Britain’s motorways are so congested the average speed of drivers is just 25MPH in some areas

Britain’s motorways are so congested that the average speed is only 25mph in some areas, official figures reveal.

The slowest sections are two stretches of the M25 leading to the Dartford Tunnel.

Next slowest is a northbound stretch of the M5 at junction 2, near Birmingham, where drivers endure average speeds of 26.7mph.

The findings emerged from an analysis of Department for Transport (DfT) congestion figures in 2018. 

The average speed is calculated by DfT experts taking speed observations from a sample of cars across 24-hour periods throughout the year.

They work out an average over an entire day, which means some speeds during the rush hours will be even slower.

Where the slowest average speeds in the country are 

In all, there are 17 stretches of motorway where average speeds are below 30mph. The start of the M4 heading west out of London at Chiswick has three separate stretches in the top ten worst sections in the country.

Many slow areas are in the sections of a motorway within a junction between one slip road where motorists filter off and another where vehicles enter the carriageway. The worst section of the M1 is a stretch of road northbound near J24 at Leicestershire where the average speed is just 37.1mph.

On the M11 the slowest part is the southbound carriageway between J5 and J4 in north-east London, heading towards the M25, where speeds average just 42.1mph.

The M62’s slowest section is the westbound carriageway between J19 and J18, near Manchester, where average speeds are 44.6mph, while the M6’s worst stretch is southbound between J10 and J9, where the average is 41.7mph.

Rod Dennis, of the RAC, said: ‘As these figures show, drivers will be lucky if they can drive anywhere approaching the national speed limit on some of England’s most congested stretches of motorway.

‘While some are notorious and seemingly permanent bottlenecks, others are likely to be caused by long-term roadworks which means drivers will have to hope that journey times will drop when they’re finally lifted. 

Second slowest is a northbound stretch of the M5 (pictured) at junction 2, near Birmingham, where drivers endure average speeds of 26.7mph

‘Drivers tell us that they are becomingly increasingly dependent on using their cars, so it’s vital that investment in our motorway network is maintained.

‘Worryingly for drivers, we have seen evidence that some work to reduce traffic at pinchpoints on the motorway network has actually had the undesired effect of making congestion even worse, not better.

‘Clearly, tackling congestion on the UK’s major roads is never a quick or straightforward task, or for that matter, cheap.’ Across Britain, motorists spent an average of 178 hours stuck in traffic last year – rising to 227, or the equivalent of more than nine days, in London, according to transport data experts Inrix.

A report earlier this year found that congestion cost the economy £8 billion in 2018 as drivers wasted time sitting in their cars rather than working or spending money in shops and restaurants.

The DfT said it was unable to comment due to the ‘purdah’ period ahead of the General Election.