“Drivers should look to re-route or re-time their journey or use other forms of transport,” says National Highways.

During the first weekend closure of the M25 in March, disruption was minimal. Before the event Jonathan Wade, the National Highways executive responsible for the project, told The Independent that he advised local people to “decorate the bathroom”.

There is concern that after the absence of massive traffic jams last time, the motoring public may be complacent and assume that roads in the area will be clear.

National Highways now says: “We’re grateful to all drivers last time who avoided the closure and completed their journeys in other ways. We urge you to do the same again.

“You should only drive through this area during this closure if your journey is essential as we expect there will be long delays during this time.”

Our travel correspondent Simon Calder reports:

“By Byfleet station we emerged from the pine trees, and found the country calm and peaceful under the morning sunlight.”

I recalled that line – from H G Wells’s War of the Worlds – at West Byfleet station in Surrey as I emerged from the first train of the morning from London on Saturday.

In this leafy corner of the home counties, all was “calm and peaceful under the morning sunlight” – until the first Bulgarian truck came thundering through.

The lorry had been diverted from its planned trajectory by the unprecedented closure of a stretch of the M25 orbital motorway around London.

And the A245 between Byfleet and West Byfleet has become part of a diversionary route – as well, I was to discover, as a temporary tourist attraction:

The M25 normally carries between 4,000 and 6,000 vehicles in each direction every hour from 10am until 9pm at weekends between junctions nine and 11.

Here are some others facts about the motorway circling the capital city:

• The M25 cost almost £1bn in the 1980s
• Two million tons of concrete were used in construction.
• It was first designed to carry up to 100,000 vehicles each day, but now covers nearly double that.
• Construction was between 1975 and 1986, with Prime Minister Margaret Thatcher opening the final section

The RAC advised motorists to avoid travelling if possible and pack extra food and drink if they plan on using the M25 this weekend as stretches of the motorway shut for the entire weekend.

Alice Simpson, RAC breakdown spokesperson, 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 23-27 in Hertfordshire and Essex.

“With weekend temperatures reaching 25 degrees 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 motorway – which is Britain’s busiest – will be closed in both directions between junctions 9 and 10 in Surrey from 9pm on Friday until 6am on Monday while concrete beams for a new bridge are installed.

National Highways senior project manager Jonathan Wade told drivers to leave extra time, follow official diversion routes and to “only travel if absolutey necessary”.

Diversion routes will take cars on a 19-mile journey on A roads, crossing from Surrey into London’s Ulez area, though National Highways has assured drivers “no enforcement action will be taken”.