Criteria for driver impairment.

This paper proposes and discusses a method of indexing driver impairment. It presents an overview of techniques used to define impairment, including observation, critical incident analysis and psychophysiological criteria. The limitations of these techniques are discussed. Composite variables can be reached that combine different indicators of impairment. The paper considers absolute and relative criteria, assessed against a control condition: and presents categories of driving impairment which might lead to loss of control of the vehicle. In order to measure driver error, driving behaviour must be broken down into quantitative data such as speed or time to collision. Categories of impairment are translated into relative and absolute criteria with respect to selected measures of behaviour. It is proposed that an integrated diagnosis based on information from vehicle sensors could be made using fuzzy logic processing and hence an impairment monitoring device could be developed. For the covering abstract see ITRD E113725 (C 22328 CD-ROM).