This report is an analytical study of the frequency of rural single-vehicle accidents in which the vehicle ran off roads in Illinois during 1963. If two or more events occurred by which this type of accident could be classified, preference was given to the first event that happened on the road, i.e., ran off road. The motor vehicle may have collided with persons, objects, or vehicle etc., after leaving the road with resultant injury or damage, or both. Whether the motor vehicle left the road accidentally or to avoid collision is irrelevant in classifying the event, however. The study was confined to those accidents occurring in rural locations, since urban mishaps of this type accounted for but 2 per cent of the total. By contrast, ran-off-road accidents represented 17 per cent of all rural and nearly 23 per cent of fatal mishaps reported during the year. Differences of conditions and circumstances associated with the accident type in rural locations were separated into occurring on numbered State highways and those occurring on other than numbered State highways and those occurring on other than numbered State highways.
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