Evaluation of accident black spot treatments.

In 1979 an Accident Black Spot Program was initiated in Victoria. The program aims to reduce the incidence and severity of casualty accidents at locations with a bad accident record through the use of low cost, highly effective crash countermeasures. The primary purpose of this study is to evaluate the effectiveness of particular types of treatments at various types of locations, with a range of accident types. Effectiveness is measured in terms of both changes in reported casualty accident frequencies and economic worth of the treatments implemented. An efficient, computer-based method for evaluation has been developed as part of this study. The results provide practical and objective information for the refinement of the methods for selection of sites and treatments and, ultimately, to intelligently set directions and establish appropriate emphases for the program. The accident evaluation indicates that the intersections component reduced casualty accident occurrence by 33 per cent overall. Substantial casualty accident savings were derived from new roundabouts (81 per cent reduction), new intersection signals (53 per cent) and remodelled intersection signals (33 per cent), with fully controlled right-turn phases seeming to contribute the bulk of the savings for remodelled signals. The treatment of intersections outside of the Melbourne Metropolitan area produced a 69 per cent reduction, compared to a 30 per cent reduction in the Metropolitan area. The main findings of the economic evaluation are that the intersections component of the Program resulted in BCR values of 8.8 overall, 7.1 for intersections in Metropolitan Melbourne and 19.1 for intersections outside of the Metropolitan area. BCR values of 7.5 for new roundabouts, 8.2 for new intersection signals, and 22.1 for the remodelling of existing signals were achieved. The evaluation found average NPW values per treatment of $0.72 million overall, $1.25 million for new roundabouts, $1.06 for new intersection signals and $0.85 million for remodelled intersection signals. The treatment of midblock locations was unsuccessful overall in reducing casualty accident frequency at treated sites. This aspect warrants more detailed study (Author/publisher).