PaperQuasi-induced exposure: Methodology and insight
Abstract
Even though the numerator in accident rates can be accurately determined nowadays, the denominator of these rates is an item of discussion and debate 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 (quasiinduced 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.
(1)accident exposure is different for different location and time combinations;
- 2.
(2) induced exposure estimates provide an accurate reflection of exposure to multiple-vehicle accidents;
- 3.
(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.
(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.
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Cited by (125)
Looking back in the rearview: Insights into Queensland’s rear-end crashes
2024, Traffic Injury PreventionRear-end crashes cost the most out of any crash type to the Compulsory Third Party insurance scheme of Queensland. Rear-end crashes are also one of the most common types of crashes, peaking as the most common type of crash in Queensland in 2019. This study investigated the environmental, driver, and vehicle characteristics associated with rear-end collisions in Queensland, Australia.
A totle of 367,230 crashes in the Queensland crash database between 2001 and 2021 were used to identify crash trends in Queensland, particularly related to rear-end crashes. For crashes between 2015 and 2021, additional information was gathered and allowed further analysis of factors contributing to rear-end crashes using the quasi-induced exposure method. Two binary classification tree models were used. Model 1 investigated the environmental characteristics that predicted a crash being a rear-end or not. Model 2 investigated the controller and vehicle characteristics that predict a rear-end crash-involved vehicle to be either the striking (at-fault) or struck (not-at-fault) vehicle.
Model 1 indicated that rear-end crashes were overrepresented in urban areas and major cities and where speed limits exceeded 50 km/h. Model 2 indicated that occupants of struck vehicles (not at-fault) were more likely to be severely injured than the striking (at-fault) vehicles in rear-end crashes. License type and vehicle type also influenced the frequency and severity of rear-end crashes.
Rear-end crashes can be unjust in that the not-at-fault party is typically more severely injured. Results from the current study suggest that keeping speed limits no higher than 50 km/h could help reduce the severity of rear-end crashes. Increased enforcement of safe following distances could also assist in preventing road trauma as a result of rear-end crashes.
Informing traffic enforcement leniency and discretion: Crash culpability and the effectiveness of written warnings versus citations
2023, Accident Analysis and PreventionDeterrence of risky driving behavior is important for the prevention of crashes and injuries. Traffic law enforcement is a key strategy used to decrease risky driving, but there is little evidence on the deterrent effect of issuing warnings versus citations to drivers regarding the prevention of future crashes. The purpose of this study was to 1) investigate the difference between citations and written warnings in their association with future crash culpability and 2) investigate whether drivers who were issued written warnings or citations have different associations with future crash culpability likelihood than those without prior citations or written warnings.
Data for this study included Iowa Department of Transportation crash data for 2016 to 2019 linked to data from the Iowa Court Case Management System. A quasi-induced exposure method was used based on driver pairs involved in the same collision in which one driver was deemed culpable and one was non-culpable. Conditional logistic regression models were constructed to examine predictors of crash culpability. The main independent variable was traffic citation and warnings history categorized into moving warning, non-moving warning, moving citation, non-moving citation, or no citation or warning in the 30 days prior to the crash.
The study sample included a total of 152,986 drivers. Among drivers with moving violations, previously cited drivers were more likely to be crash culpable than previously warned drivers (OR = 1.64, 95% CI = 1.29–2.08). Drivers with prior non-moving citations were less likely to be the culpable party in a crash than a driver who had no recent warnings or citations (OR = 0.72, 95% CI = 0.58–0.89). Drivers with prior warnings (moving or non-moving) did not appreciably differ in crash culpability relative to drivers who had not received any citations or warnings in the previous 30 days.
Drivers with prior moving citations were more likely to be culpable in a future crash than drivers with prior moving warnings, which may relate to overall driving riskiness as opposed to effectiveness of citations in deterring risky driving behaviors. Results from this study also suggest that officer discretion was being appropriately applied by citing the riskiest drivers, while giving lower risk drivers warnings. Results from this study may be useful to support strengthening of state driver improvement programming.
How do road infrastructure investments affect Powered Two-Wheelers crash risk?
2023, Transport PolicyThe drivers of Powered Two-Wheelers (PTWs) pertain to the collective of so-called vulnerable road users. Crashes have scarcely decreased for these roadway users in recent years, whereas among other users, e.g. cars users, they have declined considerably. Meanwhile, the use of PTWs has risen sharply worldwide. This situation adds a further concern to transportation policies and makes evident the need to explore factors involved in PTW crashes. Yet there is a lack of studies specifically about road safety for PTWs. The present study therefore aspires to advance in the knowledge of the factors affecting PTW crashes on interurban roadways, by means of analyzing the effects of some variables not considered previously in this type of studies —mainly economic resources invested in roads—while also accounting specifically for the exposure to risk of PTWs (veh-km), along with relevant variables related to road traffic, the roadway infrastructure, and socioeconomic, meteorological and legislative factors. To this end, and bearing in mind the latest advancements of incorporating unobserved heterogeneity in count data models, different configurations of random parameters negative binomial models for data panels are presented. The realm of study is the network of national roads in Spain, distributed over 43 provinces, and the time period between 2007 and 2015. The results show significant associations for 11 of the variables considered: annual and accumulated investment in construction, expense on maintenance, proportion of motorways, light and heavy vehicle traffic, per capita GDP, age, unemployment rate, price of gasoline, and modification of the demerit point system (DPS). With respect to transport policy implications, the findings provided in this study may serve to monitor the effects of economic resources allocated to road construction and maintenance —along with other measures, such as gasoline prices and DPS—on PTWs safety.
Variation in drivers’ seat belt use by indicators of community-level vulnerability
2023, Journal of Safety ResearchIntroduction: Examining crash reports with linked community-level indicators may optimize efforts aimed at improving traffic safety behaviors, like seat belt use. To examine this, quasi-induced exposure (QIE) methods and linked data were used to (a) estimate trip-level seat belt non-use of New Jersey (NJ) drivers and (b) determine the degree to which seat belt non-use is associated with community-level indicators of vulnerability. Method: Driver-specific characteristics were identified from crash reports (age, sex, number of passengers, vehicle type) and licensing data (license status at the time of the crash). Geocoded residential addresses were leveraged within the NJ Safety and Health Outcomes warehouse to create quintiles of community-level vulnerability. QIE methods were applied to estimate trip-level prevalence of seat belt non-use in non-responsible, crash-involved drivers between 2010–2017 (n = 986,837). Generalized linear mixed models were then conducted to calculate adjusted prevalence ratios and 95 % confidence intervals for being unbelted for driver-specific variables and community-level indicators of vulnerability. Results: Drivers were unbelted during 1.2 % of trips. Males, those with suspended licenses, and those without passengers had higher rates of being unbelted than their counterparts. An increase was observed in traveling unbelted with increasing quintiles of vulnerability, such that drivers in the most vulnerable communities were 121 % more likely to be unbelted than those in the least vulnerable communities. Conclusions: Prevalence of driver seat belt non-use may be lower than previously estimated. Additionally, communities with the highest amount of the population living with three or more indicators of vulnerability have higher rates of seat belt non-use; this may be a particularly useful metric to inform future translational efforts improving seat belt use. Practical Applications: As evidenced by the findings that risk of being unbelted increased as drivers’ community vulnerability increased, novel communication efforts tailored to drivers from vulnerable neighborhoods may optimize efforts.
Driving under the influence of substances and motor vehicle fatalities among older adults in the United States
2023, Traffic Injury PreventionThis study examines contribution of substance use (including alcohol, cannabinoids, stimulants, narcotics, depressants, and hallucinogens) on the probability of drivers being at-fault for a crash on U.S. public roads, with specific emphasis on older adult drivers.
Data from the National Highway Traffic Safety Administration’s Fatality Analysis Reporting System (FARS) for the years 2010–2018 were employed for 87,060 drivers (43,530 two-vehicle crash pairs) involved in two moving vehicle crashes. The quasi-induced exposure (QIE) method was used to compute the relative crash involvement ratios (CIRs) for each relevant substance and illicit drug. Mixed-effect generalized linear regression models were fit to examine the effect of substance use on the probability of a driver being at-fault for a crash.
There were 75.51% males and 73.88% Non-Hispanic Whites in our sample. The CIR for those aged 70–79 years was 1.17, and more than double (2.56) for the ≥80 years old drivers, while being relatively low among drivers of ages 20 to 69. Substance use, in general, disproportionately increased the probability of being at-fault during a crash, regardless of driver’s age. Though older drivers are less likely than other age groups to report substance use, presence of substances among older drivers increased the probability of their being at-fault two to four times during a crash across almost all substances. The regression models, after adjusting for driver’s sex, road grade, weather, light conditions, distraction, and speeding at time of crash, revealed that older drug-impaired drivers were twice as likely to be at fault in a fatal crash (aOR = 1.947; 95% CI = 1.821, 2.082; <0.0001) compared to their middle-aged counterparts. Similarly, most substance use categories were responsible for the probabilities of higher CIRs among the drivers.
These findings necessitate continued efforts to bring awareness to the deadly consequences of “drugged driving,” especially among older adult drivers.
Does age matter? Examining age-dependent differences in at-fault collisions after attending a refresher course for older drivers
2022, Transportation Research Part F: Traffic Psychology and BehaviourThe “Driver 65+” course is a voluntary refresher course offered to all drivers aged 65 years or older in Norway. The current study estimated differences in at-fault motor vehicle collisions (MVCs) between older drivers who had attended in the course and older drivers who had not attended the course.
Two samples of drivers were selected from the database of an insurance company and were sent a questionnaire in the mail. The first sample consisted of 2039 car owners aged 70 years or older who had reported a collision to the insurance company during the last 24 months. The second sample consisted of 1569 drivers aged 70 or older who had not reported any collisions during the last 24 months.
The results indicated an age-dependent effect; drivers attending the course before 75 years of age had a significantly lower risk of being the at-fault driver in a multi-MVC than older drivers who did not attend the course.
The results indicate that the refresher course had a beneficial effect on collision risk for drivers who attended the course before reaching 75 years of age. One possible explanation of this age-dependent effect is that a certain level of visual, cognitive, and motor functioning is needed to implement the strategies learned in the course. However, the design of the study makes it difficult to draw definite conclusions about the causal relationship between course attendance and later collision involvement.