The criteria for reducing speed limits.
The criteria for the introduction of 20mph limits in the speed strategy is that traffic has to be going slow already!! Previously 85% of cars had to be doing 24mph or less for a road to qualify as suitable for this speed limit. Great play has been made of a change in DfT guidance so that the mean or average speed of cars is now the measure of whether 20mph limits can be introduced – the average speed of vehicles must be 24 mph or less. Under the old or new criteria a road is disqualified if cars are going faster – if only 84% were going at 24mph or less, or if the average speed is 25 mph. So, if cars are going slow we can have a speed limit introduced, but not if they are going fast. To introduce a zone, or collection of roads where 20mph can be applied, 90% of the roads must have average speeds of 24 mph or less according to the County’s new draft strategy.
What are the health benefits?
The obvious health benefit is the reduction of collisions and casualties, but the evidence for general health benefits was also reported.
For injuries there is evidence that slower traffic leads to fewer traffic collisions, fewer serious injuries to car occupants, and where a pedestrian is involved fewer serious injuries and deaths at slower speeds. This is summarised by the Royal Society for the Prevention of Accidents RoSPA – fact sheet here and supported in an article from the British Medical Journal – here . This has an impact on medical costs – fewer A&E attendances, admissions and medical care required. In Liverpool the health authority provided financial support for the introduction of 20mph limits because they thought it would cost less to prevent injuries than treat them.
However there are less obvious benefits, but potentially more significant. Lack of physical activity is linked to a number of concerns – heart disease, high blood pressure, diabetes and obesity, amongst others. Within the county is one area where 23% of children at year 6 are regarded as obese. To counter such trends the County’s ‘Active Travel Strategy’ has a target of increasing the number of journeys of under 1 mile which are walked, and the number of journeys under 3 miles which are cycled – click here). The County Public Health representative reported that the Bristol scheme led to a 23% increase in walking and a 20.5% increase in cycling in the pilot areas. So if the target is personal ‘health & wellbeing’ with reduction of the modern diseases related to inactivity, speed reduction is good for all. This message was also broadcast by the National Heart Forum, supported by the national Association of Public Health Directors, in stating it support for the default speed limit in built-up areas being 20mph.