ONE of the busiest sections of motorway in the North-west is to be partially closed - with delays expected for jup to six months.

Thelwall Viaduct on the M6 in Cheshire has been partially closed due to emergency bridge protection measures following deterioration of an expansion roller bearing.

The viaduct carries the motorway over the Manchester Ship Canal and is used by more than 150,000 vehicles every day.

The motorway is carried on two viaducts, with northbound traffic on the original viaduct opened in 1963, and the southbound traffic on the new viaduct, which was opened five years ago.

With immediate effect the northbound carriageway has been reduced to two lanes with just the hard shoulder and outside lane in operation.

From 6.00am on Monday three narrow lanes will be in operation in each direction operating on the new southbound viaduct.

In addition, a single lane of traffic northbound will use the hard shoulder of the old viaduct to maintain access to the motorway from the A50 (Junction 20). Limited slip road closures will be in place at Junction 21 (A57) and drivers are advised to follow the clearly signed diversions.

Highways Agency Area Manager Arthur Ashburner said: "These are emergency protection measures that we have had to take because of the sudden deterioration of a large roller bearing, which was discovered during a routine inspection of the bridge.

"We appreciate that these restrictions may cause severe delays which could last for six months, but these measures are being implemented because the safety of motorists is paramount.

"We need to carry out investigations to fully understand the nature of the problems before long term repairs can be carried out."

To help keep traffic flowing the following measures will be in place:

- 50 mile per hour speed limit

- Electronic message signs to be used to advise motorists in advance

of possible delays

- Extra CCTV cameras to quickly identify breakdowns in the

contra-flow.

- Breakdown vehicles will be in position to remove vehicles as quickly

as possible to help reduce delays.

- Highways Agency Incident Support Unit vehicles will be on hand to

assist the emergency services to help keep traffic flowing.

Motorists are urged to observe the following guidelines:

- Keep to the speed limit - it is there for your safety

- Get into the correct lane in good time - don't keep switching

- Concentrate on the road ahead, not the roadworks

- Be alert for works traffic leaving or entering roadworks

- Keep a safe distance - there could be queues in front

- Observe all signs - they are there to help you

NOTE: All bridges have to allow expansion and contraction during summer and winter weather.

The bearing under investigation is 14 inches in diameter and three feet long, constructed of high tensile steel. In this section of the viaduct there are four bearings, one of which has failed.

The other three are also showing signs of deterioration.