Narrow lanes and a 50mph speed limit are in place, with a free recovery service operating 24 hours a day. There will be additional lane and slip road closures as required, which will be carried out overnight when traffic flow is lowest.
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Wednesday morning's weather for the west of the region
Wednesday morning's weather for the east of the region
A new report into the ever- worsening traffic congestion in Oxfordshire has concluded that the county is in danger of coming to a halt.