9 Jul 2010

20: Why we need it

Below is my 10 page report '20mph: Why we need it' which was hurriedly thrown together in response to the news that councillors at the County will be discussing this issue on Wednesday. I also sent a covering letter which I will post on this blog on that Wednesday morning ahead of the meeting. You will need to increase the font size to read but wanted to publish it all here so folk can see the arguments which have been made many times on this blog - I can send a pdf if you email me - sadly below doesn't include the photos of the original.

20: Why we need it

By Cllr Philip Booth, Stroud District councillor for Randwick, Whiteshill and Ruscombe ward. These notes were adapted from the Living Streets ’20 mph Policy Briefing’ to support Parish Councils request for 20 mph across the whole ward. 10th July 2010


Streets are where we live, play, work, and socialise – they should be safe, attractive and enjoyable places for everyone. The current default speed limit for built up areas is 30 mph. Yet half of drivers admit to regularly “driving significantly above” the current 30 mph speed limit in built-up areas (1).

20 mph makes sense. The road safety statistics speak for themselves. If you are struck by a passing car in your street at 35 mph there is a 50% chance that you will be killed (2). This is a shocking fatality rate, which has an impact not just on those involved in collisions, but creates a wider fear of traffic speed that in turn adversely affects how we use our streets. At a traffic speed of 20 mph, the pedestrian survival rate is immediately increased to 97% (3).
This paper looks at 20 mph and how it cuts casualties along with the other benefits like increase walking and cycling. It considers why 20 mph zones are a less good way to go and notes issues of costs and enforcement with the example of Portsmouth who have a citywide 20 mph.

The framework is in place across the UK for local authorities to implement 20 mph local limits cheaply and easily. With an expected constraint on finances in the future then “value for money” of any intervention will be a key consideration. As the “Total 20” approach with speed limits costs 51 times less than 20 mph zones, then for any given expenditure a “Total 20” approach will deliver far wider benefits to residents. For the same expense as engineering a 20 mph zone for 250 houses and 500 people then over 25,000 could benefit from a 20 mph speed limit in their road.

Benefits from a Total 20 scheme would be :-

· Demonstrates Council commitment to making streets safer and improving quality of life
· Reduces Road Danger for all road users
· Encourages a shift to walking and cycling
· Reduces emissions
· Increases mobility for children with consequent gains in health and self-esteem.
· Increases inclusion and access for those without motor vehicles.
· Reduces noise.
· Reduces congestion due to “School run” motor vehicles.
· Increase social cohesion.
· Consistently sets speed limits
· Creates a commitment to sharing the roads more equitably.
This paper includes: 1. Cut casualties. 2.Encouraging more walking and cycling. 3. Improving Sociability. 4. Positive impact on emissions and traffic flow. 5. 20 mph is in line with existing County Council policy. 6. Limits vs. zones. 7. Making 20 mph a reality. 8. Portsmouth Case Study: achieving 20 mph the logical way. 9. Brief history of traffic calming in Whiteshill and Ruscombe Parish. 10. Notes
1. Cut casualties

Reducing motor traffic speeds on our streets is the single biggest measure which will make them safe and vibrant places.

1.1. Chances of death or serious injury are dramatically reduced when speeds are reduced from 30mph to 20mph. While good progress has been made on reducing road casualties across the UK, no one should be satisfied when the equivalent of 60 classrooms full of children were seriously injured or killed on our roads last year.

1.2. There are stark road safety benefits with a 20 mph limit. Firstly, a pedestrian struck at 20 mph has a 97% chance of survival. At 30 mph the figure is 80%, falling to 50% at 35 mph 10. Children are the most vulnerable type of pedestrian, and they stand to benefit greatly from lowering the limit to 20 mph. This has been shown to reduce child pedestrian deaths by 70% (see figure 3.3 from WHO report above) (4).

1.3. World Health Organisation (2004) World report on road traffic injury prevention. Chapter 3, page 9 notes: “The speed of motor vehicles is at the core of the road injury problem. Speed influences both crash risk and crash consequence.”

1.4. Hull City Council has introduced 20 mph zones on a quarter of its roads. Figures comparing the three years before the speed limit was changed with the three after show there has been a 74% reduction in the number of crashes involving child pedestrians, and a 69% reduction in child cyclist crashes. The overall number of collisions in Hull has been reduced by 56%, and there has been a 90% reduction in serious or fatal injury collisions (5).

2. Encourages more walking and cycling

2.1. Better atmosphere: 20 mph helps create an environment in which pedestrians feel confident about crossing the road, children can play outside their homes and it is quiet enough to hold a conversation. A study from the Commission for Integrated Transport in 2001 found that where cities have 20 mph speed limits covering between 65% and 85% of the street network, they are transformed “from being noisy, polluted places into vibrant, people-centred environments.” (6)

2.2. Walking and cycling increased: A 20 mph speed limit in built-up areas allows for the safe mixing of motorised and non- motorised modes of transport, and makes it easier for pedestrians and cyclists to enjoy the same direct and safe routes for their journeys as motorists. Research into traffic calming undertaken in Glasgow found that walking levels increased in traffic-calmed neighbourhoods (7). It is worth noting there are huge health benefits to more walking and cycling.

2.3. Best practice: As Atkins report on integrated transport schemes: “The one critical success factor underpinning best practice in all case study areas was the introduction of area wide 20 mph zones (8).”

In Europe there is also evidence that lower speed limits encourage walking and cycling. The 20 mph approach is increasingly adopted in European countries where rates of walking and cycling are much higher and casualty rates for sustainable road users much lower than in the UK (9).

The use of 30 kph (19 mph) speed limits for roads in residential, shopping and other "mixed use" areas is nearly universal in Germany. In Hilden, a town of 50,000 people near Dusseldorf, a 30 kph speed limit was introduced over most of the road network to improve safety and quality of life and to avoid the expense of providing a comprehensive network of cycle lanes. 60% of trips to the town centre are now made on foot or by bicycle (10).

In Munich, with a "pedestrian friendly city" policy, 80% of the road network has a 30 kph limit. Some residential areas have even lower limits. In Graz, Austria, over 80% of the network has 30 kph limits. Cycle usage increased by 17% while cycling casualties fell. Munich also has very low casualty rates for vulnerable road users. Munich exemplify best practice because they have stabilised or reduced the use of the car, despite increasing levels of car ownership (11).

Photo: Whiteshill School children being escorted along road

2.4. Impact of increased traffic: The 30 mph speed limit was introduced in 1934 when there were just 2 million cars in the UK. Today there are over 28 million. There is now roughly one car for every two people in the UK. From a ‘crossing the road’ point of view, 30 mph was a far more appropriate speed in the 1930s than it is today. The relative rarity of a car on the street meant that crossing it in good time before one appeared was a simple matter. With today’s increased car use, sufficient gaps in 30 mph traffic are much harder to come by. We’ve almost taken it for granted that stepping out onto the street is a risky business: something to be rushed, fearful for our safety. A 20 mph speed limit immediately puts people first by ensuring that traffic is travelling at a speed slow enough to adapt to pedestrian presence.

3. Improving Sociability

3.1. Heavy traffic damages communities – and the speed of traffic plays as great a role as its density. Research from Basel in Switzerland has shown that the sociability of streets increases as street traffic speeds decrease. For example, the number of people saying they ‘linger’ in their street increases from 24% in a 50 kph (31 mph) street to 37% in a 30 kph (19 mph) street (12). Meanwhile, research from Bristol in the UK has shown that residents on busy streets have less than a quarter of the local friends that those living on similar streets with little traffic have (13). At 20 mph, even a heavily-trafficked street instantly becomes easier to cross, less noisy, and more sociable.

3.2. The Institute of Public Policy Research’s report Streets Ahead confirms the link between poverty and children’s road safety: it shows that children in the poorest 10 per cent of society are three times as likely as children from the richest 10 per cent of society to be pedestrian casualties. Overall, child pedestrian injuries are four times as likely in poorer area, than in richer areas. All of the wards in Hull are amongst the third most deprived in the country and this has been a strong incentive in reducing speeds in the city.
4. Positive impact on emissions and traffic flow

There are wider benefits of 20 mph. Contrary to some reports based on test-track conditions, research, again in Germany, showed that driving at a steady 30 kph (19 mph) will actually reduce vehicle emissions as braking and accelerating between junctions and other obstacles decreases(14). It is very much an environmentally friendly traffic speed.

Additionally, traffic flow is smoothed by reducing the “bunching” effect at junctions. Some local authorities have already pioneered this approach to traffic management. The London Borough of Camden has linked the traffic lights on Camden High Street to build in a natural “green wave” of 20 mph: travelling faster than this will simply result in the next set of lights the driver approaches remaining red.

5. 20 mph is in line with existing County Council policy.

The County has many policies that could be partly met by 20 mph:

- The Corporate Strategy has aims of Making our communities safer, Supporting communities and vulnerable people, Ensuring every child thrives and reaches their potential, Making transport work and Managing our environment and economy. A 20 mph in residential areas ticks all these boxes.

- LTP targets (and to a lesser extent GH targets) are to be focused on all the Government’s shared priorities of accessibility, congestion, safety and air quality and the local priorities of maintenance and quality of life (which includes dealing with the impact of freight). A 20 mph would impact positively on all these targets.

- Plus GCC has specific policies re Walk to School, Safer Routes to School, reduce car use, cut carbon emissions, key performance indicators (KPIs) relating to killed and seriously injured levels and much more!

6. Limits vs. zones

Implementing 20 mph does not necessarily entail the use of physical traffic calming which, while effective (15), is costly and can be unpopular. This is where a crucial distinction between zones (requiring traffic calming) and limits (requiring only signage) needs to be emphasised. Living Streets, note the benefits of traffic calming, but argue that a piecemeal zonal approach will be both time consuming and expensive, particularly considering the current economic climate. Additionally, poorly designed traffic calming can cause discomfort to cyclists and bus users.

6.1. 20mph: not just outside schools. Living Streets have concerns about only targeting 20 mph around specific streets. While this can be a welcome first step, 20 mph is the only civilised speed for all streets where people live, work, play or go to school. The onus should be on local authorities to take 20 mph as a starting point for all streets in built-up areas – and demonstrate why a street should not enjoy a 20 mph, rather than why it should. Indeed research in Gloucestershire a few years ago demonstrated casualties don’t occur just outside schools.

6.2. Changing the speed culture: an authority-wide approach across built-up areas would also remove confusion for drivers by avoiding a situation of constantly changing speed limits. This approach would save the expense and clutter of extra signs or engineering. In this way, 20 mph will become the assumed default speed limit across our villages, towns and cities.

Photo: 20 mph zone in Uplands, Stroud where vehicles cannot exceed 15 mph anyway due to narrowness of road: such zones do not make financial sense and add to unnecessary road paint and signage.

6.3. Road designs: Unfortunately, many of our streets built since the 1930s have been engineered for a 30 mph or greater speed limit. For example the radii of side streets are often not harsh enough to deter vehicles from turning in at inappropriate speeds, and carriageways are wide with long uninterrupted sightlines more akin to motorways than places for people. It is no surprise therefore that criticism of 20 mph in such streets focuses on the lowered speed limit not being ‘realistic’ for drivers. So while there is no doubt that the way a street is designed plays a significant role in the speed at which drivers feel is appropriate, wholesale street redesign projects cost millions of pounds and can take years to be realised.

6.4. 20 mph default: Living Streets recommend changing the default speed limit across whole areas, in order to make the quickest and most cost-effective strides towards 20 mph across our villages, towns and cities. DfT plans to strengthen guidance on this although this does still not go far enough.

6.5. Compliance: If, following the introduction of a lower speed limit, there are ongoing concerns about localised compliance, these can be addressed through targeted enforcement or design features (16).

6.6. Displacement: The benefit of a “Total 20” approach is that the only displacement that is possible is from residential roads which may be used as short cuts or “rat runs”. If anything, traffic is displaced onto arterial roads. However, for cyclists and pedestrians then the lower speeds on residential roads make them more attractive than arterial roads. This is a different effect from that produced by local 20 mph zones which may well create displacement to adjacent uncalmed residential roads. If a “Total 20” approach is taken that excludes arterial roads then this will have minimal effect on journey times. As each home is within 1/3 mile of such a road then the maximum increase in time for that 1/3 mile is 20 seconds (the difference in time for 1/3 mile at 20 or 30 mph).
Photo: Gateways at Standish that help slow traffic

6.7. Traffic calming measures: Living Streets note many measures that are cost-effective ways of signifying to drivers that 20 mph is the appropriate speed: removing guardrail and street clutter from the pavement, installing planters on the roadway, removing the centre line and other road markings, and innovative parking bay layouts, to name but a few.

7. Making 20 mph a reality

7.1. The default speed limit for built-up areas should be reduced. In practice this would mean that the assumed speed limit for all streets in built-up areas would be 20 mph: highway authorities would have to demonstrate that there was a clear strategic need for specific streets to have a 30 mph (or greater) speed limit, while ensuring the safety of vulnerable road users.

7.2. Costs: Some Parish Councils are open to considering part payment towards 20 mph zones in their areas. There will also be significant cost savings in reduced casualties and an impact on cutting CO2 and congestion as more people will feel happier to walk and cycle. Living Streets argue that the 20 mph limits approach is cheap and easy to achieve. It is an important first step in stating what constitutes a civilised speed for our streets. If there are concerns about compliance, they can be met via a targeted enforcement approach at specific hotspots following implementation. Local police forces are now saying they will enforce new 20 mph speed limits: Thames Valley Police in Oxford were the latest to state this in April 2009 (17).

7.3. Challenge of Gloucestershire’s priority assessment process: The revised system is based on the ability to obtain measurable benefits in terms of LTP and local targets and our key service KPIs. The total score generated by the system is then divided by the cost to give an indication of priority.

The general principle of the system is that the priority assessment score is as follows

Priority Score = [effect on target] x [number of users] all divided by [cost]

All schemes should be placed into one or more of the LTP categories (see below) and prioritised against a single set of criteria that will take into account all associated GH and LTP > targets.

• Maintenance – subdivided into Bridges, Footways, Drainage, Principal Roads, Non-Principal Roads and Street Lighting
• Quality of Life
• Safety
• Accessibility
• Congestion and Air Quality

This will mean that although a scheme might be focused towards accessibility, it will also be able score additional points for benefits to other targets. I.e. a scheme intended to provide a safer route to school may also have significant benefits in terms of footway condition. In order that the score for any scheme is not unduly influenced by its subsidiary benefits, a factor will be applied to targets relating to its principal purpose. i.e. a maintenance scheme will receive most of its score from maintenance related targets but could gain additional points for cycling benefits.

While this will give a clearer indication of benefits this method looking at schemes individually would appear to not include a change in approach like 20 mph in all residential areas. Changing the culture on our roads could have a huge impact on reducing casualties and carbon.

8. Portsmouth Case Study: achieving 20 mph the logical way

In March 2008 Portsmouth became the first city in Britain to have a 20 mph limit on almost all residential roads – in effect a default speed limit throughout the city, with exceptions for important arterial roads only. The initiative began in a neighbourhood forum, before being taken up by councillors, and finally being put into action by council officers. The entire cost was a mere £500,000. Prior to this, they had been planning to spend £2 million on ten targeted 20mph zones over five years (18).

8.1. Process: To achieve 20 mph, Portsmouth followed Government guidance in Local Transport Note 01/06, Setting Local Speed Limits. The signed-only limits approach, as opposed to costly traffic-calmed zones, became easier in 1999, when the Road Traffic Regulation Act (Amendment) Order 1999 (SI 1999 No. 1608) removed the need for secretary of state approval for 20 mph limits. However it wasn’t until 2006 that Government guidance became positive enough for an authority, in this case Portsmouth, to feel it could take such a bold city-wide step.

Portsmouth City Council felt then that they could only roll out the speed limit on roads where the average speed was already 24 mph or less – even though this is just a “recommendation” in the guidance. It helped that the city is characterised by densely populated, narrow terraced streets, where speeds were naturally low already. According to their own publicity, “The 20 mph limit was proposed for roads where the average speed was already 24 mph or less. We have installed prominent 20 mph signs where drivers enter the new speed restrictions, as well as 'repeater' signs as reminders. It has been found elsewhere that this method reduces speeds by 3-4 mph. Road humps are not part of the scheme, although if speeds do not drop on particular roads, then residents will be consulted again to see if they want additional measures. In most cases the 20 mph limit will be self-enforcing and further speed enforcement measures will not be needed.”(19)

8.2. Enforcement: The police decided to take a targeted, educational approach to enforcing the speed limit. For example in locations where regular violations were taking place, they stopped speeding drivers and gave the option to them of attending a road safety presentation instead of receiving a £60 Fixed Penalty Notice (FPN). According to the police, “Those taking part in the presentations were asked to fill out feedback forms to evaluate their experience, and many agreed that the 20mph zones were a good idea in Portsmouth, and that the information they had seen and heard was of use and would make them drive more responsibly in future.” (20) Nevertheless 50 FPNs for breaking the 20 mph speed limit were issued in Portsmouth from June 2007 to May 20088.

8.3. Results: In the first year it has been shown that whilst the speed of vehicles on roads where previous speeds were low did not drop appreciably, the reduction on roads where previously the average speed was 24-29 mph dropped by 7 mph. There is also the fact that by introducing this across all residential roads in the city the driver ownership and benefit was widely spread and all streets had a consistent speed limit associated with either being primarily residential or an arterial road.

8.4. Conclusion: The Portsmouth case demonstrates how a default limit can be successfully implemented on an authority-wide basis.

9. Brief history of traffic calming in Whiteshill and Ruscombe Parish

The letter below is a copy of the recent letter sent by the Parish Council in response to being informed that they will have to remove their ‘20 is Plenty’ signs. In the eyes of many the ’20 is Plenty’ scheme was only ever seen as a step to try and reduce traffic speeds to make a mandatory 20 mph more acceptable.

Similarly the Parish have sought other measures like Gateways in an effort to reduce speeds. They have even offered payment towards schemes but this has not been accepted. We now await the outcome of this scrutiny meeting.
Photo: ‘20 is Plenty’ stickers on recycling boxes in Whiteshill and Ruscombe.

Date: 21st June 2010

Dear Jo Walker, Director, Highways Transport Services and Waste

Traffic Speed in Whiteshill and Ruscombe,

I understand that Councillor Tony Blackburn will be raising the issue of traffic speed and safe pedestrian access to Whiteshill School at the July meeting of the County Council Environment Scrutiny Committee and thought that some background information may be of use to you. I understand from John Kay, The Gloucester Highways Stakeholder Manager for our parish that you will also be discussing a draft County Policy on the use of 20mph limits which he said he will use to evaluate the application of such a limit to Whiteshill.

Whiteshill and Ruscombe is a ribbon development along what was described by Highways as an "informal route for traffic between Stroud/Cainscross and Gloucester" in their 1998 proposals for traffic calming along the Plain Whiteshill (which has been implemented). The Main Road in Whiteshill was widened in the 1960's in such a way that for most of the village there is only a pavement on one side of the road and this changes whichever side of the road it is on in several places. There is limited section of pavement in Ruscombe. The roads are for the most part a series of bends; this restricts the number of drivers going above 40 mph but historic surveys carried out in 1998 and 2004 and the Parish council in 2003 show that a significant number of motorists exceed the 30 mph limit.

The basic problem as confirmed by Halcrow in their 2004 report on possible sites for School crossings is that there is nowhere in the centre of the village where there is a clear view of the road in both directions to allow a driver travelling at 30 mph to safely stop if there is a pedestrian in the road. Locals know this and have been requesting a 20 mph speed limit since 2000. We have been repeatedly told that for various policy reasons we could not have a general 20 mph limit but that the School area could be an exception and in 2003 (Parish Council Minute 131/08/03) John Lindsay the then Traffic Manager for the area said that Whiteshill School would be added to the list for trial sites for a 20 mph zone. We are still waiting for this to be done!

We were told by our last Stakeholder Manager John Roberts that we could not have a 20 mph limit as the traffic speed was too high and the road too bendy to implement traffic calming. He suggested that we implement a voluntary 20 is plenty scheme as an alternative. We agreed to do this at the Parish Councils expense and after considerable discussion with John Roberts on the designs of the signs implemented the scheme using highway quality signs. The police confirmed that this scheme greatly reduced the number of cars exceeding the 30 mph limit. Unfortunately, John Key is now of the opinion that the signs although made up of components of standard signs do not conform to the regulation for road signs and has had them removed. He says that he will consider the case for a 20 mph zone for Whiteshill once the County has a confirmed policy for their introduction. However a scheme will need to be drawn up and any work will have to be assessed for cost effectiveness. This is worrying as we already know that additional traffic calming cannot be implemented and as we fortunately have a low incidence of major accidents a simple cost benefit analysis will not be convincing.

This approach overlooks the fact that people use their common sense and don't allow their children to walk to school, the playing field, the village shop, the village hall or the Scout hut and end up driving them around the village as it is not safe to cross the road. I understand John Kay’s position and it would be appropriate if there was not the history of past reports. We do not need more expensive studies to tell us what we already know. The evidence from the 20 is plenty scheme is that a mandatory 20 mph limit will reduce the traffic speed.

All the Parish Council is asking for is permission from Highways for us to change the existing 30 mph signs for 20 mph ones (with additional repeaters as required by law) at the Parish Councils expense. If for some reason you feel that you cannot grant this simple request that will cost the County Council nothing (we would not expect an increase in police enforcement of the new speed limit) can you at least implement a school 20 mph zone as proposed by John Lindsay in 2003 and 2004 that is also being promoted by Councillor Tony Blackburn.

As mentioned earlier the need for a crossing was accepted back in 2003 but a suitable site could not be found for one. The notion of an implied crossing was put forwards in 2007 and supported by David Drew the then MP for Stroud, Neil Carmichael our current MP and Councillor Stan Waddington. As I understand it to be effective an implied crossing has to be a clearly defined change in the carriage way that looks like a dedicated pedestrian crossing point. What we actually got is two strips of brown non skid surfacing spaced nearly thirty foot apart within a yellow zigzag school no parking zone. This looks more like a couple of badly filled trenches rather than a crossing point. I think the problem stems from the lack of a pavement on both sides of the road opposite of the school.

In practice the school crossing lady escorts the children from a pavement to the entrance to the school which is off of a small back street which has no pavement. It appears to have been beyond the imagination of your consultants to produce a scheme that embraced this practice. However even a well defined crossing will not overcome the problem that the crossing lady faces of traffic approaching the area too fast. There are flashing school lights before the bend in front of the school but there is no warning of a crossing. I am sure that this problem could be overcome by the addition of repeater lights on the downhill side of the crossing point. Although if a general 20 mph limit proves effective in slowing traffic down (I am not expecting that they will travel at 20 mph) the need for advance warning will be reduced.

I apologise for such a long letter but things have been going on for a long time. To summarise the need to do something about the traffic speed and safety of the school crossing point has been accepted for some time and the Parish Council would welcome any action which could improve the situation.

Yours Sincerely

On behalf of Whiteshill and Ruscombe Parish Councillors

Mrs Helen Dunn,
Clerk to Whiteshill and Ruscombe Parish Council

10. Notes

(1) The RAC Report on Motoring 2007 reported that 73% of drivers thought that speeding in built-up areas was “very serious”, yet 47% admitted to doing (2) http://www.rospa.com/roadsafety/advice/driving/speed_policy.htm
(3) http://www.rospa.com/roadsafety/advice/driving/speed_policy.htm
(4) DCFS (2007) The Children's Plan-Building brighter futures. The Department for Children Schools and Families: The Stationery Office
(5) PACTS (2007) Beyond 2010-a holistic approach to road safety in Great Britain.
(6) Commission for Integrated Transport (2001) Study of European best practice in the delivery of integrated transport
(7) Morrison, D., Thomson, H. and Petticrew, M. (2004). An evaluation of the health effects of a neighbourhood traffic calming scheme, Journal of Epidemiology and Community Health, 58, pp. 837–840
(8) Atkins, WS (2001) European Best Practice in the Delivery of Integrated Transport, Summary Report, London: Commission for Integrated Transport.
(9) Atkins, W. S. (2001) European Best Practice in the Delivery of Integrated Transport, Summary Report, London: Commission for Integrated Transport.
(10) Groll, L (2005) "Traffic calming as a fundamental element for a successful bicycle promotion" "Streets Ahead" conference 12 November 2005, Warrington.
(11) Atkins, WS (2001) European Best Practice in the Delivery of Integrated Transport, Summary Report, London: Commission for Integrated Transport.
(12) Daniel Sauter & Marco Hüttenmoser (2006) . The contribution of good public spaces to social integration in urban neighbourhoods.
(13) Joshua Hart (2008). Driven To Excess. Available from www.driventoexcess.org
(14) Dr. Carmen Hass-Klau (1990), An Illustrated Guide to Traffic Calming p3
(15) http://southwarklivingstreets.org.uk/effectiveness-of-traffic-calming-measures/
(16) Living Streets Policy 01/09, Naked Streets, available from http:www.livingstreets.org.uk
(17) http://www.oxfordmail.co.uk/news/4308526.Police_will_impose_planned_20mph_limits/
(18) London Assembly Transport Committee (2009) Braking Point
(19) http://www.portsmouth.gov.uk/living/8403.html

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