Installations of traffic signals at intersections are often associated with changes in the accident characteristics at those sites. Past studies have indicated a reduction in the severity of accidents, but in some instances accident frequencies have increased. Traffic signals also influence changes in the distribution of accident types. Head-on, left-turn accidents at signalized intersections are of great importance to traffic engineers. A study of newly installed traffic signals was performed in michigan to evaluate the changes in the distribution of accident types, including head-on, left-turn accidents. This study involved statistical testing of before and after accident rates at groups of similar intersections. The results of this study indicated an increase in head-on, left-turn accidents at the group of signalized intersections with and without separate left-turn lanes. However, the rate of increase in such accidents at locations without a separate left-turn lane was not significant at the 95% confidence level. The group of locations in which a separate left-turn lane was installed along with the traffic signals also did not indicate a statistically significant change in the head-on, left-turn accident rate.
Samenvatting