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This paper explores the frequency of occurrence of highway accidents on the basis of a multivariate analysis of roadway geometrics (e.g. horizontal and vertical alignments), weather, and other seasonal effects. Based on accident data collected in the field, a negative binomial model of overall accident frequencies is estimated along with models of the(More)
Many transportation agencies use accident frequencies, and statistical models of accidents frequencies, as a basis for prioritizing highway safety improvements. However, the use of accident severities in safety programming has been often been limited to the locational assessment of accident fatalities, with little or no emphasis being placed on the full(More)
Signing of non-permanent road surface conditions, such as ice, is difficult because hazard formation, location, and duration are unpredictable. Subsequently, many state transportation departments have begun to question the sensibility of expending material and personnel resources to maintain ice warning signs when little proof exists of their effectiveness(More)
Motorcycle fatalities have more than doubled in the United States since 1997--highlighting the need to better understand the many interrelated factors that determine motorcyclists' crash-injury severities. In this paper, using a detailed crash database from the state of Indiana, we estimate probabilistic models of motorcyclists' injury severities in single-(More)
In the US, single-vehicle run-off-roadway accidents result in a million highway crashes with roadside features every year and account for approximately one third of all highway fatalities. Despite the number and severity of run-off-roadway accidents, quantification of the effect of possible countermeasures has been surprisingly limited due to the absence of(More)
This paper presents an empirical inquiry into the applicability of zero-altered counting processes to roadway section accident frequencies. The intent of such a counting process is to distinguish sections of roadway that are truly safe (near zero-accident likelihood) from those that are unsafe but happen to have zero accidents observed during the period of(More)
Accidents occurring on congested urban freeways can have enormous impacts in terms of lost commuter time. This paper presents an appropriate statistical analysis of urban freeway accident frequency and duration and discusses how this analysis can be used to guide management strategies that seek to reduce the traffic-related impacts of accidents. The(More)
This research explores differences in injury severity between male and female drivers in single and two-vehicle accidents involving passenger cars, pickups, sport-utility vehicles (SUVs), and minivans. Separate multivariate multinomial logit models of injury severity are estimated for male and female drivers. The models predict the probability of four(More)
This study explores the differences between urban and rural driver injuries (both passenger-vehicle and large-truck driver injuries) in accidents that involve large trucks (in excess of 10,000 pounds). Using 4 years of California accident data, and considering four driver-injury severity categories (no injury, complaint of pain, visible injury, and(More)