Some of you may have seen the weekend papers which ran stories on this report from Queen's University Belfast. In fact the report in the Queen' s University website had exactly the headline shown above. It was a report that reviewed available previous research on 20mph zones and limits. It reviewed 9 20mph "Zone" reports and 2 20mph "limit" reports. Its conclusion was :-

"This review suggests 20 mph ‘zones’ are effective in reducing collisions and casualties. However, it provides insufficient evidence to draw conclusions on the effect of 20 mph ‘zones’ on pollution, inequalities or liveability. For 20 mph ‘limits’ more rigorous evaluations are required in order to draw robust conclusions."

Basically it was saying that the 2 reports used on 20mph were not thorough enough to draw "robust" conclusions. One of these reports was the Atkins report which we have also criticised for not being thorough enough to be meaningful. Much of our criticism of Atkins can be seen in a previous blog where we call-out the questions which still need to be answered.

However, a few newspapers took the Queen's University report on the proven benefits of 20mph zones and turned it into an attack on 20mph limits which the report had not given any conclusions on other than to say that the 2 research papers it had reviewed were not conclusive.

Typical headlines were :-

The Times - 20mph limit only works with speed humps

The Mail - Reduced 20mph speed limits are useless because drivers ignore them unless speed humps are also built, study says

So here we have a report which clearly says "we have no conclusive evidence" being turned by the press into "evidence that 20mph limits don't work".

1. It confirms that the Atkins Report (commissioned under Chris Grayling) was very inadequate. See our previous blog.
2. There seems to be a complete misunderstanding by newspapers concerned that lack of evidence is not evidence of lack of effectiveness
3. No comparison at all of cost effectiveness. Physical calming is 50 times more expensive and therefore covers 50 times smaller area for the same cost.
4. No comparison of emissions consequences. Physical calming increases emissions, whilst 20mph limits decrease emissions.

There is no recognition that whilst 3) and 4) refer to older physically calmed zones, with current DfT guidance there may be little effective difference between 20mph zones (only requiring 1 physically calmed device per zone) and 20mph limits (requiring one less ,ie zero, physical calming devices per limit). This greying of distinction between zones and limits has enable many authorities to favour 20mph zones with little physical calming because it informs drivers of being in a low speed "area" rather than on a single road.