Speed limits in urban areas should apply in street that are primarily residential and in order town or city streets where pedestrians and cyclist movement are high, such as around schools, shops, market, university and movement is not the primary function, in this case the speed limit including 20 mph zone. In other built-up areas where motor vehicle movement is deemed more important, with development on both sides of the road which is the speed limit including 30 mph zone.

Speed limits are set generally to balance road traffic safety concerns with the effect on travel time and mobility. Speed limits are also sometimes used to reduce death, consumption of fuel or in response to environmental concerns.
A road speed limit is the limit of speed allowed by law for road vehicles, usually the maximum speed allowed. Speed limits are usually set by the legislative bodies of national or local governments. Speeds are listed in kilometers per hour. The United Kingdom and the United States, the speed limit is also listed in miles per hour in brackets. Germany, with its Autobahns, is the only country without a general speed limit on its highways.
The highest posted speed limit in the world is 140 km/h (87 mph). Best known are Germany 's less congested Autobahns, where automobile drivers have no mandated maximum speed. Speed limits may also be set in an attempt to reduce the environmental impact of road traffic (vehicle noise, vibration, emissions) and to satisfy local community