20 mph limits

20mph zones, areas and limits have been gaining in popularity in recent years but their overall impact on road safety is at best unclear.

Schemes to reduce speed through communities are often popular with local residents but their biggest benefits are often in health and environmental improvements rather than injury reduction. Speed limits must match the road environment or drivers can become confused so getting the speed limit right promotes self-compliance and removes the need for expensive enforcement.

IAM RoadSmart recommendations

• IAM RoadSmart do not favour a blanket approach to speed limits or a wholesale change in the urban limit from 30 to 20
• Distributor roads should always remain as 30mph or above with segregated design features for enhanced pedestrian and cycling safety.
• The key requirement of any 20mph zone must be that it is self enforcing through signposting that makes sense or traffic calming features
• IAM RoadSmart do not support the use of speed cameras in 20mph areas but would like to see a specific retraining option available for those caught breaking the limit
• Given the low number of injuries on residential roads limited police enforcement resources must be prioritised elsewhere
• IAM RoadSmart has no wish to deny anyone the opportunity to live in a better environment with limited traffic intrusion and we would not object to 20mph limits across housing estates where average speeds are already below 30mph
• More research is needed on the long term safety performance of different approaches eg mandatory limits versus advisory, traffic calming versus sign only
• Research suggests that drivers use the clues from the environment around them to judge the correct speed. Where limits do not match the environment uncertainty and confusion are generated which can raise stress levels and provide an unwelcome distraction from safe driving and lead to a wider disrespect for limits.
• IAM RoadSmart has no objection to the relaxation of traffic order requirements to make schemes easier to implement
• Local consultation is crucial to ensure that those people who live on and use the affected roads fully understand what to expect
• Detailed design and high quality materials in traffic calming features and signposting are a basic requirement in all schemes
• Schemes must not be promoted on purely road safety grounds but in an open and honest way that shows the wider benefits to the local population.