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Abstract
The objective of this study is to identify the relationship between driver, roadway, environmental conditions, and accidents that occur at intersections and then to determine if certain aspects of intersections traffic control affect the aged drivers differently than the non-aged drivers.
The data consisted of 148,134 multi-vehicle accidents that occurred on the State of Michigan Trunkline system. The induced exposure method is used to derive accident involvement to exposure rates. This method is based on the assumption that the accident exposure by any age group of drivers is proportional to the innocent victim (driver not responsible for the accident) involvements in multi-vehicle accidents by that age group of drivers.
Using this technique, conditions are identified in which aged drivers experience higher involvement rates than younger drivers. For these conditions the data are further tested to examine the effect of the intersection traffic controls and their characteristics on the elderly accident involvement.
The results indicate that, in general, elderly drivers do not exhibit different accident patterns between signalized and non-signalized intersections under the conditions tested. Exceptions are female drivers at signalized intersections in snowy weather conditions and middle-old female drivers at non-signalized intersections on multi-lane two way roads. For non-signalized intersection accidents, it was concluded that elderly drivers, and mainly females, experience higher rates at night in snowy weather conditions than either other weather conditions or during the day. For signalized intersection accidents, it was found that elderly drivers experience significantly more problems at signalized intersections with multi-phase signals, while the other signal characteristics had no effect on elderly.
The predominant violation types for aged drivers are following too close, failing to yield the right of way, and improper turning; which indicate a failure to properly identify the available gaps and to properly react to traffic conditions. These violations lead to corresponding accident types, such as rear end, head-on while turning left, and right angle indicating that elderly have problems with turning maneuvers in complex traffic situations. These findings tend to support the hypotheses that elderly drivers experience a reduced ability to appropriately handle traffic situations due to a reduction in the basic skills required for safe driving.
This study documented the fact that elderly drivers experience difficulty as the complexity of the design and traffic control device application increases, indicating that the major contribution to safety may come from measures affecting the driver, such as licensing and training.
