Tents will be erected over the work area to ensure it can continue in poor weather and the deck will be blasted clean and then resurfaced before reopening.
During the work, the bridge will be closed to vehicles 24 hours a day, seven days a week, and a signed diversion put in place. Access will be kept for pedestrians on one side of the bridge.
To assist HGVs making local deliveries, a one-way system will be in place overnight from 6pm to 9am.
Delivery vehicles will be directed south into the town along St Thomas Street and north out of town along St Mary Street.
Councillor Ray Bryan, portfolio holder for highways, travel and environment at the council, said: “The bridge has over 2,700 welds attaching the steel deck plates to the bridge beams, and last year, the team replaced 267 on the one half.
“Once they have surveyed the welds on the second half, they will carry out repairs to protect this vital lifting bridge for many more years to come.”
Cllr Bryan added: “It’s a complex process, protecting the historic bridge while maintaining it for modern day traffic, but one that our skilled team carry out carefully and efficiently.
“I thank everyone for their patience as this work is completed.”
The bridge will continue to operate for harbour users, with scheduled lifts Monday to Friday at 8am and 6pm, and a single leaf lift at midday.
Mariners are asked to book bridge lifts by 4pm the day before with Weymouth Harbour office (contact on 01305 838423 or on VHF Channel 12).
It is intended that weekend bridge lifts will return to the normal routine, but there may be a requirement to work on Saturdays, so mariners are advised to check ahead of the weekend.