I AM writing in response to last week’s rather more thoughtful letter regarding 20’s Plenty suggesting that a six-month trial should be conducted over a limited area before making a decision.
While on the face of it this seems like a sensible approach, it would actually be a costly mistake.
The problem is that a six-month trial in a limited area would not be sufficient to get an accurate assessment of benefits. To establish the impact on numbers of collisions, injuries and deaths with any reasonable level of statistical confidence would require a longer time period.
It would thus fail in its primary aim of informing a decision on a full scheme. Doing it over a limited area would also fail to be representative of the impact of a town-wide scheme.
Fortunately, there is no need for a trial. In the Netherlands, 30,000km of residential roads now have 18mph (30kph) limits. Research over at least 20 years shows these roads are three times as safe as streets with a 31mph (50kph) limit. Other towns and cities on the Continent have found the same.
In the UK, London now has 400 zones with 20mph limits. A detailed epidemiological study of the impacts of these across a 20-year time frame found a 42 per cent overall reduction in casualties (the figure was higher in the case of young children).
Results from Portsmouth, Warrington, Cambridge and other areas of the UK have led all these areas to introduce 20mph as a default speed limit on residential roads. In fact, 20mph residential limits are to be implemented across the whole of Lancashire.
The evidence is clear, we need to start making our roads safer for our children, older people, pedestrians, cyclists and motorists now. A limited, six-month trial would just add additional expense, provide inconclusive results and leave the majority of Worthing residents without the benefits of safer streets for even longer.