Wednesday, 30 September 2009

Portsmouth – changing the way we share our streets.


The presentations made yesterday in the Guild Hall in Portsmouth may well have been a pivotal point in road safety and danger reduction in the UK.

Until now, speed management has mainly been implemented by means of localised interventions on streets to make the driver slow down. Whether they are speed cameras, or speed bumps the essential engagement has been with the driver on the road whilst he or she is driving.

Yesterday Portsmouth City Council and the Department for Transport reported on the results from the completely different approach taken by Portsmouth when in March 2008 they completed their setting of all residential roads, bar arterial routes, with a speed limit of 20 mph. No bumps or humps, but most importantly a decision not just made by Traffic Officers but the whole community as they sought a way to deliver lower speeds and a better quality of life for their residents. Quite simply, Portsmouth people decided to slow down wherever people live!

Of course, setting lower speeds with traffic calming is so expensive that one only usually does it where you have excessive speed problems. But when you make the decision as a community to slow down wherever people live then it is inevitable that many streets will already have speeds below 20 mph. In fact in Portsmouth they monitored 159 sites. 102 already had mean speeds of 20 mph or less. 36 were between 20 mph and 24 mph, whilst on a further 21 the mean speed was above 24 mph.

And because of that mix it was found that overall the mean speed for all the roads did not change very much. In fact it reduced by just 1%. But what was very significant was the fact that in those streets where speeds previously were 24 mph or above then a huge 7mph reduction in mean speed was recorded.

Whilst casualties also fell by 15% and total accidents by 13%, more time will be needed to establish statistically significant collision figures. However, the presenter noted the changes in child and elderly casualties in before and after numbers :-

Children (0-15)

Elderly (70+)










All Casualties



Portsmouth’s success is as a community that has debated how the streets should be shared more equitably and go through the due political, democratic and administrative process to take that community commitment and turn it into a framework within which everyone can take their part in making their city a better place to live.

The spaces between our houses, which we call streets, will never be the same in this country. Portsmouth has shown that communities can change their behaviour and sensibly embark on a 20’s Plenty Where People Live initiative that delivers real benefits to every road user. More and more towns, cities and villages are following this trend to put citizenship back into the way we drive and share our roads. People in Portsmouth are perhaps no different from us all. But what they have found is a way to enable them to turn an aspiration for safer and more pleasant streets into a reality. I suspect there will be plenty more similar communities saying 20’s plenty for them as well.

Rod King, 20’s Plenty for Us. 30th September 2009

Tuesday, 1 September 2009

How 20's Plenty works without physical calming


I recently was in discussion with a councillor in Preston whose experience of an isolated signage only scheme led him to believe that physical calming was necessary on any 20 mph limit. Here is my reply. I post it because it may be relevent to other communities :-

I certainly do understand your concern. Many Councillors and officials do have experience of where they have attempted to reduce speeds by simply creating an Experimental Traffic Order and putting signs up. There are many reasons why such an initiative may not produce any appreciable slowing down of vehicles. However to assume from this that 20 mph limits will not work without physical calming is incorrect.

I apologise if I sound a little arrogant, but I have been watching and working on this issue for the last 5 years and in that time I have gained a great deal of insight into what will work and what will not.

Firstly, experience and experiments show that with just signage and no other interventions you will get a 2 mph drop in average speeds. And I agree that this may not be enough on that particular stretch of road to render it safe or anywhere near your target average speed.

So what are the additional interventions, apart from physical calming, which can be employed. These are as follows :-

1) Deliver benefits to the drivers. So often, the drivers whom you are wishing to influence live outside the street concerned. They probably live on a 30 mph street. What degree of respect do you expect them to give the residents of the 20 mph street if you do not equally give the same benefits to their street, family and children. Therefore making an area-wide or authority-wide 20 mph policy for residential roads maximises the % age of drivers who themselves benefit from a 20 mph road. This increases compliance and therefore increases the average speed drop obtained.

2) Engage with your whole community about the benefits of lower speeds. Treat it as a positive enhancement to the quality of life of the residents rather than just an imposition on the drivers. If you are doing this for a whole authority then the democratic process ensures a wide understanding of the issues and a full debate community and press engagement. Then your 20 mph streets can be “owned” by the community rather than being the “mindless acts of a few councillors and officers” (Note that these would not be my words).

3) Widen the benefits of 20 mph in your discussions to go far beyond road safety. It reduces noise, reduces pollution, increases child and elderly mobility, increases the accessibility for those without motor vehicles. All of these are positive and far better to associate with rather than simply going slower to avoid an accident. Remember that the vast majority of motorists have never “killed a child”. It is not therefore in their minds as a possibility. You have to move the debate away from things that most people think will never happen onto things that always happen. You always frighten children when you travel 3ft away from them at 30 mph. You always cause so much more noise at 30 mph. Accelerating up to 30 rather than 20 always makes our streets less pleasant.

4) Use community engagement through the schools. In Portsmouth a leaflet on the 20 mph proposals was distributed to every child in school. It was made something which was then discussed in the family home. “Daddy, if cars go slower, then can we walk to school instead of driving”. The time when people make a commitment about compliance is then moved from the driving seat and into the home. What better place to discuss and agree that going slightly slower until you get to the main road will not cause any real delays, but will increase the safety of your family.

5) Use enforcement. But only when you have done all of the above. Then it is the Police enforcing the community’s rather than the council’s wish. And ACPO have revised their guidelines and are now enforcing 20 mph limits in many towns.

All of these can and do work. The old way was to just put up an isolated 20 mph zone with physical calming. All this measure does is then ask people to “speed up” when they leave the zone and enter a 30 mph street.

The new way is to use the leverage of community aspirations. To recognise that our culture has changed to one that looks for less car-dependency and a better quality of street life. To be smart with our communications and use a basket of interventions, including enforcement. And finally in the minority of places where you may just need some calming then selectively and retrospectively put this in place. Get all of your other things right and this will be minimal.

A better quality for street life for our children, our parents, our disabled, our walker, our cyclists and even ourselves is possible. But we owe it to all of them to be engaging, smart and assertive in our methodology. Simply paving Preston with speed bumps and tables is neither smart, economic or necessary.

And yes, I would be pleased to visit Preston and to talk to councillors and residents about their aspirations for a better street life and how these may be achieved.