Motorists have been warned to watch out for new road changes as a £4.1 million scheme of essential repair work at Spaghetti Junction begins on Monday.

The 17-month project to reinforce eight bridge deck supports, repair columns and supporting crossbeams at junction six of the M6, has been described as "essential" to maintain Birmingham’s iconic motorway interchange.

Spaghetti Junction opened 36 years ago this month and is used by more than 160,000 vehicles every day. Last year, the Highways Agency announced plans for repair work to prevent more costly repairs at a later date after concerns over its "crumbling" state.

The Highways Agency and Birmingham City Council have formed a partnership for the project and said they wanted to ensure road delays were kept to a minimum.

The work will be carried out below the bridge deck so as not to affect the M6 motorway carriageway.

However, the Salford Circus roundabout will have an additional lane marked on the outside but will lose the current inner lane during the works. This will maintain two traffic lanes on the roundabout so capacity will be remain the same. The speed limit here will be restricted to 20mph.

In addition, the A38 Tyburn Road heading into Birmingham City centre will have the dedicated left turn lane removed, and the A5127 Lichfield Road heading out of Birmingham City centre will have the existing bus lane reduced in length and the offside lane approaching the roundabout will be closed.

Highways Agency project sponsor Moreblessing Pedhuru said: "The programme of repairs will help to ensure the Spaghetti Junction slip roads supported by these columns continue to provide a safe route for drivers, and doing the work now will prevent further deterioration and more costly repairs in the future.

"We will repair eight concrete crossbeams that support the carriageway above the roundabout at Salford Circus. Four of these crossbeams are sited above the sunken pedestrian area and four on the inner paved section of the roundabout.

"We will install steelwork to support the carriageway whilst the repairs are being carried out. The road markings will be changed on the approach to and at the roundabout to maintain traffic flows, and a reduced speed limit will be in place for the duration of the repairs."