ESSENTIAL REPAIRS to the waterproofing layer on a section of the M6 motorway north of Birmingham are set to cause traffic chaos this summer, with 20 weeks of contraflow.
The Highways Agency is having to carry out the £10M repairs following the appearance since last November of 20 'cooking potsized' potholes on the carriageway near Spaghetti Junction.
Work is needed on a 2.1km stretch between junctions 5 and 6 and 960m north of junction 8.
The potholes are produced by 'implosions' on the carriageway, triggered when surface water is trapped between the road surface and its waterproofing membrane.
Emergency repair work involves stripping the road back to the concrete viaduct and relaying the carriageway complete with a new waterproofing layer.
The affected sections are categorised by very heavy slow moving traffic and this appears to be a factor in pothole formation, although the spokeswoman said it is impossible to predict where holes will occur next.
She said: 'Recurring potholes have caused recent widespread disruption and are becoming more frequent. A sudden unexpected delay caused by attending to a pothole paralyses routes, in, out and through Birmingham.'
And although there will be disruption, 'it will be nothing like the disruption we could expect if this vital work is not done'.
Work starts on 6 June. But activity around Spaghetti Junction, which will restrict traffic to and from the elevated A38(M) Aston Expressway city centre spur, is scheduled for nine weeks over the summer when traffic is lighter.