title: Safety effects of section control--an empirical Bayes evaluation.
abstract: The safety effects of section control were investigated at 14 sites in Norway. A before-after study was conducted with the empirical Bayes method in order to control for regression to the mean (RTM). Effects of trend, volumes, speed limit changes and speed cameras at some of the sites in the before period are controlled for as well. For injury crashes a non-significant reduction by 12% was found. The number of killed or severely injured was found to be significantly reduced by 49% at the section control sites. The results indicate that the crash reductions in tunnels (most of which are undersea tunnels with section control on steep downhill segments) are at least of the same magnitude as on open roads. The results are consistent with findings from speed measurements, although the crash reductions are larger than one would expect as a result from the speed reductions. Downstream of the section control sites (up to 3 km in each direction) injury crashes were found to be significantly reduced by 46%. The number of KSI downstream of the section control sites is too small for drawing any conclusions. It is concluded that section control is effective in reducing both speed and crashes, especially serious crashes, and that spillover effects (crash reductions at non-enforcement sites) are more likely to occur than crash migration. The size of the effects that were found should be interpreted with caution because of the relatively short after periods for some of the sites and the sensitivity of the results to the outcomes of individual crashes.
authors.affiliation: Institute of Transport Economics, Department of Safety, Security and Environment, Gaustadalleen 21, 0349 Oslo, Norway.
authors.forename: Alena
authors.initials: A
authors.lastname: Høye
mesh_terms: D000063:Accidents, Traffic / Q000401:mortality* / Q000517:prevention & control* / Q000706:statistics & numerical data; D001334:Automobile Driving; D001499:Bayes Theorem; D004779:Environment Design; D006801:Humans; D009664:Norway / Q000453:epidemiology; D010781:Photography / Q000295:instrumentation*; D012044:Regression Analysis; D012449:Safety; D012926:Social Control, Formal; D014947:Wounds and Injuries / Q000453:epidemiology* / Q000517:prevention & control
keywords: Crash migration; Empirical Bayes; Enforcement; Regression to the mean; Section control; Spillover effects