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Repair work will give Lancaster bridge 100-year lifespan

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It will be the year 2113 before any more major work is needed on Greyhound Bridge in Lancaster.

We might all be using flying cars by then, but the current £4.6m works will ensure the concrete section of the bridge will last for at least another 95 years before further work is required.

The Lancaster Guardian, along with businesses in the city, was taken on a tour of the bridge last week to see the ongoing repair work and find out more about the structure and the reasons for delays.

The bridge will remain closed until mid-September due to it being more damaged than first thought.

It was initially due to re-open in early August.

Lancashire County Council’s renovation project began in January, resulting in diversions being put in place over Skerton Bridge and changes to the traffic system in the city.

The county council said that progress had been good over the first few months, but recent work to restore reinforced concrete sections has uncovered damage that is much worse than previous investigations had shown.

Dave Griffiths, senior bridge engineer at Lancashire County Council, conducted the tour of the bridge.

He said: “With the current rate of corrosion we were looking to install a three tonne weight restriction, which would have restricted HGVs, buses and fire engines from using the bridge in 2019.

“We had always planned to carry out the work after the Heysham link eoad was completed to ease traffic congestion during the works.

“We were fortunate that the next round of Department for Transport (DfT) funding came in straight after completion of that project.”

Mr Griffiths said the bridge’s concrete deck is made up of 19 deck sections.

At the end of each deck section is a break, known as a joint. Joints are essential to allow for movement of the bridge deck. The deck has 20 joint positions.

Mr Griffiths explained: “The waterproofing and joint systems have failed at each of the joint positions.

“This has allowed water to get directly onto the concrete.

“The water off the road brings with it salts.

“The water permeates into the concrete over time and when it reaches the steel inside it causes it to rust.

“When steel rusts it expands, which causes the concrete cover to break off.

“Once the concrete cover has broken off the steel is then exposed and will corrode more quickly.

“The works involve breaking out all the defective concrete at each joint position, replacing any defective steel and then recasting the concrete.

“The concrete is being broken out using hydro demolition, which is a high-powered water jet that removes concrete but will leave the steel clean and in place. We had intended to re-use as much of the existing steel as possible, however the extent of the corrosion was much greater than anticipated so we are now bringing in all new steel.”

The county council and its contractors are also replacing the joint system and renewing the waterproofing.

Mr Griffiths added: “As an added protection against a recurrence of the same problem a cathodic protection system is also being installed.

“The cathodic protection should provide a minimum of 50 years additional protection should the same issues arise again.

“Given that the current issues have taken 45 years to form this will mean it should be at least 95 years before any works of this magnitude are required to the concrete section of the bridge.

“We’re also repainting the bridge, and resurfacing the road from Parliament Street to Carlisle Bridge, renewing and recabling lighting 
columns, and removing vegetation.”

Tom Fyson, development manager for Lancaster BID, which organised the tours for businesses and both Lancaster MP Cat Smith and Morecambe and Lunesdale MP David Morris, said: “The scale of damage where sections of old concrete have been removed was clearly visible and highlighted the urgency of this work to avoid weight restrictions being imposed.

“Lancaster BID is delighted with the efforts the county council have gone to in order to minimise disruption to traffic.

“Once complete we are assured the repairs will last for almost 100 years!”