DRIVERS are being urged to ignore their satnavs when a five-mile stretch of the M25 closes this weekend.
Instead, they should follow official signs to make sure disruption is kept to a minimum.
National Highways is shutting the motorway in both directions from 9pm on Friday until 6am on Monday between junctions 10 and 11 in Surrey.
The work, to demolish a bridge and build a gantry, will lead to the first scheduled daytime all-lanes closure on the M25 since it opened in 1986.
Project lead Jonathan Wade said the works would cause an hour’s delays but warned drivers against trying to find a quicker and shorter route.
He said satnavs would take them on to smaller roads, making life a misery for people living in the area.
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He told the PA news agency: "How many people are going to take the initiative and try and use satnavs?
"There's probably a greater risk of congestion by people just doing their own thing and thinking they can perhaps beat the signs and find a shorter or quicker route.
"That will cause further congestion on some of the key junctions so please avoid doing that if at all possible."
CLOSURE IS 'UNPRECEDENTED'
Modelling carried out while the plans were being developed estimated that drivers would face delays of up to five hours without mitigation measures such as urging drivers to stay away and creating diversion routes.
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National Highways believes only around an hour will be added to journeys because of the steps it has taken, which is based on a reduction in traffic of 50%.
But Mr Wade said: “Because it’s so unprecedented, we’ve got nothing to benchmark it against.”
He added: “There’s never been a closure of this nature. We really can’t be certain how many people will heed the messages which we’ve given.
“It’s very difficult to determine right now how effective all our traffic management will be.
“Please don’t travel if you can avoid it.”
The M25 normally carries between 4,000 and 6,000 vehicles in each direction per hour from 10am until 9pm at weekends between junctions 9 and 11.
Four more daytime closures of the motorway will take place up to September.
The project, due to be completed in summer 2025, will increase the number of lanes and make it easier to enter and exit the M25 at junction 10, which is one of the UK’s busiest and most dangerous motorway junctions.