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.
More top news
A man has been arrested on suspicion of conspiracy to murder after reports that shots were fired near a Dorset supermarket.
Holly has the latest on today's thundery downpours.
The French Bulldog, a breed popular with celebrities like Leonardo DiCaprio, is an increasing target.