A new report by the International Transport Forum
for the Organisation for Economic Co-operation and Development
(OECD) suggests that lower speeds make roads safer.
The study examined how the road safety performance in 10 countries
changed after they changed speed limits or introduced automatic speed cameras
on a large scale.
All the cases indicated a strong relationship between
speed and the number of crashes: An increase in mean speed was accompanied by a
higher number of crashes and casualties. A decrease was associated with fewer
crashes and casualties. In no case did an increase in mean speed coincide with
fewer crashes or casualties.
These results, said the OECD, confirmed the existing scientific
evidence that speed had a direct influence on the occurrence of traffic crashes
and on their severity.
According to a widely used scientific formula, every 1%
increase in average speed results in a 2% increase in all injury crashes, a 3%
rise in fatal and severe crashes and 4% more fatal crashes.
Thus, reducing speed by a few km/h could greatly reduce
the risks of and severity of crashes, it is claimed.
The report recommended:
- Reduce the speed on roads as well as speed
differences between vehicles
- Set speed limits based on the ‘Safe System’
principles - at a level that humans could survive without dramatic consequences
in case of a crash
- Introduce compensation measures where speed
limits were increased; for instance, stricter enforcement or a safety upgrade
of the road infrastructure;
Use automatic speed control to effectively
Working towards a ‘Safe System’, the authors propose as
reasonable speed limits:
- 30 km/h (20 mph) in built-up and residential
urban areas where motorised vehicles and vulnerable road users share the same
- 50 km/h (30 mph) in other urban areas with
intersections and high risk of side collisions
- 70 km/h (43 mph) on rural roads without a median
barrier and a risk of head-on collisions.
The report notes that lower driving speeds generally
improved peoples’ quality of life, especially in urban areas. They also reduced
emissions, fuel consumption and noise.
The report can be viewed at: https://www.itf-oecd.org/sites/default/files/docs/speed-crash-risk.pdf