Roadworks on one of Southampton's busiest bridges is causing traffic chaos across the city this evening.

Rush hour traffic is being snarled up around the Northam Bridge as improve works to the major commuter route get underway.

Traffic is currently tailed back as Six Dials in the city centre as motorists queue to get home.

Motorists had been warned to be prepared for five months of delays when major roadworks get underway today on one of Southampton's busiest bridges.

Northam Bridge, which sees 35,000 vehicle crossings everyday, is set for £1.2m of major waterproofing improvements.

A series of lane closures will operate for 20 weeks to keep the bridge open throughout.

But Southampton City Council chiefs are still urging people to seek alternative routes and encouraging employers to let their staff work from home in a bid to prevent the city grinding to a halt.

The bridge is the city's latest structure to receive works as part of 'pinch point' funding from the Department of Transport and anticipated to be the most challenging.

The council has decided against fully closing the major transport route which has stood since the 1950s.

Instead, the dual carriageway will be reduced to one lane in both directions and traffic signals amended to 'minimise delays as much as possible.

Northam Bridge is the city's fifth structure to undergo major works.

It follows Central Bridge being reopened following 18 months of improvements.

Councillor Jacqui Rayment, Cabinet Member for Transport, said: “We realise that Northam Bridge is a critical element of our transport and highway network, which is why it is of utmost importance that we protect it and ensure its future sustainability.

“Of course, this means a short period of hardship and we appreciate that these repairs will cause disruptions. I would encourage motorists to please plan their journeys.

“A bridge has stood on this site for over 200 years and it is critical that we repair and protect this one now so that it can continue into the future.”

While work is taking place on Northam Bridge, traffic entering the city from the M27 will be encouraged to use either junctions three or five, rather than seven or eight.

The works will involve stripping back the old road and footway to expose the structure of the bridge and providing a new waterproof layer and road surface to protect it for over 30 years.

The council is working with major employers to reduce travel demand by encouraging people to work from home and travel during off-peak times.

Cllr Rayment added: “Our VIP development projects continue to progress, with the ultimate ambition of providing a robust and flexible transport network, to support businesses within the city to thrive and to encourage further economic investment in Southampton.”

Vicarage Bridge, which is part of the larger Itchen Bridge, will be the sixth and final structure to be worked on later in 2015.