SAFETY EFFECTS OF RUMBLE STRIPS ON SECONDARY ROADS

Research was undertaken to identify specific locations where rumble strips could improve safety on rural secondary roads. Of the 685 rumble-strip installations on secondary roads in Iowa, 207 were selected for detailed study. At 88 locations a before-and-after comparison of the accident experience was made because accident records were available for at least one full year both preceding and following the installation of rumble strips. (Accident records were available only for 1977-1980.) The accident experience at the 119 locations that have rumble strips installed before 1978 was compared with a sample of comparable locations that do not have rumble strips. No difference was found in the accident experience at secondary road locations between the periods before and after the installation of rumble strips. Secondary road locations that have rumble stiprs for longer periods experienced slightly more accidents than did comparable control locations that did not have rumble strips. Comparisons were made on the basis of both the total number of accidents and the number of accidents attributed to running a stop sign. Futhermore, no correlation could be demonstrated between the occurrence of accidents at the locations in the sample and factors such as traffic volume, sight distance, and distance from the last stop. (Author)