Advanced traffic data analysis from INRIX has confirmed the worst time for congestion in Devon. Analysis of millions of historical data points has revealed a consistent and recurring M5 southbound bottleneck between Junction 27 and Junction 31, uncovering a specific Friday afternoon travel trap that adds up to 50 minutes to journey times; while National Highways maintains that overall Devon congestion remains steady, this new INRIX traffic data exposes the true scale of the August holiday gridlock facing motorists heading into the South West, says North Devon Today.

Bryn Mills, VP of Engineering at INRIX, said:

“Friday late afternoon stands out as the clearest recurring pressure point for traffic heading into Devon. The data also suggests that Fridays in August are noticeably worse than a typical Friday, with journey times on the southbound route significantly above normal free-flow conditions during the afternoon peak, with delays of up to 50 minutes compared to other times of the year.”

Mr Mills added that the worst individual days in INRIX’s dataset tend to cluster around summer holiday periods, autumn Friday peaks, and Christmas getaway dates, reinforcing the view that holiday traffic is the primary driver of delays on this stretch of motorway.

INRIX’s year-over-year analysis suggests these patterns have remained relatively stable in recent years, though Mr Mills flagged one potential pressure point for the summer ahead.

“It will be interesting to see how any increase in ‘staycationing’ this summer due to world events plays out in delay data this August,” he added.

National Highways said that across the 10 busiest days on the M5 between junctions 29 and 30 in 2025, the motorway carried roughly 60,000 to 70,000 vehicles per day in each direction. 

The busiest days last year, measured by vehicle numbers, were the Fridays between June and August, along with the two May bank holidays.

(Picture: Mapillary)