Does lowering speed limits really help de crease the risk and severity of a crash?
Current and past research in Australia and internationally provides compelling evidence that increased travel speeds – even at low levels – are directly related to both the likelihood of a crash occurring and to the severity of crash outcomes.
Many researchers have demonstrated that lower travel speeds and death tolls usually follow lowering of speed limits and higher travel speeds and death tolls follow increases in speed limits. During the 1970's energy crisis, the maximum speed limit was reduced across the United States of America (USA) from 70 miles per hour (113 km/h) to 55 miles per hour (89 m/h) and the National Highway Traffic Safety Administration board issued a special report, pointing out that this reduction in maximum speed had resulted in a 16.4 percent drop in fatalities. In 1987, the USA lifted the speed limit on rural interstates to 65 miles per hour (105 km/h), which led to a 17 per cent rise in fatalities. A report appearing in the American Journal of Public Health in 2009 has found that a 3.2 per cent increase in road fatalities was attributable to the raised speed limits on all road types in the United States, resulting in 12,500 more deaths between 1995 and 2005.
In 1987, Victoria raised the speed limit on its rural and outer Melbourne freeway network to 110 km/h from 100 km/h. There followed an increase in casualties (including fatalities) of 24.6 per cent. In late September 1989, a 100 km/h limit was reintroduced, resulting in a reduction in crashes of 19.3 per cent. In NSW, recent experience shows that reducing speed limits is an effective measure in reducing the number and severity of crashes including the 26 per cent reduction in casualty crashes on the Great Western Highway after speed limits were reduced from 110 to 100 km/h.