More than 20 million vehicles will hit the road this festive period resulting in significant delays, warns connected car services and transportation analytics company INRIX.

The busiest days for traffic are predicted to occur from Wednesday, December 20, to Friday, December 22. INRIX says the worst of the traffic delays could exceed four hours.

In addition to people visiting their family and friends, e-commerce will be a key factor in the increase in cars on the roads, as brands look to squeeze in the last deliveries ahead of the weekend.

Last year, the week ahead of Christmas saw a record number of delivery vehicles hit the roads, and INRIX wanrs drivers to be prepared for a similar situation this year.

Delays are also expected between Christmas and New Year, with Tuesday, December 27, predicted to see significant delays.

The volume of cars is expected to rise due to high street sales, and high numbers of people are anticipated to be out visiting family and friends, or returning home from the Christmas break.

The worst hit stretches of motorway will see three-hour delays on Wednesday, December 27, with high traffic volumes expected around the M25.

Dr. Graham Cookson, chief economist at INRIX, said: “As we head into the Christmas period, when many use the roads to visit family and friends, we advise motorists to use the latest real-time traffic technology to keep up to date with the situation on the roads.

"Drivers would be well advised to take alternative routes or avoid driving during peak times altogether.

“Leaving the house with plenty of time to spare will mean drivers ensure they reach their destinations safely."

Highways England willl aim to reduce congestions by lifting almost 400 hundred miles of roadworks across the country.

That will leave 99% of the motorway and main A road network free of roadworks from 6am on December 22 until 12.01am on January 2.

Melanie Clarke, Highways England’s customer service director, said: “We’re doing everything we can to make journeys as smooth as possible this festive period and that’s why we’re keeping 99% of the road network we manage, free from roadworks.

“Over the past two years we’ve already added 190 lane miles of much needed capacity and that will make life easier for those travelling this Christmas and New Year.”

INRIX analysis of last Christmas showed that, at the peak at around 5pm on the Friday before Christmas (December 23), there were more than 300 traffic jams.

Detailed analysis using INRIX Roadway Analytics showed that the worst traffic jam was a 10-mile stretch of the A5 southbound from the junction (18) with the M1 that lasted for more than hours.

According to analysis of the INRIX Incident Platform, this was due to a diversion that was in operation after a multi-vehicle accident around Watford Gap services closed the M1 southbound from Junction 18 (Rugby) to 16 (Daventry). The M45 east was also closed towards the M1 for much of the day.

The second worst traffic hotspot was on the A303 at Stonehenge. At its worst, traffic tailed back for seven miles for four-and-a-half hours starting at 18:05. This bottleneck was congested for a total of 13 hours on December 23 fluxing in and out of congestion throughout the day.