Measures to control the speed of traffic include speed limits, road humps and traffic calming. 
Speed Limits
Research has shown that speed is a major contributory factor in around one third of all road accidents. The Scottish Government is, therefore, keen to cut the speed of vehicles, particularly near schools and in residential areas.
The national speed limits are:
- 30 mph on roads in urban areas
- 60 mph on single carriageway rural roads
- 70 mph on dual carriageways and motorways
The Government can set lower speed limits on sections of trunk road, while local authorities can set lower speed limits on local roads.
The Government issues guidance to local authorities on setting appropriate speed limits.
Revised guidance for traffic authorities on setting local speed limits was issued on August 9, 2006.
20 mph speed limits
Twenty mile per hour speed limits can increase safety for pedestrians, children and cyclists in residential areas, shopping areas and near schools.
They can be mandatory or advisory, operate at all times or at certain times of day, and can have associated road humps or traffic calming features.
Guidance for local authorities on 20 mph speed limits is provided by:
Traffic calming and road humps
Local authorities have the power to construct traffic calming measures to reduce the speed of traffic. The range of measures available includes -
- Chicanes
- Build-outs
- Pinch-points
- Gateways
- Rumble devices
- Islands
- Road markings
- Road humps of various design
- Speed cushions
- Raised junctions
- Speed tables
Traffic calming and road humps can be used alone or in association with a reduced speed limit.
The Government provides guidance to local authorities on the use of traffic calming and road humps.