More than 200 officers are involved in the huge operation. The 50,000-tonne bridge, one of Europe's busiest river crossings, carries 150,000 vehicles a day over the Clyde.

Cameron Buttle reports: "An elaborate operation"

The bridge will close 23-25 October and 30 October-1 November as it is "jacked up" by engineers and moved five centimetres in an operation designed to tackle structural deficiencies.

On both weekends the bridge and the M8 will be closed for 35 hours from Junction 19 (Anderston) to Junction 21 (Seaward Street) in both directions between 1900 on Saturday and 0600 on Monday.

Diversions have been plotted

Up to 11 diversion routes will be signposted and tolls over the Erskine Bridge will be suspended.

Glasgow Council Transportation Manager Marshall Poulton said: "These diversions may be a little longer in terms of distance but will save on journey time and frustration especially if you are travelling beyond Glasgow.

"This is particularly important for those travelling to Glasgow airport.

"I should stress, however, that Glasgow will be open when the closures take place. If people set aside more time for their journeys these weekends and try to take alternative transport there is no reason why they can't complete their journeys on time."

There will also be extra underground services and more carriages on many ScotRail trains on the Strathclyde network into Glasgow during the closures.

The bridge will be raised

The work on the bridge, part of a programme costing £31.5m, is necessary after it was found that the north piers had moved out of plumb by nearly two centimetres.

As a result, the bridge deck had slipped on its bearings and was pressing against the approach structures.

Jacks will hold the bridge deck in place for seven months while the old support piers are demolished and new ones constructed under the deck, using reinforced concrete.