WIDENING OF M1 junctions 6A to 10 will reach a critical stage this weekend as demolition of a 1950s reinforced concrete bridge is forcing a 13 hour closure of the motorway.
But football fans heading up to watch Manchester United versus Chelsea at Old Trafford need not worry as contractors say the demolition will be completed by 9am on Sunday morning.
Highways Agency project supervisor, WSP's Jonathan Haynes, said: 'By 9am on Sunday morning the traffic flow will be up to 3,000 vehicles an hour in each direction. Plus Chelsea are playing Manchester United in Manchester, which is bound to have an effect.' Originally the closure was scheduled to take 18 hours, but the project team has shortened it to 13 hours to ease disruption.
Contingency plans have been built in should work run late.
Bridge demolition expert Armac, working for Balfour Beatty/Skanska joint venture, will use 12 hydraulic excavators fi ted with pinching shears to peck away at the deck of Slip End Bridge.
As the structure weakens, the deck will eventually collapse onto timber mats protecting the carriageway below.
The work is part of the Highways Agency's scheme to widen the M1 between junction 6A and junction 10 from three lanes to four.
Armac demolition co-ordinator Noel McLean said that the road closure between junctions nine and 11 will begin at 8pm on Saturday night with the aid of police rolling road blocks.
'By 11pm the site preparation works will be done and the demolition starts, although it is hoped that we'll get it started earlier, ' said McLean.
Slip End Bridge is typical of bridges constructed in the 1950s over the M1. It has a voided reinforced concrete deck, weighing approximately 1,400t, and is supported by three concrete piers.
Four breakers will work on either side of the main deck span with two on each of the side spans. Using 500t of pressure delivered through their shears the plant will nibble away at the deck allowing sections to breakaway and land on the matting below, eventually leading to a total deck collapse.
All three supports will then be demolished, beginning with the central pier. But if work is running late the team will first collapse the central deck and pier section. The side spans can then be collapsed into the banks and the road re-opened.
As a fi al contingency the team will leave the south bound side span of the bridge erected, as the two lanes nearest the verge will remain closed as part of the widening work.