The motorway speed limit – 70, 80 or ?

Policy issued on 15/02/16 |
Motorway Speed Limit

Motorways are our safest roads because they are designed for high speeds and the vehicles using them today have also never been safer.

Speed surveys show that on uncongested motorways, 57 per cent of car drivers exceed the 70mph speed limit, and 20 per cent exceed 80 mph. IAM RoadSmart’s most serious concern is that legalising today’s unofficial and tolerated 80 mph speed limit could create tomorrow’s unofficial 90 mph limit. Average traffic speeds would increase, as would accidents and their severity and more people could be killed and seriously injured.


Not all UK motorways are built to the highest standards and many have sections with limited sight lines, tight curves, only two lanes and slip road designs that may not be able to deal with a higher limit safely.

Closely monitored smart motorways which set the speed limit according to traffic flows and density do however offer the ability to increase limits and enforce them. If the speed limit can be lowered below 70 mph in congested conditions, it could just as easily be increased to 80 mph when traffic flows are much lighter and conditions are good.

In Holland the limit was recently increased to 80mph (120kph) after a comprehensive review of motorway capacity, congestion and safety. The limit has only been increased on those sections where the road can cope with it. The vast majority of the busy Dutch motorway network remained unchanged or had variable limits applied to recognise varying traffic conditions throughout the day.

British motorways are the most congested in Europe so few drivers actually achieve 70 mph consistently on every journey. Any change in the limit is therefore unlikely to affect most drivers on their daily commute.

IAM RoadSmart recommendations

  • The Department of Transport should announce once and for all if it is even considering raising the motorway speed limit
  • Technical work should begin on the feasibility of raising the limit to 80mph on existing and future smart motorways
  • Trunk road agencies across the UK should carry out comprehensive reviews of their motorway network to identify those sections that could safely accept a higher limit and those that could not
  • Highways England, Transport Scotland and The Welsh Assembly should bring forward proposals for an 80 mph speed limit pilot to assess safety, practicality and driver acceptance.