Road Narrowing

Road narrowing simply reduces the width of the road. This could be achieved in a number of ways, however the technique normally used in Bristol involves extending the curb at a junction entrance with a bollard on each side.

Motorists will need to drive more carefully in a narrowed section of road to keep their vehicle in the correct road position, which may result in slower vehicle speeds.

In addition, road narrowing can also be used to help pedestrians cross the road more easily. In this case, the kerb is dropped with tactile paving where the pavement slopes towards the road.


  • Not as effective as vertical treatments
  • Managing water drainage could be complex and costly
  • Cyclists may feel intimidated by some vehicle drivers' behaviour at road narrowing


  • Road narrowing should not be used on roads or junctions with any heavy goods vehicle traffic

There's also some general restrictions to note for all schemes

Cost:   £6,000 - £12,000


  • Targets a specific part of the road
  • Can be used on junctions
  • Can prevent vehicle parking
  • Make it easier for pedestrians to cross
  • Emergency vehicles should be able to pass without slowing down
Road narrowing with 20mph


Generally, horizontal treatments - such as road narrowing - are expected to reduce accidents by around 29%.

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29% reduction in accidents is taken from Mountain, Hirst and Maher (2005). The study calculated accident reductions from various different types of traffic calming measures. Local authority and police data were used throughout Great Britain from 150 speed management schemes on 20 mph roads. Analysis is particularly strong, with correction for change in flow, accident trend and regression to mean.


Mountain, L., Hirst, W., Maher, M. (2005) Are speed enforcement cameras more effective than other speed management measures? The impact of speed management schemes on 30 mph roads. Accident analysis and prevention 37 pp. 742 - 754.

Also Consider:
Speed Cushions
A speed cushion is a short, raised, rounded device, normally in the centre of a road lane. Speed cushions are designed to be slightly wider than a car, so car drivers need to slow down and drive over the centre of the speed cushion to reduce discomfort.
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Single lane chicanes require one direction of traffic to give way to oncoming vehicles. The chicane normally consists of a raised curb and bollard in one half of the road, with a sign to explain the traffic priority.
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Speed Table
Speed tables are a raised section of road, with a ramp on both sides. The ramps are painted with white arrows to make them more obvious to vehicle drivers.
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Speed Cameras
Speed cameras photograph vehicles which are travelling over a certain speed. This is usually around 10% over the speed limit. Speed cameras use a radar device to detect the speed of passing vehicles.
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Speed Humps
Speed humps have a short rounded top which is typically 75mm high. The ramps either side are painted with white arrows to make them more obvious to vehicle drivers.
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Vehicle-activated Signs (VAS)
VASs are an electronic sign which only become visible when approaching vehicles are exceeding a certain speed.
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Pedestrian Refuge Island
A refuge island is a raised section of pavement between two lanes of traffic moving in opposite directions. The Islands normally have yellow and white plastic bollards with a blue arrow to remind drivers to keep left.
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DIY Streets
DIY Streets
DIY Streets is a concept developed by Sustrans which encourages communities to generate ideas for the improvement of their street. The concept aims to make the street less car dominated, and more community focussed.
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Community Speed Watch
Community Speed Watch
Community Speed Watch is a scheme to allow volunteers to monitor the speed of passing vehicles using a hand-held speed detection device.
Read more > >
Change Lane Markings
Change lane markings
Peripheral hatching or removing the centre line can reduce the feeling of space motor vehicles have, which may help to reduce their speeds.
Read more > >