A £20MILLION scheme to save two of Hampshire’s busiest road bridges from crumbling is set to get underway next month.

Transport bosses say without starting “essential” work to the Redbridge Causeway, heavy lorries may be banned from using it within a year.

But the scheme, dubbed the “biggest road maintenance project in Hampshire’s history”, will mean major disruption for the tens of thousands of drivers who use it each day.

Hampshire County Council say it will have to close the A35 westbound for as many as seven weekends while it carries out the work – scheduled to begin on Saturday, November 4

It will force drivers travelling from central Southampton to Totton to take a 15 minute diversion, onto the M27, in order to get to the Hampshire town.

Non-motorway traffic, including moped riders and learner drivers, will have to travel through the city and up as far as Romsey before cutting back down to Totton.

Transport chiefs say they are being forced to carry out the work now as the westbound Redbridge viaduct, which was built in the 1960s, has begun to deteriorate.

Experts say the bridge’s joints are leaking salty water through to the base of the structure, which has now begun to crack, exposing its metal supports.

The county council’s chief engineer for highway structures, Brian Hill, says the bridge is in such a bad state that the authority would be forced to impose weight restrictions.

He said: “It’s one of the biggest bridges we have in Hampshire and it’s one of our busiest so we had to prioritise this project.

“If we didn’t do something now we would have to impose weight restrictions on the heaviest lorries and then buses and eventually cars.

“We are not taking this lightly and we know it’s going to cause disruption but it will be better than closing it off all together in the long run.”

The first phase, costing £1.2million, will involve replacing 21 joints on the westbound bridge.

The work is set to begin at 8pm on Saturday, November 4, when the bridge will close for westbound traffic from the Redbridge Roundabout to the Rushington Roundabout in Totton.

It will remain closed until 5am on Monday, November 6 – although cyclists and pedestrians will still have to access the bridge throughout the works.

Another closure is set to take place the following weekend, before work is postponed for the Christmas period.

Weekend work is then scheduled for the same times throughout February, and the first weekend of March.

While that work is being undertaken on the bridge, teams will also complete maintenance work on the westbound Totton by-pass.

This will include resurfacing the entire road, from the bridge to Rushington Roundabout, as well a sign cleaning and litter-picking.

Mr Hill hopes the work, which will be carried out by the council’s new highway contractor, Skanska, can be completed in just three of the seven scheduled weekends.

However he added that it would not be possible to tell until work begins in November.

Once completed, the team will then schedule work on the base of the structure.

Mr Hill said he hopes that work, costing £7million, will begin next summer.

However he anticipates that the work will not lead to more disruption for drivers.

The remaining £12million will be spent on further repairs, including maintenance work to the eastbound bridge.

However the council says it is yet to acquire the funding for the project, after two bids to the Department of Transport (DfT) for the entire £20million were turned down.

Mr Hill says the initial £8million for the westbound project was gathered through re-prioritising money from other schemes across Hampshire.

He added that his team would continue to apply to the DfT for the remaining £12million.

Councillor Rob Humby, executive member for environment and transport at Hampshire County Council, said: “The Redbridge Causeway over the A35 in Totton is a key route leading to the port of Southampton and a significant trade gateway for the UK.

“It carries significant tourist traffic to the New Forest and is the only major non-motorway crossing of the River Test.

“It goes without saying that doing nothing is not an option here.

“It’s imperative the bridges are repaired urgently to avoid lane closures or restrictions on heavy goods vehicles.”

Hampshire County Council ward member for Totton, David Harrison said he thought the work was necessary, but urged the council to communicate with local residents to minimise disruption.