Drivers are being urged to ignore satnavs and only follow official diversion routes to prevent causing gridlock during an "unprecedented" closure of the M25 this weekend.National Highways issued the alert as it prepares to close a five-mile stretch of the motorway in Surrey from 9pm on Friday until 6am on Monday.The Government-owned company estimates that drivers who follow signs for diversion routes on A-roads will have an hour added to their usual journey times between junctions 10 and 11, whi

Drivers are being urged to ignore satnavs and only follow official diversion routes to prevent causing gridlock during an "unprecedented" closure of the M25 this weekend.National Highways issued the alert as it prepares to close a five-mile stretch of the motorway in Surrey from 9pm on Friday until 6am on Monday.The Government-owned company estimates that drivers who follow signs for diversion routes on A-roads will have an hour added to their usual journey times between junctions 10 and 11, which will be shut in both directions.It is concerned that some may try to find alternative routes via minor roads.The five-mile stretch of carriageway will be closed from 9pm on Friday March 15 until 6am on Monday March 18.