Drivers have been warned to expect long delays as a stretch of the M25 closes all weekend including on what is expected to be the hottest day of the year so far.
The motorway – which is Britain’s busiest – is closed in both directions between junctions 9 and 10 in Surrey.
The closure – from 9pm last night (Friday 10 May) – is due to last until 6am on Monday while concrete beams for a new bridge are installed.
Temperatures today are predicted to reach almost 80F, with a forecast of 26C (79F) in parts of south east England in what would be the hottest day of the year.
Official diversions are taking drivers on a 19-mile journey along A roads, crossing from Surrey into London’s ULEZ area although National Highways said: “No enforcement action will be taken.”
But the highways authority said that anyone who ignored official diversion signs in an attempt to find shorter alternative routes would be liable for the £12.50 daily ULEZ charge if their vehicle did not meet minimum emissions standards.
Failure to pay the charge when required can result in a £180 fine, reduced to £90 if paid within 14 days.
The RAC advised motorists to avoid travelling if possible and pack extra food and drink if they do, with the closures expected to mean long delays for thousands of drivers.
Alice Simpson, from the RAC, said: “As this next M25 weekend closure immediately follows major national rail strikes which could see many more people take to the roads, it could be up to six days of disrupted travel for London’s drivers.
“The closures also coincide with the retrofitting of new emergency areas on all-lane-running stretches of the M25, meaning delays are likely between junctions 5 and 7 in Surrey and Kent and junctions 23 to 27 in Hertfordshire and Essex.
“With weekend temperatures reaching 25C or even higher, it’s likely that routes around the 23-mile diversion will be busy as people make the most of the fine weather and jump in the car for day trips.
“Anyone heading to Chessington World of Adventures, which is close to the official A3 diversion route, should expect delays and pack extra food and drink in the event they’re on the road longer than expected.
“Holidaymakers heading to Gatwick or Heathrow should leave an hour earlier than usual and allow plenty of time for parking and security checks.”
The M25 closure is the second of five planned weekend closures which come as part of a £317 million project to improve junction 10.