Irit Hocherman

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.

Prognostic significance of plasma cell morphology in multiple myeloma.

The effect of bone marrow plasma cell morphology at diagnosis on survival time was evaluated in 139 patients with multiple myeloma. According to the morphological classification scheme the patients were categorized as mature (30 patients), immature (76 patients) or plasmablastic (33 patients). The plasmablastic group had an estimated median survival (Kaplan‐Meier method) of 10.9 months, compared with 32.2 months for immature and 60 months for mature types (P = 0.0000). The prognostic value of a morphologic classification in multiple myeloma was further demonstrated by means of a multivariate linear regression analysis of survival data. Expected survival was calculated using clinical features and morphologic subtypes. The estimated survival time for plasmablastic myeloma was shorter by 51.4 months and for immature myeloma patients by 35 months, compared with mature myeloma patients with similar clinical characteristics. Plasma cell morphology at diagnosis is an important predictor of survival duration in patients with multiple myeloma.

Levels of Safety on Interurban Roads

The levels of safety of the main interurban road network in Israel are studied, and 70 percent of the total interurban roads are covered. A macro approach to the relation between road safety and various road categories as reflected in the overall geometric and traffic operational features is presented and is limited to road links. The classification and regression tree (CART) analysis, a nonparametric method that generates a binary tree structure from the data showing the criterion (variables) for each split and giving a pictorial representation of the data, is used as a preliminary tool to illuminate the relation between the variables and road accidents as a measure of safety and to identify meaningful candidate variables for deeper analysis. CART results portray the importance of average daily traffic (ADT) and the need for stratification of ADT in accident modeling. It also indicates probable power function models and highlights some interactive variables and the effect of shoulder type among single ca...

License renewal for older drivers: The effects of medical and vision tests

This study examines the effectiveness of a license renewal program for elderly drivers, based on vision and medical evaluations, in terms of its direct outcomes. The license renewal process of a complete cohort of Israeli drivers aged 65 and up, whose license renewal date fell during 1980 was followed up. It was found that following a protracted and costly renewal process, practically all licenses were revalidated. New driving restrictions were common, mostly related to the use of eyeglasses during driving; however, these restrictions were found to have little practical significance. The findings lead to questioning the policy of targeting the renewal tests for a subgroup of drivers that accounts for a small percentage of the driver population and an even smaller fraction of the accidents.

A MODEL FOR EVALUATING CONFLICT CHARACTERISTICS AT MULTIPLE AIRWAY INTERSECTIONS

Abstract This paper deals with the estimation of the number and distribution of air conflicts at intersecting air routes. A conflict occurs when the spatial separation between two or more airplanes falls below a specified threshold. The number of conflicts may serve as a measure of the controller’s workload and is an important measure of the air traffic control system’s performance. Existing analytical models can solve for either simple planar configuration of airways and complex stochastic arrivals, or complex airway geometry and rather simple assumption of constant aircraft arrivals, but not both. A simulation model was developed in order to cope with three-dimensional spatial geometry of airway intersections, and to account for different aircraft arrival distributions on the airways. The simulation model is first developed for a simple configuration of two intersecting airways, and later extended to cope with a complex airway system composed of multiple intersecting paths. The simulation model includes a simple module which computes the delay caused by correction maneuvres due to potential conflicts.