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20mph speed limit

We have now completed the first two phases of a four year project to implement maximum 20mph speed control across most residential and shopping streets in Cambridge.  The third and final phase, covering West Central and South areas, of the project has now reached implementation stage.

This follows an extensive city-wide consultation exercise were the majority of respondents were found to be supportive of 20mph speed control.

The overall public response to all of the consultations was in the region of 15%. Overall the consultation results indicate that the majority of responses are in favour of the 20mph limit on residential and shopping roads (71%).

It is intended that the new limits will be enforced using signs and road markings only, without the need for new road humps or any other physical speed management measures.  ‘A’ and ‘B’ roads are generally not included in the plans; we intend to leave these at their existing speed limits.

The scheme has led to a reduction in recorded vehicle speeds since it was introduced.  Of those streets where average traffic speeds were previously above 20mph, some 93% have seen a reduction.

The project, which has an approved budget of £600,000, has been split into three phases, covering different areas of the city. The project map shows which areas each phase covers and highlights the roads that are not covered by the proposal.  20mph control across North area wards was completed in 2014 and across East area wards in winter 2015/16.  The implementation of the original Phases 3 & 4 is now combined to expedite delivery to complete in late 2016.

The maps below show the roads included in the 3rd Phase.

A draft implementation programme for the installation of the final phase 3 work is attached below:

Benefits of the proposal

20mph speed control should help to encourage more people to choose to walk or cycle.

There are many benefits to the introduction of a citywide 20mph speed limit. These include:

  • providing road conditions that encourage and facilitate the take-up of active and sustainable transport modes, such as walking and cycling, with associated health and wellbeing benefits
  • making it easier for pedestrians to cross roads, particularly for children or the elderly
  • reducing the amount of road noise generated in residential areas
  • improving traffic flow, as it flows more smoothly through junctions at lower speeds
  • potentially reducing airborne pollution levels

The severity of injuries sustained as a result of road accidents can also be reduced when traffic travels slower. According to ROSPA, a pedestrian struck at 20mph has a 97% chance of survival; this falls to 80% at 30mph and 50% at 35mph.

Monitoring of traffic speeds both before and after the introduction of the 20mph control in north area wards showed that, on average, speeds reduced by 1-2mph; which was consistent with Department of Transport advice and the expectation of the Cambridge project.

20mph project seminar presentations

A 20mph project seminar has taken place which covered a number of issues associated with 20mph speed limits in general, and in relation to the Cambridge proposals. The following presentations were given:

Case studies

Large-scale 20mph projects have recently been completed or are currently being progressed in a number of other cities. These include Bath, Edinburgh, Liverpool, Oxford and York.

The introduction of a 20mph speed limit in Bristol has resulted in an increase in levels of walking and cycling and no negative impact on bus journey times, while monitoring suggests the introduction of a 20mph speed limit in Newcastle has reduced the number of road accidents.

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