Speed bumps, lower speed limits, and other so-called "traffic calming" strategies may help reduce traffic-related injuries and deaths, according to a review of published studies.
But it's still not clear whether such measures will work in the developing world -- where they may be needed the most, Dr Frances Bunn of the University of Hertfordshire in Hatfield, UK and colleagues note.
Car crashes are the ninth-leading cause of years of life lost to disability in the world, and are expected to jump to third place by 2020, Bunn and her team note.
They searched the literature for studies on the value of speed bumps, mini-roundabouts, lower speed limits, one-way streets and other traffic calming measures.
They found no randomised controlled trials (the gold standard) that compared traffic calming to no intervention, but they did find 22 before-and-after studies. All were done in Europe, Japan or Australia, and none were done in low or middle-income countries.
What the study revealed
The pooled results showed that, after implementation of traffic calming, the risk of fatal traffic accidents fell 21%; fatal or non-fatal accidents resulting in injury were cut by 15%; and the total number of crashes fell by 11%. But there was no significant reduction in the number of car accidents involving pedestrians.
These figures likely underestimate the effect of traffic calming efforts, the researchers say, because the studies they reviewed were so different from one another, making it difficult to pool the results together.
Bunn and colleagues report their findings in The Cochrane Library, which publishes systematic reviews of medical research.
"Traffic calming interventions," the researchers conclude, "need to be properly evaluated using well-designed controlled studies, so that we can more accurately estimate their effects. In addition, researchers need to assess the effect of these interventions in middle and lower-income countries." – (Reuters Health, October 2009)
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