Although road accidents are only too frequent, accident data is often insufficient to perform a detailed diagnosis in view of designing remedial measures, or of measuring significant changes after a measure has been applied. Moreover, data collected on past accidents is useless to forecast future unsafety in changing road or traffic conditions. Alternative approaches are therefore needed, based on other data recorded as a complement or a substitute to accident data. One possible alternative approach is the development and use of traffic conflict techniques. TCTs have thus been designed in a dozen countries, mostly European and North American; their principle and their validity have been discussed by researchers and decision-makers alike in a controversy that went on for a number of years. Because of the controversy, the new investigation tool has been thoroughly investigated : TCTs have been compared and field-tested, and finally found useful for diagnosis studies and short-term evaluations. Several users' manuals have been published for different techniques, and some are currently in use in several countries. The present chapters gives an overview of conflict techniques with general definitions and procedures, the more detailed example of one particular technique, and some elements of discussion as to the validity and use of TCTs. (A)
Abstract