The proportion of cars exceeding the speed limit in free-flowing conditions has remained broadly stable since 2011, the DfT has concluded, after publishing new data for 2019.
The statistics measure speed and compliance at sites where the road conditions are ‘free flowing’ – for example roads with no junctions, hills, sharp bends, speed enforcement cameras or other traffic calming measures.
In 2019, approximately half of cars were found to be exceeding the speed limits on motorways (50%) and 30mph roads (54%). At 9%, the figure was much lower on national speed limit (NSL) single carriageways.
Looking at more extreme incidents of speeding, the proportion of cars exceeding the speed limit by more than 10mph was 12% on motorways, 6% on 30mph roads and 1% on 60mph roads.
The DfT says the statistics provide insights into speeds at which drivers choose to travel when free to do so, but are not estimates of average speeds across the whole network.
It notes that the average car speeds under free flow conditions were close to the speed limit on motorways (69mph) and 30mph roads (31mph) – and under the speed limit on 60mph roads (50mph).
Majority continue to exceed 20mph limits – but extra caution needed
The figures also show that 86% of cars exceeded the speed limit on roads with a 20mph limit – with 20% breaking the limit by more than 10mph.
While these figures may seem alarming, the DfT stresses that free flowing conditions are not typical of most 20mph roads and as a result, must be ‘interpreted with additional caution’.
DfT guidance suggests that 20mph limits are most effective when they have traffic calming measures or when average vehicle speeds are already below 24mph.