Motorists are being warned to expect delays throughout Portsmouth and are being urged to find alternate routes as work is set to continue on the northbound M275.
The work will begin from 8pm on Monday, 19 August, with lane closures in place on the motorway until 5.30am Friday, 23 August.
In order to keep disruption to a minimum work is being done outside of peak times, meaning two lanes will be open out of the city from 5.30am to 8.30pm each day while only one lane will be available at night.
The previous congestion problems caused by waterproofing work on the motorway were because only one lane was running out of the city during peak times. While delays are expected, working with two lanes open during the day will allow a better flow of traffic.
Advanced warning signs have been placed on major roads across Portsmouth to alert drivers of the upcoming work and advising alternate routes to exit the city via Eastern Road and London Road and Northern Parade in Hilsea.
Colas and Portsmouth City Council staff will be on the ground throughout the city monitoring traffic flows in case additional measures need to be taken.
Should traffic problems escalate road closures and full diversions will be put in place to move traffic away the affected areas and clear congestion. This could include closing the northbound on-slip at Rudmore roundabout so the motorway can continue to flow while other traffic heading out of the city is diverted via Twyford Avenue.
Paul Ferroni, asset manager for Colas Ltd, said: ‘The work on the northbound M275 is going to cause significant delays throughout Portsmouth but the essential maintenance work has to be done.
‘Motorists should expect delays, allow extra time for their journeys and use alternative routes to the M275 where possible. If people can avoid travelling at peak times or use public transport it would be a great help.
‘We are doing everything we can to minimise congestion and inconvenience during the work and are very grateful for drivers’ patience and co-operation.
The essential waterproofing work has to be done every 40 years or so. It ensures the bridges keep their structural strength and can only be done in good weather.
A final phase of waterproofing work is scheduled for the M275’s southbound carriageway in autumn, dates and details of lane closures will be announced as soon as they are available.