Alfred-Shalom Hakkert

Risk of a road accident in rainy weather

A number of methods have been proposed for measuring the added risk of a road accident during rainy weather. These methods are reviewed here, and two of them are applied, with adjustments, to data from Israel and the United States. Their accuracy, however, is limited because surrogates have to be used for traffic exposure to rain. Nevertheless, results to indicate that the added risk of an injury accident in rainy conditions can be substantial: two to three times greater than in dry weather. And when a rain follows a dry spell the hazard could be even greater.

A critical review of macro models for road accidents

This paper presents a critical review of state-of-the-art macro models for road accidents. Such a review is meant to identify and establish the significance of policy and socioeconomic variables affecting the level of road accidents. The aim is to identify those variables associated with effective policies and interventions to enable decision makers to improve the level of road safety. The variables that appear to affect the number of fatalities or injuries are: vehicle miles travelled (VMT), vehicle population, income (in its various forms), percentage of young drivers, intervention policies such as speed limits, periodic vehicle inspection, and minimum alcohol-drinking age. Viewed critically, the state-of-the-art models being used to explain and predict road accidents are still deficient. One possible approach to correcting this deficiency draws from consumer utility theory, using analytical models built on a newly constructed theoretical framework. Success in estimating such models may improve predictions of road accidents, thus demonstrating the comparative cost effectiveness of alternative intervention policies.

Effects of Red Light Cameras on Violations and Crashes: A Review of the International Literature

Red light running is a frequent cause of motor vehicle crashes and injuries. A primary countermeasure for red light running crashes is police traffic enforcement. In recent years, many police agencies have begun using automated red light cameras as a supplement to conventional enforcement methods. The present study reviewed and evaluated available evidence in the international literature regarding the effectiveness of cameras to reduce both red light violations and crashes. Camera enforcement generally reduces violations by an estimated 40-50%. In terms of crash effects, most studies contain methodological flaws that, to varying degrees, either overestimate (failure to adjust for regression to the mean) or underestimate (comparison with nearby signalized intersections affected by cameras) crash effects. Mindful of these limitations, the research generally indicates that camera enforcement can significantly reduce injury crashes at signalized intersections, in particular right-angle injury crashes. Most studies reported increases in rear-end crashes following camera installation. Taken together the studies indicate that, overall, injury crashes, including rear-end collisions, were reduced by 25-30% as a result of camera enforcement.

The evaluation of road-rail crossing safety with limited accident statistics

Safety evaluation is an essential issue in ranking road-rail crossings as candidates for grade-separation. Many small countries like Israel do not possess sufficient data to generate statistical models similar to the US DOT accident prediction formula or others. At the same time, it is desirable to provide estimates stemming from local conditions. For these, available Israeli accident data were artificially enlarged using the unification of accident statistics and information from crossings functioning over a six-year period. A hazard index serves as a basic evaluation tool. The datasets on accidents and crossings are split according to several crossing characteristics (category of warning device, volume of vehicle traffic, volume of train traffic, visibility conditions); the obtained values are combined to supply safety estimates for crossing types defined by these characteristics. The validity of model performance is explored. For Israeli conditions the model provides for a safety evaluation of 168 crossing types. This presents a sufficient base from which to estimate the accident potential of any local crossing when the need for its grade separation is discussed.

The use of road humps for moderating speeds on Urban streets

Road humps are devices placed in the path of traveling vehicles. They are used in many communities to keep a uniform and low speed on a residential street or to reduce speeds at specific locations, such as intersections or pedestrian crosswalks. While the effectiveness of road humps in moderating speeds at the site of installation is generally considered proven, the actual adoption of the device remains controversial at the level of the community and the practicing engineers. The present paper, based on literature review and an international survey, evaluates community acceptance of the device and the factors influencing it; describes the various approaches taken to solve problems such as accommodating public transport and emergency vehicles; and assesses the legal status of the device.

A SYSTEM FOR THE ALLOCATION OF SAFETY RESOURCES ON A ROAD NETWORK

Abstract This paper presents a complete allocation methodology of resources for safety improvements of a road network. In the first part of the paper, a set of models is estimated to identify so-called “black spots” in the road network. In the second part of the paper, a Linear Programming (L.P.) model is defined for the allocation of a total budget to those projects which ensure the most cost-effective results in reducing road accidents. The specific solution method for the allocation L.P. problem is defined, and its superiority to a cost-benefit analysis for budget allocation is shown through a real world example.

Patterns of safety belt usage following introduction of a safety belt wearing law

The paper reviews the process of enacting a safety belt wearing law in Israel, and studies the impact it has had on belt usage and on casualty reductions. Safety belt legislation in Israel had several unique features in that, on the one hand, all passenger vehicles were retrofitted with safety belts, but, on the other hand, it exempted drivers and front-seat passengers of pre-1969 model vehicles from the compulsory use of belts. Also, the legislation applied only to the use of belts on interurban roads. Repeated counts of safety belt usage, before and after the implementation of the law, provided strong evidence for the efficacy of the legislative act as such. Usage rates rose from an average of 6% to upward of 70%. There was a marked carryover effect of the law on belt wearing rates on urban roads and on the use by drivers of pre-1969 model cars. However, this effect diminished with time. Results of a questionnaire survey provided further evidence for the general acceptance of the law by the public. Only a small minority of drivers completely rejected the use of safety belts. A comparison with data from other countries shows that the impact of a compulsory safety belt wearing law on safety belt usage and on casualty reduction is a universal phenomenon. This fact should encourage researchers, legislators and adminstrators in jurisdictions which are still deliberating the value of mandatory safety belt legislation. On the basis of the trends in fatalities and casualties to car drivers and passengers on urban roads during the two and one-half year period following the introduction of the seat belt law, it is estimated that a reduction of 42% in car fatalities and 44% in car passengers occurred on interurban roads during those two and one-half years. The corresponding reductions in casualties were 18% and eight percent respectively.

Development of Evaluation Tools for Road-Rail Crossing Consideration for Grade Separation

A program for expansion of Israeli railways has resulted in increased train speeds and frequencies on the most heavily used railway lines. These are situated in highly populated regions and are characterized by a significant amount of at-grade road-rail crossings. At-grade crossings present a barrier to road traffic and the danger of train-vehicle collisions. Because the current maximum train speed is about 120 km/hr, there was no clear policy concerning the need and the priority for grade separation at crossings. Simplified tools for rapid crossing evaluation when a crossing potential for grade separation is reviewed were developed. The evaluation tools include a criterion for preliminary crossing qualification and a formula for approximate evaluation of economic losses caused by at-grade crossing functioning. The field measurements and detailed investigation of the 31 most problematic locations provided a basis for building the tools. Two main factors leading to grade separation were considered: safety problems at the crossings and road vehicle delay costs. As demonstrated, the cost of accident risk at Israeli crossings does not significantly affect their ranking for grade separation. In consequence, the crossing parameters influence vehicle delays that constitute the basis for the simplified tools for preliminary crossing evaluation in Israel.

Consideration of Bollard Treatment at Exit Gore Areas

The efficiency of bollards—soft plastic post delineators which are installed at exit gore areas of some highways in Israel—is considered. The devices are expected to contribute to better arrangement of traffic streams and to reduce erratic vehicle maneuvers at highway exits. The treatment was examined in three ways: (1) a review of current experience concerning delineation techniques and tools for safety enhancement at exit gore areas, (2) a detailed consideration of accidents occurring on freeways with emphasis on specifics relevant to exit area occurrences, and (3) field observations of driver behavior at exit areas before and after bollard installation. The literature review showed that use of bollards for highway traffic arrangements has not been investigated closely, at least over the past 20 years. However, practice demonstrated that different kinds of delineation treatments did contribute to better traffic operations and decreased the number of erratic maneuvers at exit area approaches. A detailed consideration of accidents for two highways revealed that the accidents occurring at “exit” and “on” areas are a major part of interchange area accidents (69 percent), while explicit “gore area crossing” maneuvers appear only in six cases (23 percent of exit accidents). In total, a potential benefit of bollard application could be relevant to 11 percent of the accidents. Field observations of driver behavior were conducted for two sites. The comparison proved a significant reduction in erratic maneuver rates after the treatment: up to 60 percent in daytime and up to 65 percent at nighttime. Finally, the bollard treatment was recommended for use at freeway exits.