Characteristics of traffic crashes among young, middle-aged, and older drivers.

The relationship between speed and road safety is a highly controversial and emotionally charged subject This report investigates the effects of changes in speed on the number of road accidents or road accident victims It is found that the relationship between speed and accidents or accident victims can be represented by a set of power functions, as postulated in the so called "Power Model" of the relationship between speed and road safety

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Speed and road accidents : an evaluation of the power model

Fatal crash risk for older drivers at intersections.

Older drivers have elevated crash rates and are more likely to be injured or die if they have a crash. Medical conditions and medications have been hypothesized as determinants of crash involvement. This population-based case-control study sought to identify medical conditions and medications associated with risk of at-fault crashes among older drivers. A total of 901 drivers aged 65 years and older were selected in 1996 from Alabama Department of Public Safety driving records: 244 at-fault drivers involved in crashes; 182 not at-fault drivers involved in crashes; and 475 drivers not involved in crashes were enrolled. Information on demographic factors, chronic medical conditions, medications, driving habits, visual function, and cognitive status was collected. Older drivers with heart disease (odds ratio (OR) = 1.5, 95% confidence interval (CI): 1.0, 2.2) or stroke (OR = 1.9, 95% CI: 0.9, 3.9) were more likely to be involved in at-fault automobile crashes. Arthritis was also associated with an increased risk among females (OR =1.8, 95% CI: 1.1, 2.9). Use of nonsteroidal antiinflammatory drugs (OR = 1.7, 95% CI 1.0, 2.6), angiotensin converting enzyme inhibitors (OR = 1.6, 95 CI: 1.0, 2.7), and anticoagulants (OR = 2.6, 95% CI: 1.0, 73) was associated with an increased risk of at-fault involvement in crashes. Benzodiazepine use (OR = 5.2, 95% CI: 0.9, 30.0) was also associated with an increased risk. Calcium channel blockers (OR = 0.5, 95% CI: 0.2, 0.9) and vasodilators (OR = 0.3, 95% CI: 0.1, 1.0) were associated with a reduced risk of crash involvement. The identification of medical conditions and medications associated with risk of crashes is important for enhancing the safety and mobility of older drivers.

Relations among Chronic Medical Conditions, Medications, and Automobile Crashes in the Elderly: A Population-based Case-Control Study

The situational risks of young drivers: the influence of passengers, time of day and day of week on accident rates

Trends in highway safety: Effects of an aging population on accident propensity

Even though the numerator in accident rates can be accurately determined nowadays, the denominator of these rates is an item of discussions and debates within the highway safety community. A critical examination of an induced exposure technique, based on the non-responsible driver/vehicle of a two-vehicle accident (quasi-induced exposure), is presented here. Differences in exposure for a series of accident location and time combinations are investigated, the assumption of similarities between drivers of single-vehicle accidents and the responsible driver of multiple-vehicle accidents is refuted, and the use of the non-responsible driver as a measure of exposure is tested using vehicle classification data. The results of the analyses reveal the following: 1) accident exposure is different for different location and time combinations; 2) induced exposure estimates provide an accurate reflection of exposure to multiple-vehicle accidents; 3) induced exposure estimates are acceptable surrogates for vehicle miles of travel when estimates are made for conditions during which the mix of road users is fairly constant; and 4) the propensity for involvement in single-vehicle accidents is generally different than that in multiple-vehicle accidents for a given class of road users. The authors concluded that the quasi-induced exposure is a powerful technique for measuring relative exposure of drivers or vehicles when real exposure data are missing.

Quasi-induced exposure: methodology and insight

Quasi-induced exposure: Methodology and insight

This report describes the research conducted on permanent deformation of asphalt concrete mixes as part of the Strategic Highway Research Program (SHRP) Asphalt Research Program. Divided into three sections, the report addresses the following: the development of a series of accelerated performance tests to measure the permanent deformation response and a constitutive relationship to define it; validation of the binder properties included in the SHRP binder specification; and the use of the test methodology in an asphalt concrete mix design and analysis system.

Permanent deformation response of asphalt aggregate mixes

This report evaluates test procedures for measuring the fatigue response of asphalt paving mixtures, and summarizes current knowledge of the factors that influence fatigue response. Available test methods are classified, and criteria used to evaluate each method for its potential use as a laboratory standard are discussed. The 3 most promising methods are considered to be simple flexure, diametral fatigue, and tests based on fracture mechanics principles. Factors affecting fatigue repsonse include specimen fabrication, mode of laoding, mixture variables, and loading and environmental variables. Mode of loading, typically either controlled-stress or controlled-strain for laboratory testing, is one of the primary factors affecting fatigue response. Air void content and temperature, both affecting mixture stiffness, may have more significant influence on fatigue repsonse than any other variable. Many mixture, load, and environmental factors also influence fatigue respose and must be considered both in the development of test protocols and in the determination of asphalt and mixture properties that are essential for fatigue-resistant pavements.

John A. Deacon

Papers

Trends in highway safety: Effects of an aging population on accident propensity

Quasi-induced exposure: methodology and insight

Quasi-induced exposure: Methodology and insight

Permanent deformation response of asphalt aggregate mixes

Summary report on fatigue response of asphalt mixtures