Long-awaited work to introduce lower speed limits on the Orwell Bridge that should dramatically cut disruptive wind closures is to get going this month, with anticipated completion by mid-March.

Highways England is to begin installation work from Monday, January 25, which includes new electronic signs that can display changeable speed limits, as well as work on new speed cameras and road markings where necessary.

The £1.7million work is set to take seven weeks, the authority said, and will necessitate some road closures while work is underway.

It follows a nine-month aerodynamic study carried out in partnership with City, University of London, as well as additional work in the wind tunnel and with computational fluid dynamics (CFD) – technology used by Formula One teams in testing the aerodynamics of their cars.

Necessary legislative work has already been completed.

Currently, the bridge must close when wind speeds reach 50mph or more, which results in traffic being diverted through Ipswich and causing gridlock on the town's roads. Business leaders estimate it causes £1million worth of economic damage to the town each day, while journey times for motorists escalate dramatically.

The new measures will mean cars can continue using the bridge in those high winds, but must drop their speed to 40mph. That will mean the threshold for the bridge's closure is raised to 60-70mph.

Ipswich MP Tom Hunt said: "It's good this is happening now despite all the delays and frustrations, so it is positive.

"Orwell Bridge closures were incredibly frustrating for Ipswich residents but also very damaging to local businesses, and we know local business have been hit very hard by Covid-19.

"When we overcome this public health challenge we will be looking to recover economically. It couldn't come at a more important time."

Mr Hunt said that the opportunity for more freight coming through from the Port of Felixstowe now the UK has left the EU meant it was also imperative to prevent disruptions from the key movement of traffic to and from the port, and also vowed to keep the matter on the agenda for the Ipswich transport task group of town leaders.

"We hope this is the solution to the problem but we need to see this in practice, so I will be keen to keep it on the agenda for a fair while to have regular checks in making sure it is having the desired effect."

For safety purpose, the bridge's eastbound carriageway between junctions 55 and 58 will be closed between 9pm and 5am for five nights from Monday March 1 for work to take place.

A closure of the westbound carriageway is then planned for the same hours from March 8-12.

Diversions will be through the usual routes along the A1214, Yarmouth Road, Chevallier Street, Valley Road, Colchester Road, Woodbridge Road and Main Road before connecting to the A12.

After the results of its study were published last year, Highways England announced it would be pursuing the lower speed limits as a priority, but other measures also to be assessed included keeping traffic going in the middle lane of each carriageway, where the wind had less of an impact; work to establish whether the eastbound lane could remain open entirely as it was also impacted less than the westbound lanes and investigation for parapets work on the side of the bridge.

The bridge, opened in 1982, is a key route both locally and nationally connecting the Port of Felixstowe with the Midlands and the North, with 60,000 vehicles travelling on the bridge each day.

Martin Fellows, Highways England regional director, said: "We understand the vital importance of the Orwell Bridge for people living and working in Ipswich, and also for the people and businesses that depend on goods arriving and leaving the UK at the Port of Felixstowe.

"We will be installing new digital message signs that will display a 40mph speed limit on the bridge when it is windy.

"This will allow traffic to still use the bridge even if there are strong winds of between 45 and 60mph, rather than the current 50mph wind speed limit.

"This means that we are more likely to be able to safely keep the bridge open even if it is windy, and means less congestion in town."

Councillor Andrew Reid, Suffolk County Council cabinet member for highways, said: "The effect of wind-related closures on the Orwell Bridge are well known and incredibly frustrating for people travelling in and around Ipswich, as well as those traveling to and from the East of the county, including the Port of Felixstowe.

"As the local highway authority for the non-A14 roads, we very much welcome the solution of the digital speed signs to allow traffic to cross the bridge safely at a reduced speed when there are strong winds. Closing the Orwell Bridge can cost the local economy up to £1m per day and this cannot continue to happen."