Modeling Fault Among Bicyclists and Drivers Involved in Collisions in Hawaii, 1986-1991

Abstract

Subsequent to a review of trends in collisions between bicyclists and motorists in Hawaii during the period 1986 to 1991, characteristics of bicyclists and drivers involved in crashes are compared. On the basis of police-reported crash data it can be concluded that bicyclists tend to be young, male, and, not surprisingly, more likely to be seriously injured than motorists in bicycle-motor-vehicle collisions. Bicyclists are much less likely to be attributed with inattention than motorists, and slightly less likely to be attributed with misjudgment or alcohol or drug use than motorists. Bicyclists, however, are much more likely than motorists to disregard traffic controls or go the wrong way on a street just before becoming involved in a collision. Motorists are more likely than bicy- clists to fail to yield, to engage in improper overtaking, or to follow too closely before becoming involved in a collision. The largest proportion of bicycle collisions occurs during the period 3:30 to 6:30 p.m. Other temporal and locational features of bicycle collisions are described. Among the most significant findings presented is that motorists in Hawaii are much more likely to be classified at fault than bicyclists. Whereas motorists are at fault in approximately 83.5 percent of incidents, bicy- clists are at fault in only 16.5 percent of incidents. A logistic model is developed and used to explain the likelihood of motorists being at fault in collisions with bicyclists. Covariates that increase the likelihood of motorist fault include motorist age (squared), bicyclist age, bicyclist hel- met use, and motorist turning actions. Variables that decrease the likeli- hood of motorist fault include motorist age, bicyclist age (squared), bicy- clist alcohol use, bicyclists making turning actions, and rural locations. Despite the possibly ideal environment Hawaii presents for bicy- cling, the bicycle is losing ground to automobiles and other motor- ized forms of transportation in the state. Although there has been growth in recreational, off-road cycling, the use of bicycles for com- muting and short-distance trips in Hawaii has declined steadily. The moped has found greater acceptance than the bicycle as a low-cost alternative to the automobile ( 1). With its year-round temperate climate, concentrated pattern of development, and its population's health-conscious attitudes and lifestyles, Hawaii could be a bicy- clist's paradise, but it is not. One of the reasons the bicycle has not gained greater prominence in Hawaii is the risk associated with bicycling (2). Bicycling in Hawaii is perceived by many to be dangerous. Moreover, the described study found that in the major- ity of police-reported collisions between bicycles and motor vehicles more often than not the driver of the motor vehicle is at fault. Motorists are at fault approximately 83.5 percent of the time, whereas bicyclists are at fault 16.5 percent of the time. Many bicy- clists may feel that they are fighting a losing battle, and that it is better to stay off the roads and streets of Hawaii. The research described intended to seek a better understanding of bicycle colli- sions in Hawaii so that an initial step could be taken in the design