Speed limits are the most important means to send out a message to road users about the type of road and the mix of road users to expect to share with. Lower speed limits have been proven to reduce the frequency and severity of crashes, as well as air and noise pollution. They can also be crucial in encouraging people to feel safe walking or cycling more.
This section isn’t just about reducing speed limits, it is also about more careful planning of speed limits. Sometimes speed limit changes appear to be arbitrary - the 30 mph limit starting by fields a long way from a village or a 20 mph stopping in the middle of a housing estate. Such changes can be confusing and discredit the system.
The starting point is the national or default speed limit which vary on the type of vehicle and road. For cars these are:
- 30 mph where there is a system of street lights, typically in built up areas
- 60 mph (though lower for most vans and larger, commercial vehicles) on single carriageway roads outside built up areas, typically in the countryside
- 70 mph (again lower for larger vehicles) on dual carriageways, those roads with a physical barrier in the middle - these are generally strategic trunk roads so outside the scope of the toolkit.
More information on speed limits is available on GOV.UK.
Local speed limits are implemented by the highway authority through a legal process known as a traffic order, backed up by speed limit signs. 20 mph is increasingly the norm on streets in residential areas and town centres, while 50 mph is common on busier roads in rural areas. Normally local speed limits require repeater signs to remind drivers of the lower speed limit. 'Zones' are areas where there is a lower speed limit - typically 20 mph, though in some national parks there are 40 mph zones - signed at gateways but then without the same requirement for repeater signs.
Speed limit changes work best when they are planned systematically across road networks and in an integrated way that combines education and enforcement. The shaping routes and networks plus the tackling speeding section for more information and ideas. Speed limits should fit with the road environment so that drivers tend to comply them because they feel right for the road environment. This should not mean simply setting the speed limit to the majority speed but may mean needing to adapt the road environment to encourage compliance. Using natural features, such as hedges or adding planters to narrow the road, and removing artificial features, such as lines can help, particularly for lower speed limits.