51% of Car Drivers Speed in 30mph Zones

51% of car drivers speed in 30mph zones under free-flowing traffic conditions, according to vehicle speed compliance statistics published by the DfT in June 2022.

These figures provide an insight into the speeds drivers travel at when free to do so, with the locations chosen excluding external factors like sharp bends and speed cameras.

On motorways, 48% of car drivers exceed the speed limit. However, compliance with the speed limit on single carriageway A-roads is much better, with just 11% of drivers breaking it.

Average Speeds

Average car speeds under free-flow conditions were much closer to the speed limit. They were:

• 31mph on 30mph roads
• 51mph on 60mph roads and
• 69mph on (70mph) motorways

Distribution of Car Speeds by Road Type 2021

The proportion of car drivers exceeding the speed limit by over 10mph was:

• 5% on 30mph roads
• 1% on 60mph roads and
• 10% on motorways

HGVs on Motorways

98% of HGVs complied with the speed limit on motorways, and that is attributed to compulsory speed limiters. Vehicles over 3.5 tonnes are limited to a maximum of 56mph.

This shows that a system of speed limiters on all vehicles would be effective.

More Speeding at Weekends

Speeding increased by a small but significant amount at weekends compared with week days.

For example, on 30mph roads the percentage of car drivers speeding was:

• 50% on week days and
• 55% at weekends

20mph Roads

The 20mph free-flow sites tend to be unrepresentative of 20mph roads in general, with a lower proportion of residential streets.

The DfT report notes that:

• 20mph limits are supported by the majority of drivers and residents
• introducing a 20mph limit reduces drivers’ speeds, even though not often to 20mph

87% of car drivers exceed 20mph speed limits, and 19% exceed the limit by more than 10mph.

Reasons Given for Breaking the Speed Limit

The reasons given for speeding come from the RAC Report on Motoring 2021.

‘I drive according to the speed of other road users’ and ‘feel pressure from other drivers behind’ are two significant reasons given.