Risk perception and impulsivity: association with risky behaviors and substance abuse disorders

Low risk perception and high impulsivity, in conjunction with substance abuse disorders, are associated with the occurrence of injury in the general population. The study described in this article investigated the association of risk perception and impulsivity with risky behaviors (infrequent seat belt use, drinking and driving, riding with a drunk driver, binge drinking, and speeding for the thrill) among adults with unintentional blunt trauma. Patients (N = 756) were assessed for substance abuse disorders and participation in risky behaviors. Risk perception and impulsivity were measured by questionnaire. Pearson's chi-square statistic was used to investigate risk perception, impulsivity, substance abuse, and possible confounders relative to risky behaviors. Odds ratios were calculated using logistic regression methodology. Univariate results indicated that low risk perception and high impulsivity were significant risk factors for risky behaviors. After adjustment for confounding factors, low risk perception and high impulsivity remained significantly associated with risky behaviors in the trauma patient population.     

General deterrence effects of U.S. statutory DUI fine and jail penalties: long-term follow-up in 32 states

INTRODUCTION: We examined effects of state statutory changes in DUI fine or jail penalties for firsttime offenders from 1976 to 2002. METHODS: A quasi-experimental time-series design was used (n=324 monthly observations). Four outcome measures of drivers involved in alcohol-related fatal crashes are: single-vehicle nighttime, low BAC (0.01-0.07g/dl), medium BAC (0.08-0.14g/dl), high BAC (>/=0.15g/dl). All analyses of BAC outcomes included multiple imputation procedures for cases with missing data. Comparison series of non-alcohol-related crashes were included to efficiently control for effects of other factors. Statistical models include state-specific Box-Jenkins ARIMA models, and pooled general linear mixed models. RESULTS: Twenty-six states implemented mandatory minimum fine policies and 18 states implemented mandatory minimum jail penalties. Estimated effects varied widely from state to state. Using variance weighted meta-analysis methods to aggregate results across states, mandatory fine policies are associated with an average reduction in fatal crash involvement by drivers with BAC>/=0.08g/dl of 8% (averaging 13 per state per year). Mandatory minimum jail policies are associated with a decline in single-vehicle nighttime fatal crash involvement of 6% (averaging 5 per state per year), and a decline in low-BAC cases of 9% (averaging 3 per state per year). No significant effects were observed for the other outcome measures. CONCLUSIONS: The overall pattern of results suggests a possible effect of mandatory fine policies in some states, but little effect of mandatory jail policies.     

Pedestrian environment and behavior in Karachi, Pakistan.

Pedestrian road traffic accidents (RTAs) are responsible for a substantial number of injuries and deaths in Karachi. To better understand the situations facing pedestrians we selected ten of Karachi's highest risk locations for pedestrian RTAs and observed 250 pedestrians for each of three activities--crossing the street, walking on the street, and walking on the sidewalk. We also observed the extent and effect of street and sidewalk encroachments. A total of 35% of the pedestrians crossing the street caused traffic to swerve to avoid them. Pedestrians crossing one lane at a time were 2.9 times more likely to cause the traffic to swerve than pedestrians who crossed the whole street at once (53 vs. 18%, RR = 2.9, 95% CI = 1.9-4.3). Pedestrians crossing in a group were 1.8 times more likely to cause traffic to swerve compared to those crossing singly (49 vs. 28%, RR = 1.8, 95% CI = 1.3-2.5, P = 0.001). A total of 36% ran while crossing and were 1.8 times more likely to cause traffic to swerve than those who walked (48 vs. 27%, RR = 1.8, 95% CI = 1.3-2.5). An average of 77% of the sidewalk width was blocked by encroachments which forced pedestrians to step on the road resulting in vehicles swerving. An average 33% of the street width was blocked by illegally parked vehicles. Pedestrians in Karachi indulge in risky behaviors. Encroachments on streets and sidewalks compound the problem. Piloting efforts to modify pedestrian behavior and the environment they negotiate should be considered to reduce pedestrian deaths.     

Alcohol/drug abuse, driving convictions, and risk-taking dispositions among trauma center patients

The objective of this study was to evaluate the relationship between alcohol/drug abuse diagnoses, driving convictions (speeding, reckless driving, impaired driving, license violations), and risk-taking dispositions among a series of injured drivers admitted to a trauma center. The driving records of 778 patients were linked to diagnoses of psychoactive substance use disorders (PSUDs), admission blood alcohol concentration (BAC), mode of injury, and results of a risk-taking disposition survey. Twenty-nine percent of patients had one or more convictions in the 3 years before injury. Types of violation were not related to mode of injury. Although there was a positive association between prior impaired-driving convictions, current alcohol dependence, and a BAC+ status, a consistent pattern relative to other violations, PSUDs, and BAC status was not apparent. Risk-taking disposition scale scores indicated that patients without PSUDs and without convictions tended toward less risk-taking behavior than patients with PSUDs and with convictions. The complex inter-relationships between PSUDs, risk-taking dispositions, and being convicted of driving dangerously require additional study so that intervention programs and injury prevention initiatives can be targeted effectively.     

Primary prevention of drink driving by the large-scale use of alcolocks in commercial vehicles

Alcolocks are commercial breath test devices that prevent a motor vehicle from starting when a driver's blood alcohol concentration (BAC) is elevated. This report is an evaluation of the experiences and BAC data from the first use of alcolocks in commercial vehicles as a primary prevention strategy. In most applications, the alcolock is imposed only after an impaired driving conviction. This study, implemented in Sweden, estimates drink driving on a large scale in a variety of commercial vehicles. Officials from 118 companies were interviewed representing 3689 alcolock-equipped vehicles used by 9614 professional drivers, an 80% compliance rate. In a contrast group of 230 transport businesses without alcolocks the interview compliance rate was 57%. Survey results probed motivation for and experience with alcolocks. Analysis of BAC test patterns showed alcohol consumption among employees through prevalence estimates of drink-driving attempts at the rate of BAC> or =the legal limit 0.020%. Before alcolock installation, 64% of the employers suspected alcohol problems among their employees and their motive for installing alcolocks (cost averaged 1700 euro/vehicle) was to improve the transport quality. Several companies had technical problems with the alcolocks; but 98% recommended that other companies install alcolocks. Among 600, heavy vehicles, 0.19% of all starts were prevented by elevated BAC; most during weekends and mornings. Daytime Saturday and Sunday mornings 0.72% of the drivers had elevated BAC. CONCLUSIONS: The prevalence of drink driving among professional drivers is probably similar to that among drivers in general. Alcolocks would improve the safety margin and reduce public risk. Provided that the entire fleet of trucks, buses, and taxis in Sweden had installed alcolocks that would correspond to about half a million drink driving trips being prevented every year.     

The influence of alcohol, age and number of passengers on the night-time risk of driver fatal injury in New Zealand

Breath alcohol measurements and other data collected at randomly selected roadside sites were combined with data on fatally injured drivers in crashes occurring on the same weekdays and times (Friday and Saturday nights) at locations matched by the size of the nearest town. A logistic model was fitted to these data for the years 1995-2000 to estimate the effects of alcohol, driver's age and the influence of passengers carried on the risk of driver fatal injury in New Zealand. The estimated risks increased steeply with increasing blood alcohol concentration (BAC), closely following an exponential curve at levels below about 200mg/dl (i.e. 0.2%) and increasing less than exponentially thereon. The model fitted to data for drivers under 200mg/dl showed that risks at all BAC levels were statistically significantly higher for drivers aged under 20 (over five times) and for drivers aged 20-29 (three times) than for drivers aged 30 and over. Further, controlling for age and BAC level, driving with a single passenger was associated with approximately half the night-time risk of driver fatal injury relative to driving either solo or with two or more passengers. According to a recent travel survey, the types of passengers carried at the times of night and days of week studied appear to differ significantly from the types of passengers carried generally, which may lead to different passenger effects on driver behaviour. The high relative risk of teenage drivers means that they reach high risk levels commonly regarded as unacceptable in the field of road safety even at their current legal limit of 30mg/dl, particularly when more than one passenger is carried in the car.     

The fatality and injury risk of light truck impacts with pedestrians in the United States

In the United States, passenger vehicles are shifting from a fleet populated primarily by cars to a fleet dominated by light trucks and vans (LTVs). Because light trucks are heavier, stiffer, and geometrically more blunt than passenger cars, they pose a dramatically different type of threat to pedestrians. This paper investigates the effect of striking vehicle type on pedestrian fatalities and injuries. The analysis incorporates three major sources of data, the Fatality Analysis Reporting System (FARS), the General Estimates System (GES), and the Pedestrian Crash Data Study (PCDS). The paper presents and compares pedestrian impact risk factors for sport utility vehicles, pickup trucks, vans, and cars as developed from analyses of US accident statistics. Pedestrians are found to have a two to three times greater likelihood of dying when struck by an LTV than when struck by a car. Examination of pedestrian injury distributions reveals that, given an impact speed, the probability of serious head and thoracic injury is substantially greater when the striking vehicle is an LTV rather than a car.     

Road traffic injuries in an urban area in Mexico. An epidemiological and cost analysis

The objective of this study was to do an epidemiological and costs analysis of the impact of road traffic injuries on the demand for emergency room services at hospitals located in the city of Cuernavaca, Mexico. The studied population included injured people who demanded medical attention at the emergency room for injuries due to events in public places, occurring between February and April 2001. Trained interviewers collected the data at the emergency room, 24h a day. The statistical analysis included simple and bivariate analysis using chi(2) odds ratio (OR), and a confidence interval of 95%. The costs analysis included the expenses during the process of searching for and finding care for injuries. There were 433 injured people, 233 (54%) were victims of road traffic accidents, 72% of crashes, and 28% were injured pedestrian and cyclists. Variables associated with the demand of emergency care due to road traffic injuries in comparison with other accidents, were: severity of injuries (OR 2.60, CI 1.44-4.71), and thorax injury (OR 4.64, CI 1.03-20.89). Pedestrians had higher costs for health care and 80% of them had to pay out-of-pocket (P<0.05). Differences between patients injured by crashes or as a pedestrian, were: age under 14 years (OR 5.9, CI 2.5-13.9), being unemployed (OR 2.1, CI 1.20-3.96), and being an elementary school student (OR 13.9, CI 3.08-63.13). The present study is, so far, the only one in Mexico to include an epidemiological and costs analysis in approaching the problem of road traffic injuries. Similar methods must be used, especially in developing countries, to reduce this important public health problem.     

Seeing pedestrians at night: Visual clutter does not mask biological motion

Although placing reflective markers on pedestrians’ major joints can make pedestrians more conspicuous to drivers at night, it has been suggested that this “biological motion” effect may be reduced when visual clutter is present. We tested whether extraneous points of light affected the ability of 12 younger and 12 older drivers to see pedestrians as they drove on a closed road at night. Pedestrians wore black clothing alone or with retroreflective markings in four different configurations. One pedestrian walked in place and was surrounded by clutter on half of the trials. Another was always surrounded by visual clutter but either walked in place or stood still. Clothing configuration, pedestrian motion, and driver age influenced conspicuity but clutter did not. The results confirm that even in the presence of visual clutter pedestrians wearing biological motion configurations are recognized more often and at greater distances than when they wear a reflective vest.     

Guardrail influence on pedestrian crossing behavior at roundabouts

Pedestrians account for 10–30% of all road accident fatalities in western countries, and therefore efforts to improve pedestrian safety are of major importance. Research can support these efforts in various ways, particularly by studying road crossing patterns, and by exploring pedestrian compliance rates to safety laws and guidelines.     

Exploring factors affecting pedestrians’ red-light running behaviors at intersections in China

Pedestrians’ Red-light running behavior is one of the most critical factors for pedestrian involved traffic crashes at intersections in China. The primary objective of this study is to explore how various factors affect pedestrians’ red-light running behaviors at intersection areas, using the data collected from Hefei, China. A questionnaire was well designed aiming at collecting pedestrians’ socio-economic characteristics, trip related features, and attribute variables in different crossing facilities. Based on 631 valid samples, a binomial logistic model was established to evaluate the impacts of contributing factors on pedestrians’ red-light running behavior. The modeling results show that four variables significantly affect the probability of pedestrians’ red-light running behavior, which are the trip purpose, time period in one day, pedestrian’s attitude towards whether to run a red light when in hurry, and pedestrian’s attitude towards whether quality of road facility affects crossing behavior. With those variables, the probability of pedestrians’ red-light running behavior at intersections could be predicted. Findings of this study can help understand why pedestrians in China run red-lights and identify which pedestrian groups and intersections are more likely to have such behaviors. This study can also help propose countermeasures more efficiently to reduce pedestrian-related crashes at intersections in China.     

Factors affecting pelvic and thoracic forces in near-side impact crashes: a study of US-NCAP, NASS, and CIREN data

The goal of this study was to identify variables related to vehicle design which are associated with pelvic and thoracic accelerations as measured by the driver's (near side) crash dummy during new car assessment program (NCAP) testing of motor vehicles. Vehicle specific parameters were analyzed using NCAP side impact test results. Data from national automotive sampling system, crashworthiness data system (NASS-CDS) and crash injury research and engineering network (CIREN) (both National Highway Traffic Safety Administration (NHTSA) injury databases) were assessed to confirm NCAP test observations. In addition, door armrest stiffness measurements were performed using a mechanical tester on a sample of 40 vehicles. NCAP data showed that of 10 variables tested using multiple linear regression, vehicle weight and door crush correlated with pelvic acceleration of the driver's crash dummy (overall, r2=0.58, p=0.002, n=165). For thoracic trauma index (TTI) vehicle weight and peak door velocity correlated, significantly (overall, r2=0.41, p=0.03, n=165). Mean TTI was 63.7 g with no side airbag (n=108) and 55.6 g with a thoracic side airbag (n=54), p=0.01. The mean vehicle weight and door crush between airbag and no airbag groups were not significantly different. NASS-CDS data demonstrated a direct relationship between increased door crush and increased abbreviated injury score (AIS). CIREN data showed that occupants who sustained pelvic injuries had a median AIS of 3 with 24.9 cm of door crush, with abdominal injuries, a median AIS of 3 and 30 cm of crush, and with thoracic injuries, a median AIS of 4 and 34 cm of door crush. In addition, the frequency of bilateral pelvic injuries was significantly higher for subjects in CIREN crashes who were in a vehicle with a center console, but only if door intrusion was greater than 15 cm. This information may be useful in design of vehicles with greater protection in side impact crashes.     

Alcoholism at the time of injury among trauma center patients: Vehicular crash victims compared with other patients

A structured in-depth interview employing standardized criteria was used to determine the prevalence of lifetime and current alcohol dependence (alcoholism) in unselected consecutive patients admitted to a regional Level I trauma center. Of 629 patients, 157 (25.0%) were current alcoholics at the time of injury. An additional 87 (13.8%) were diagnosed as lifetime non-current alcoholics. There was no significant difference in the rates of current alcohol dependence among patients injured in vehicular crashes (23.5%), other unintentional trauma victims (29.3%), and those injured as a result of violence (24.6%). Of BAC + (blood alcohol concentration positive) patients, 54.5% were current alcoholics. However, 14.4% of alcohol-negative patients were also diagnosed as alcohol dependent.     

Pedestrian injuries and vehicle type in Maryland, 1995-1999

Pedestrian deaths constitute the second largest category of motor vehicle deaths in the US. The present study examined how pedestrian injury is associated with vehicle type, while controlling for vehicle weight and speed.Police, trauma registry, and autopsy data were linked for injured pedestrians. Logistic regression analyses were performed to control for vehicle weight and speed. Outcomes included pedestrian mortality, injury severity score, and injuries to specific body regions.Compared to conventional cars, pedestrians hit by sport utility vehicles and pick-up trucks were more likely to have higher injury severity scores (odds ratio=1.48; 95% confidence interval: 1.18-1.87) and to die (odds ratio=1.72; 95% confidence interval: 1.31-2.28). These relationships diminished when vehicle weight and speed were controlled for. At lower speeds, pedestrians struck by sport utility vehicles, pick-up trucks, and vans were approximately two times as likely to have traumatic brain, thoracic, and abdominal injuries; at higher speeds, there was no such association.The overall increased danger sport utility vehicles and pick-up trucks present to pedestrians may be explained by larger vehicle masses and faster speeds. At slower speeds being hit by sport utility vehicles, and pick-up trucks, and vans resulted in specific injuries, indicating that vehicle design may contribute to different injury patterns.     

Firearms in US homes as a risk factor for unintentional gunshot fatality

This study used national data and a matched case-control design to estimate the relative risk of death by an unintentional gunshot associated with having firearms in the home. A sample of adults who died in the United States in 1993 from unintentional gunshot injuries was drawn from the National Mortality Followback Survey (NMFS) (n=84). Twenty controls were sought for each case from the 1994 National Health Interview Survey (NHIS) and matched to the cases by sex, age group, race, and region of residence (n=1451). Subjects were classified as having or not having guns in the home based interview responses. The relative risk of death by an unintentional gunshot injury, comparing subjects living in homes with and without guns, was 3.7 (95% confidence interval (CI)=1.9-7.2). Adjustment for covariates resulted in little change in the effect estimates. There was evidence of a dose-response effect: compared to subjects living in homes with no guns, the relative risk was 3.4 (95% CI=1.5-7.6) among subjects with one gun and 3.9 (95% CI=2.0-7.8) among subjects with multiple guns in the home. Having handguns in the home was associated with the largest effect estimates. Tests of homogeneity showed that the effect estimates did not vary significantly across categories of the matching variables. Firearms in the home appear to be a risk factor for unintentional gunshot fatality among adults. The magnitude of the observed effect estimates should be compared with those from additional studies.     

Impairment of simulated motorcycle riding performance under low dose alcohol

Crash statistics that include the blood alcohol concentration (BAC) of vehicle operators reveal that crash involved motorcyclists are over represented at low BACs (e.g., ≤0.05%). This riding simulator study compared riding performance and hazard response under three low dose alcohol conditions (sober, 0.02% BAC, 0.05% BAC). Forty participants (20 novice, 20 experienced) completed simulated rides in urban and rural scenarios while responding to a safety-critical peripheral detection task (PDT). Results showed a significant increase in the standard deviation of lateral position in the urban scenario and PDT reaction time in the rural scenario under 0.05% BAC compared with zero alcohol. Participants were most likely to collide with an unexpected pedestrian in the urban scenario at 0.02% BAC, with novice participants at a greater relative risk than experienced riders. Novices chose to ride faster than experienced participants in the rural scenario regardless of BAC. Not all results were significant, emphasising the complex situation of the effects of low dose BAC on riding performance, which needs further research. The results of this simulator study provide some support for a legal BAC for motorcyclists below 0.05%.     

Factors associated with hit-and-run pedestrian fatalities and driver identification

As hit-and-run crashes account for a significant proportion of pedestrian fatalities, a better understanding of these crash types will assist efforts to reduce these fatalities. Of the more than 48,000 pedestrian deaths that were recorded in the United States between 1998 and 2007, 18.1% of them were caused by hit-and-run drivers. Using national data on single pedestrian-motor vehicle fatal crashes (1998–2007), logistic regression analyses were conducted to identify factors related to hit-and-run and to identify factors related to the identification of the hit-and-run driver. Results indicate an increased risk of hit-and-run in the early morning, poor light conditions, and on the weekend. There may also be an association between the type of victim and the likelihood of the driver leaving and being identified. Results also indicate that certain driver characteristics, behavior, and driving history are associated with hit-and-run. Alcohol use and invalid license were among the leading driver factor associated with an increased risk of hit-and-run. Prevention efforts that address such issues could substantially reduce pedestrian fatalities as a result of hit-and-run. However, more information about this driver population may be necessary.     

Time-series intervention analysis of pedestrian countdown timer effects

Pedestrians account for 40–50% of traffic fatalities in large cities. Several previous studies based on relatively small samples have concluded that Pedestrian Countdown Timers (PCT) may reduce pedestrian crashes at signalized intersections, but other studies report no reduction. The purposes of the present article are to (1) describe a new methodology to evaluate the effectiveness of introducing PCT signals and (2) to present results of applying this methodology to pedestrian crash data collected in a large study carried out in Detroit, Michigan.     

Pedestrian crashes in Washington,DC and Baltimore

Police crash reports were obtained for pedestrian-motor vehicle crashes in Washington, DC (N = 852) and Baltimore (N = 1234) for the year 1998. Reports were coded using procedures developed and applied in these two cities during the 1970s, including the determination of pedestrian crash type, primary precipitating factor, and culpability. Results indicated substantial differences between crash patterns observed during the 1970s and those observed during 1998. Midblock dart-dash crashes, which typically involve a precipitating factor or critical error by a child pedestrian, decreased (from 37% to 15% in Washington). Across all crashes in both cities, the number of drivers who made a critical error leading to the crash was nearly equivalent to the number of pedestrians who made a critical error. Overall, pedestrians were slightly more likely to be judged culpable (50% vs. 39%). Turning vehicle crashes, which typically involve a driver's failure to grant a pedestrian the right of way at a signalized intersection, increased (from 9% to 25% in Washington). Countermeasures to reduce the number of pedestrians hit by turning vehicles are discussed.     

Driving behaviors and accident risk under lifetime license revocation

This study explored the driving behaviors and crash risk of 768 drivers who were under administrative lifetime driver's license revocation (ALLR). It was found that most of the ALLR offenders (83.2%) were still driving and only a few (16.8%) of them gave up driving completely. Of the offenders still driving, 67.6% experienced encountering a police roadside check, but were not detained or ticketed by the police. Within this group, 50.6% continued driving while encountering a police check, 18.0% of them made an immediate U-turn and 9.5% of them parked and exited their car. As to crash risk, 15.2% of the ALLR offenders had at least one crash experience after the ALLR had been imposed. The results of the logistic regression models showed that the offenders’ crash risk while under the ALLR was significantly correlated with their personal characteristics (personal income), penalty status (incarceration, civil compensation and the time elapsed since license revocation), annual distance driven, and needs for driving (working, commuting and driving kids). Low-income offenders were more inclined to have a crash while driving under the ALLR. Offenders penalized by being incarcerated or by paying a high civil compensation drove more carefully and were less of a crash risk under the ALLR. The results also showed there were no differences in crash risk under the ALLR between hit-and-run offences and drunk driving offences or for offenders with a professional license or an ordinary license. Generally, ALLR offenders drove somewhat more carefully and were less of a crash risk (4.3 crashes per million km driven) than legal licensed drivers (23.1 crashes per million km driven). Moreover, they seemed to drive more carefully than drivers who were under short-term license suspension/revocation which previous studies have found.