20 mph speed limits and zones

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Introduction

The first three 20 mph speed limits forming zones were implemented in Sheffield, Kingston upon Thames and Norwich, in January 1991. Since then, around 450 zones have been installed in the UK. Until June 1999 specific consent from the Secretary of State was needed. The legislation has now been changed, and local traffic authorities no longer need to obtain the consent of the Secretary of State before implementing 20 mph speed limits.

In addition to changes in the Road Traffic Regulation Act 1984, amendments have been made to the Traffic Signs Regulations and General Directions (TSRGD), the Highway (Road Humps) Regulations, and the Highway (Traffic Calming) Regulations; and the Road Humps (Scotland) Regulations and the Roads (Traffic Calming) (Scotland) Regulations. These make possible two different means of implementing 20 mph speed limits. Broadly, these are:

  • use of speed limits, indicated by terminal and repeater signs alone;
  • a zonal approach using terminal signs together with suitable traffic calming measures to provide a self enforcing element.

The purpose of this leaflet is to provide advice on how and where to implement 20 mph speed limits and 20 mph zones, to help in meeting the objectives of the Government White Paper, "A New Deal for Transport: Better for Everyone" and the requirements for Local Transport Plans.

Example of 20 mph zone signage, Tinsley

Example of 20 mph zone signage, Tinsley

Example of 20 mph zone signage, The Groves

Example of 20 mph zone signage, The Groves

Example of 20 mph zone signage, North Earlham

Example of 20 mph zone signage, North Earlham

Background

The use of 20 mph speed limit zones was intended to address the serious problem of child pedestrian accidents occurring in and around residential areas, and so was initially limited to these areas. Subsequent research has shown that the risk of a child being involved in an accident has reduced by about two-thirds where 20 mph zones have been installed.

20 mph zones are no longer confined to residential areas. There are a number of town centre zones. In the "Bypass Demonstration Project", four of the six towns had 20 mph zones in their central areas. A small number of 20 mph zones have also been used in rural areas, an example being in Epping Forest.

Bypass Demonstration Project logo

Bypass Demonstration Project logo

Epping Forest 20 mph zone

Epping Forest 20 mph zone

Application

It will be for local authorities to determine whether speed limits or zones should be used. They will need to decide whether the proposed type of speed limit is

  • appropriate to the area, and
  • beneficial in road safety and environmental terms.

Equally important is that the form of speed limit chosen does not require unreasonable levels of enforcement by the police.

20 mph speed limits by signs alone would be most appropriate where 85th percentile speeds are already low and further traffic calming measures are not needed. 20 mph zones should be used where excessive speeds occur, and where traffic calming measures would be needed to ensure speeds are at or below 20 mph. 20 mph zones would be particularly appropriate where there is an existing record of accidents to children occurring over an area, or where concentrations of pedestrians and/or cyclists exist or are anticipated. They can help to protect children walking and cycling to and from school, and may encourage other children to walk or cycle.

With new road layouts, where suitable features can be included in the design, the preference should be for 20 mph zones. Design Bulletin 32 and the companion guide "Places, Streets & Movement" provide further advice.

Places, Streets & Movement companion guide

Places, Streets & Movement companion guide

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