Highways authorities have urged motorists to steer clear of a southwestern section of the M25 from Friday night, when the second planned weekend closure of the London orbital motorway takes place. Tens of thousands of vehicles will be diverted on to local roads when one of the most used stretches of the UK’s busiest motorway is closed in both directions between junctions 9 and 10 to allow for the replacement of a gantry and the construction of a gyratory bridge. The closure will be in place from 9pm Friday until 6am on Monday. Most drivers will be forced on or off the motorway further south-east at junction 8 near Reigate to join a 19-mile official diversion route. Managers at National Highways are concerned that drivers could ignore warnings to avoid the area after the first M25 weekend closure in March passed off smoothly, despite fears of unprecedented traffic jams or “carmageddon”. They insisted there was no room for complacency during the second planned closure, which will shut a longer stretch of motorway at a time of year when more cars are usually on the road. The M25 reopened ahead of schedule after the last closure, when a five-mile stretch was...