Speed limit

Wednesday

Rory Sutherland

Why driving above the speed limit is a mug’s game 

Imagine you are choosing between two proposed road-improvement plans, but have the budget for only one. Both of the roads mooted for improvement are 20 miles long, and your sole aim is to reduce average journey time by as much as possible. Which would you choose? Someone travelling slowly to begin with has more time on the road to profit from any gain in speed 1) Improving Road A, which increases the average speed from 20 to 25mph (i.e. 25 per cent faster). or 2) Improving Road B, which increases the average speed from 40 to 65mph (62.5 per cent faster). The majority of people, including many experts, instinctively plump

The Spectator

Do 20mph speed limits really save lives?

Within limits Do 20mph speed limits save lives? – A 2018 report by Atkins/AECOM/UCL found that 51% of motorists conformed to the new limit (47% in residential areas and 65% in city centres). – When a 20mph zone replaced a 30mph one the median speed fell by 0.7mph in residential areas and 0.9mph in city centres. It was found that there was insufficient evidence to judge whether the 20mph limit reduced casualties: while accident rates had tended to fall within the zones, the same was true of comparator zones which had remained at 30mph. – Only one area of 20mph zones (in Brighton) had seen a significant fall in casualties