I am grateful for a question posted today by Carsten Jasner in response to an earlier post of mine – Seat belts again. It has prompted another look at the data:
Very interesting! But when the number of car occupant deaths increases while the number of all road user deaths decreases how can the number of pedestrians and cyclists [deaths] also increase?
Figure 1, all road accident deaths (excluding motor cyclists), shows that a well-established downward trend was interrupted (by the seat belt law?) and replaced by a slightly rising plateau. After the seat belt law (arrow) total deaths did not fall below the 1983 level until 1991.
Figure 1
(Source of statistics: http://www2.dft.gov.uk/adobepdf/162469/221412/221549/227755/rrcgb2009.pdf)
For many decades, as car ownership increased in Britain the number of people moving about in cars also increased while the numbers moving about on feet or bicycles, and exposed to the risk of road accidents, fell sharply. Part of the decline in walking and cycling can be explained by the shift to car travel; another part by the fact, that as the volume of metal in motion increased, children were withdrawn from the threat, while vulnerable adults, especially cyclists, withdrew themselves. Figure 2 shows a dramatic decline since 1930 in the ratio of pedestrians and cyclists killed to car occupants killed – from 5.95 in 1935 to 0.47 in 2006.
Figure 2
Figure 3 zooms in on more recent years. Between 1970 and 1982 the ratio dropped from 0.96 to 0.81. In 1983, the first year of the seat belt law, the ratio jumped sharply to 1.00, before resuming its historic downward trend, but it did not drop below 0.81 until 1989. This sharp jump is of course exactly what one would expect in the light of the decrease in car occupant deaths and increase in pedestrian and cycling deaths coinciding with the seat belt law noted earlier. The step change in the trend suggests that each year since 1983 the seat belt law continues to deserve credit for the deaths of vulnerable road users, who but for the law would still be with us.
Figure 3
