Civilising our streets via a borough-wide 20mph speed limit

Moving towards safe, attractive, enjoyable and sustainable streets in Wandsworth via a borough-wide 20mph speed limit

This note is based on a Wandsworth Friends of the Earth briefing prepared for Wandsworth Council as part of WFoE’s ‘Get Serious about CO2’ campaign, which focuses on the environmental and social problems caused by excessive dependence on motor vehicles for local transport and suggests some ways to improve the current situation.

The dominance of motor vehicles, and associated fear of road traffic, deters many people from considering transport modes – particularly walking and cycling – which form part of the solution to many environmental, social, and health concerns.

An area-wide 20mph speed limit represents the quickest and best value for money approach to encouraging sustainable transport in our borough, following Portsmouth’s lead, and has been described as a real sign of a civic society.

Benefits of lower speeds

Some of the benefits that could be expected from slower traffic speeds in Wandsworth achievable by reducing the ‘default’ speed limit from 30mph to 20mph include:

  • Reduced deaths and injuries: There is overwhelming evidence that the incidence of death and serious injury from road traffic is massively reduced as speeds are reduced. Preliminary work by Transport for London in 2003 attempted to quantify the savings of introducing more widespread 20mph zones.  More recently, Grundy et al.’s British Medical Journal paper (see Annex) provides compelling evidence of the effects of 20mph zones in London in terms of reduced death and injury on our roads.
  • More people walking and cycling: A lower speed limit would make our streets less noisy, less dangerous for cyclists and pedestrians, and as some drivers switched away from car use for short journeys, less polluted. In other words, our streets would become more people-friendly. This would encourage people to use our streets on foot, for example when doing short shopping trips. And more people would also start using bicycles as they felt the streets were safer and more pleasant to cycle on.  Achieving a modal shift in how people move around our borough would therefore be supported and facilitated.
  • More children walking and cycling regularly: As traffic becomes less threatening, and the streets more inhabited by recognisable individuals, parents begin to feel more comfortable with their children walking or cycling to school and to meet friends. This has many benefits for local children and their families – improving children’s physical fitness, reducing obesity, enhancing children’s mobility and independence in preparation for adulthood, and improving children’s health and wellbeing generally.
  • Less street crime: As more people use the streets, natural surveillance comes into play, reducing opportunities for crime and making our streets safer, and perceived as safer.
  • Less congestion: As people in our borough felt comfortable about making more journeys on foot or by bicycle, the number of private motor vehicles on local roads would fall, thus contributing to reduced congestion.  Reduced car use (together with supporting measures such as car clubs) will also result in less pressure on scarce highway space, facilitating the return of Wandsworth footways to pedestrians.
  • Enhanced mobility for older people: With safer, quieter streets, older people would feel it was possible to get out more to visit friends and neighbours, walk to parks, do local shopping on foot etc. This would enhance their quality of life, as well as bringing health benefits and supporting the local economy.
  • Quieter, healthier, more pleasant residential neighbourhoods: This would be another result of fewer and slower motor vehicles on our streets.  It would directly support the return of ‘the public’ to the major part of Wandsworth’s public realm.
  • Reduced CO2 emissions; and so less damage to the climate: The Department for Transport accepts that cars driven at slower speeds emit less CO2 . This fact, together with a reduction in the volume of motor traffic on our roads, as people choose to walk or cycle more, would help to lower the borough’s climate-damaging, greenhouse gas emissions.

Is a borough-wide default speed limit of 20mph practicable? The Portsmouth Success

The City of Portsmouth (population: 197,700) in March 2008 introduced a city-wide 20mph speed limit, demonstrating that local leadership combined with community engagement can make a difference in how local citizens think about their streets.  The success of Portsmouth’s scheme, introduced at a cost of only £570,000, has taken the Department for Transport by surprise, contributing to recently revised draft guidance – which opens the doors to other local authorities wishing to adopt a progressive policy for their own public realm.

One comment on Portsmouth makes a key point about the feasibility of this measure:

What really stands out from the Portsmouth 20 mph success is that it confounded the experienced traffic managers. Hitherto it had been said that with signage alone only a 1 mph reduction in speed limit would be achieved…. The streets in Portsmouth which the DfT suggested would be least likely to reduce their speed (those previously above 24 mph) in fact had a whopping 7 mph reduction. What was also noticeable was the reduction in speeds on 30 mph roads and also the lower “pace” of traffic when accelerating from lights or junctions.

This was not because of the signs or the enforcement, but because the council provided a framework for social change. It enabled the good citizens of Portsmouth to discuss and decide what they wanted and then put into place a speed limit regime which enabled them to say that ‘20’s Plenty’ where people live. (From: ‘Letter to the Parish Council’, 9 October 2009, )


Support WEF’s Call on Wandsworth Council to introduce a ‘Default’ 20mph speed limit on all borough-controlled roads in Wandsworth.

In urban areas only the busiest strategic traffic routes should now qualify for higher speed limits.

(‘Take action on active travel: Why a shift from car-dominated transport policy would benefit public health’, Association of Directors of Public Health, January 2010, p. 3).

This in effect means a fundamental change in the rules governing our streets.  The current 30mph ‘default’ in built-up areas replaced no speed limit at all when introduced in 1934 – a time when motor traffic volumes were an order of magnitude less than now. There would be a presumption of a 20mph speed limit throughout the borough for Wandsworth Council-controlled roads.  For busy roads, such as Wandsworth’s Strategic Road Network, the Council may choose to make the case to the community for the road not to have a 20mph speed limit. This case-by-case approach would reverse the current 20mph zone procedure whereby, for every road where local residents wish a 20 mph limit, expensive and time-consuming consultation procedures and infrastructure changes have to take place.

John Horrocks & Jonathan Callaway (Convenor), Transport Panel,  

The Putney Society

Susie Morrow,  

Campaigns Coordinator,

Wandsworth Cycling Campaign

April, 201

Annex: Useful resources on 20mph speed limits