DEVELOPMENT OF HAZARDNESS INDEX MODEL USING TRAFFIC CONFLICT TECHNIQUE

Abstract

The poor status of accident data in terms of its reporting level and further maintenance has hindered all the efforts in safety research. The problem is much a.ggrez7ated when the same is considered in particular reference to India. The concept of accident- prone locations in road safety research is well known. Safety research in terms of identifying hazar-dous locations and consequent improvement has always fallen behind the actual happenings of accidents. Because of the defused and unreliable information available, effective methods could not be developed. Further the developed countries are also finding it extremely, costly to manage collection and maintenance of detailed accident records. Traffic. Conflict Technique (TCT) first developed almost two a decades ago has gone a long way in highway safety research. A traffic conflict is a traffic event which precedes-any accident It is the event which is resulted as a driver percieves a danger of collision and consequently he maneuvTes the vehicle in an unusual and confused manner to avoid the possible collision. Even if a traffic accident is averted in this process, the induced hazardness due to conflict occurance can not be denied. This, nature of safety hazard can not be covered with accident data analysis. Thus traffic conflicts are a better measure of road traffic hazard. In this study a Traffic Conflict Technique has been devised which is best suited for mixed traffic flow conditions in India. A large number of safety variables are identified and Traffic Conflict survey conducted over a number if intersections which are the bottlenecks and the peak conflict generating locations of the road-network. Precise observations of traffic conflict behaviour have been obtained by the use of Time lapse photography technique whereas other relevent data have been collected by manual observations. Relative severity of different conflict types and vehicle categories are established as Equivalent Conflict Units (ECU) and Equivalent Vehicle Units (EVU). The individual and combined correlations of different traffic variables with the conflict rate have been derived. After establishing the validity of a traffic factor its contribution to the total hazard for each of the selected locations has been obtained. A traffic conflict is an outcome of a number of roadway and traffic variables acting simultaneously. Moreover it has direct relation with traffic hazard. This way in the process of identification of hazardness location and consequent improvements, one has a much reduced numl-er of variables to deal with if TCT is employed making it easier and more econo-mical for implementation. While accurate accident data is extremely costly in terms of time and money, Traffic conflict as a surrogate has tremendous potential. Less expensive conflict data collected in ongoing basis will facilitate ready evaluation of hazardness of highway locations at minimum cost. A hazardness index model has been designed and suggested as a comprehensive tool to evaluate the safety of a roadway location.