Drivers have been warned to leave before lunchtime on “Frantic Friday” to avoid the worst of the Christmas traffic, with 1.3 million motorists expected to clog up UK roads on the last working day before Christmas.

Long queues and travel disruption have been predicted for Friday, and rail strikes and fog are expected to worsen congestion during the annual Christmas getaway.

Highways England has suspended 99% of roadwork’s on motorways and major A roads in anticipation of the traffic, with experts predicting that Friday will be one of the worst travel days of the year as leisure drivers fight for road space with regular commuters.

The RAC estimates around 11.5m separate festive getaway trips will take place before Christmas day, and 1.3 million motorists will hit the road.

Boxing Day is predicted to be the most congested day over the Christmas period, with 5.3m separate leisure journeys expected as shoppers head to festive sales.

Fog and poor visibility have been forecast by the Met Office in northern England and Scotland in the build up to the Christmas break, followed by strong winds and heavy rain on Christmas Day and Boxing Day, scuppering hopes of a white Christmas.

Dr Graham Cookson, the chief economist at transportation analysts Inrix, said many motorists should expect to find themselves stuck in long traffic jams from Friday afternoon onwards.

“After lunch, most of the roads will get busier and stay busy into the evening. What we see is roads in congestion for most of the time, average speeds very slow, people crawling along,” he said.

“The pure weight of traffic means a lot of motorways will be much slower than normal so your total journey takes so much longer.”

Inrix data shows that the worst non-accident traffic black spot on the Friday before Christmas last year was the A303 at Stonehenge. There were tailbacks for seven miles when congestion at the notorious bottleneck peaked shortly after 6pm on 23 December.

Asked which routes would see the longest queues this year, Cookson said the M25 was “right at the top of the list”, warning that “it doesn’t matter which way you’re going round it”. The M6 between Merseyside and Staffordshire, M1 and M4 would be “incredibly busy as well”.

Courtesy of the Guardian Newspaper