Relevant Crash Research Articles

Investigating safety and cost-effectiveness of cable median barriers in Louisiana

Objectives Cable median barriers (CMBs) are installed on freeway medians to prevent cross-median crashes and reduce the severity of median-related crashes. Though CMBs are effective in preventing cross-median crashes, they are also known to increase the number of property damage–only (PDO) crashes. The higher frequency of PDO crashes could result in increased CMB maintenance and repair expenses. The aim of this study is to evaluate the safety impact and economic justification of CMBs in Louisiana. Methods Initially, a flowchart was developed using Louisiana crash data to identify targeted crashes, such as median-related and cross-median crashes. This was followed by a 3-year observational before-and-after crash analysis with an emphasis on head-on collisions and crashes involving large trucks. Using a 4-step improved prediction method, crash modification factors were then developed to quantitatively assess the impact of CMBs on crash outcomes, accounting for and adjusting to changes in the annual average daily traffic (AADT) and relevant crash frequencies before and after CMB implementation. Finally, an exhaustive benefit–cost analysis was conducted to determine the cost-effectiveness of CMBs. Results The results revealed that CMBs significantly reduced cross-median crashes of all severities. However, an increase in PDO crashes was observed in both total and median-related crashes. Large truck cross-median crashes and head-on collisions also decreased significantly after CMB implementation. Testing Level 4 (TL-4) CMBs were found to be more effective in preventing vehicles from crossing the median and in reducing crashes of higher severity levels. The benefit–cost ratios, calculated using economic crash unit costs for both total and targeted crashes, were greater than 1. Notably, the estimated benefit–cost ratios were considerably higher, demonstrating that CMBs are cost-effective countermeasures for enhancing traffic safety. Conclusion This study contributes to the understanding of CMB performance from both traffic safety and economic perspectives. The findings may assist transportation agencies in making decisions regarding the management of CMB systems. Based on the comprehensive analysis of CMBs on Louisiana freeways, this project has revealed that CMBs are an effective and economically justified crash countermeasure. Thus, further implementation of CMBs is recommended until better alternatives are available.

The effects of Electronic Stability Control (ESC) on fatal crash rates in the United States

Problem: Electronic Stability Control (ESC) is believed to be among the most efficient vehicle safety interventions with reported effects around 50% for fatal single and rollover crashes. However, such estimates have used sample data, which have not controlled for the possibilities of self-selection, behavioral adaptation, increased access to the technology by less safe drivers, and the calculation of effects on very specific categories of crashes. Effects of ESC in the population can therefore be expected to be smaller than is currently believed. Method: National U.S. data for fatal crashes, driving exposure and other control factors, and market penetration of ESC over 1991–2021 were used to calculate whether the trends in fatalities over time in crash rates for singles, rollovers, and fatal crashes in general matched projections from estimates of effectiveness. Results: It was found that downward trends in the relevant crash types were generally present before ESC was introduced, and that the trends thereafter were weaker. Although some trends were consistent with effects of ESC, they were markedly smaller than the projected ones, and could be explained by other factors such as the number of vehicles per capita. At best, the effect for rollovers could be up to two-thirds of previous estimates, no effect was detected for singles, while for all fatal crashes results depended upon the type of analysis performed. These results conflict with conclusions in all published ESC crash sample studies, which have compared vehicles with and without ESC. This discrepancy can be explained by methodological errors in the previous studies using induced exposure methods and self-selected samples. Practical applications: Traffic safety may not be as much improved by technological interventions as believed. Alternative approaches to traffic safety are needed, which do not rely on technology that interferes with driver behavior.

Goods movement, road safety, and spatial inequity: Evaluating freight-related crashes in low-income or minority neighborhoods

The significant growth in freight traffic and relevant crashes has aroused increasing concerns about road safety threats in local communities. We use data from the Minneapolis-St. Paul Metropolitan Area and examine the spatial relationship between freight-related crashes and neighborhoods with low-income and minority populations. We find that both household income and percentage of minority population are significantly correlated with the density of both freight-related crashes and freight-related crashes causing severe injuries and fatalities. The results indicate that freight-related crashes are subject to a spatial inequity problem. The findings underscore the importance of incorporating freight-related safety improvement within these low-income and minority neighborhoods.

Effectiveness of front crash prevention systems in reducing large truck real-world crash rates

Objective: Forward collision warning (FCW) and automatic emergency braking (AEB) have the potential to prevent or mitigate many large truck crashes. While these systems are known to be effective in passenger vehicles, less is known about their effectiveness in large trucks. The objective of this study was to estimate the effectiveness of these systems in reducing real-world crash rates of large trucks. Methods: Data on Class 8 trucks operating on limited-access highways during 2017–2019 were obtained from SmartDrive Systems. Detailed data on exposure measures and crash circumstances were extracted from video footage by both automated means and manual coding. Crash rates were compared by front crash prevention technology (FCW, AEB, neither), both for all police-reportable crashes overall and for relevant crash types. Results: FCW was associated with a statistically significant 22% reduction in the rate of police-reportable crashes per vehicle miles traveled, and a significant 44% reduction in the rear-end crash rate of large trucks. AEB also was associated with significant reductions—12% overall and 41% for rear-end crashes. Warnings were issued in 31% of rear-end crashes for FCW-equipped trucks. AEB intervened in 43% of rear-end crashes; about two thirds of these interventions involved autobrake activations. On average, speed was reduced by over half between the time of the intervention and impact for both systems. Observed reductions in same-direction sideswipe and roadway departure crashes per mile traveled were smaller in magnitude than those of rear-end crashes; these were consistent with other crash avoidance technologies suspected to be bundled with FCW/AEB in some cases, and very few front crash prevention interventions occurred in these types of crashes. Conclusions: FCW and AEB are effective countermeasures for crashes in which large trucks rear-end other vehicles. Large truck safety is expected to improve as new trucks are increasingly equipped with these systems. FCW has the advantage that some of these systems can be retrofitted to existing trucks, so benefits can be realized sooner and with less investment.

Safety effects of wet-weather pavement markings

While there has been increasing interest in wet-weather pavement markings due to their improved visibility and potential for enhancing road safety in wet-night conditions, there is a lack of research evaluating their safety effectiveness based on actual wet-night crash data. This paper presents the safety assessment of wet-weather pavement markings in the Atlanta District of the Texas Department of Transportation, conducted by two different evaluation approaches that are known to be rigorous and statistically defensible: Empirical-Bayes before-after analysis and full Bayes before-after analysis with comparison groups. The results from both approaches suggest that there are positive safety effects of wet-weather pavement markings for relevant crashes, providing evidence-based support for safety benefits of wet-weather markings.

Motorcycle Accidents — A New Head and Neck Safety Device for Riders

This paper is devoted to the design and first implementation of a new head and neck safety device (NHNS) for race of motorcycles. The system aims to mitigate the effects of crash forces acting along almost every direction with respect to the head. The system is composed by a helmet, linked to a jacket by means of a number of cables and a by a number of stop surfaces to limit both the flexion and extension of the neck. Stop surfaces are provided also to limit the lateral leaning of the head. Preliminary numerical simulations, performed by a simplified human model, and experimental tests, ran by using a Hybrid III dummy, show that the NHNS has the potential to actually reduce the neck damage in some relevant crash situations. The effect of the device is reducing the load acting on the passenger’s neck and maintaining the vertebrae rotations within the physiological limits.

Effects of lane departure warning on police-reported crash rates

ObjectiveTo evaluate the effects of lane departure warning (LDW) on single-vehicle, sideswipe, and head-on crashes. MethodPolice-reported data for the relevant crash types were obtained from 25 U.S. states for the years 2009–2015. Observed counts of crashes with fatalities, injuries, and of all severities for vehicles with LDW were compared with expected counts based on crash involvement rates for the same passenger vehicles without LDW, with exposure by vehicle series, model year, and lighting system standardized between groups. For relevant crashes of all severities and those with injuries, Poisson regression was used to estimate the benefits of LDW while also controlling for demographic variables; fatal crashes were too infrequent to be modeled. ResultsWithout accounting for driver demographics, vehicles with LDW had significantly lower involvement rates in crashes of all severities (18%), in those with injuries (24%), and in those with fatalities (86%). Adding controls for driver demographics in the Poisson regression reduced the estimated benefit of LDW only modestly in crashes of all severities (11%, p < 0.05) and in crashes with injuries (21%, p < 0.07). ConclusionsLane departure warning is preventing the crash types it is designed to address, even after controlling for driver demographics. Results suggest that thousands of lives each year could be saved if every passenger vehicle in the United States were equipped with a lane departure warning system that performed like the study systems. Practical applicationsPurchase of LDW should be encouraged, and, because drivers do not always keep the systems turned on, future efforts should focus on designing systems to encourage greater use and educating consumers about the benefits of using the systems.

Analysis of Fatal Traffic Crash-Reporting and Reporting-Arrival Time Intervals of Emergency Medical Services

Emergency Medical Services (EMS) play a vital role in the postcrash effort to reduce fatalities by providing first aid and transportation to medical facilities. This study aims to analyze the time required for crash reporting and EMS arrival in fatal traffic crashes and to identify relevant crash, roadway, environmental and zonal socio-economic factors. The time required for EMS reporting and arrivals were calculated by location type (urban or rural) and roadway functional classification using Florida data. Subsequently, a variety of duration models were estimated to reveal the contributing factors for crash-reporting and reporting-arrival intervals. Although about 90% of fatal crashes are reported to EMS within ten minutes in both urban and rural settings, EMS average reporting time in rural areas (4.5 min) is greater than that in urban areas (3 min). Moreover, freeways require longer time for EMS arrival (8.3 min) compared with conventional roadways (6.8 min). It was shown that the log-logistic and gamma models performed the best for crash-reporting and reporting-arrival intervals, respectively. The modeling results revealed that both EMS reporting and arrival times are related to the crash, roadway, environmental, and socio-economic factors. The key findings indicate that EMS reporting and arrival times differ significantly according to the urban or rural designation and road functional classification, and that they have statistically significant relationship with various factors. It is expected that the findings from this study can be used to develop effective and practical strategic plans to minimize EMS reporting and arrival times and, therefore, decrease the likelihood of fatalities.

Cost and benefit estimates of partially-automated vehicle collision avoidance technologies

Many light-duty vehicle crashes occur due to human error and distracted driving. Partially-automated crash avoidance features offer the potential to reduce the frequency and severity of vehicle crashes that occur due to distracted driving and/or human error by assisting in maintaining control of the vehicle or issuing alerts if a potentially dangerous situation is detected. This paper evaluates the benefits and costs of fleet-wide deployment of blind spot monitoring, lane departure warning, and forward collision warning crash avoidance systems within the US light-duty vehicle fleet. The three crash avoidance technologies could collectively prevent or reduce the severity of as many as 1.3 million U.S. crashes a year including 133,000 injury crashes and 10,100 fatal crashes. For this paper we made two estimates of potential benefits in the United States: (1) the upper bound fleet-wide technology diffusion benefits by assuming all relevant crashes are avoided and (2) the lower bound fleet-wide benefits of the three technologies based on observed insurance data. The latter represents a lower bound as technology is improved over time and cost reduced with scale economies and technology improvement. All three technologies could collectively provide a lower bound annual benefit of about $18 billion if equipped on all light-duty vehicles. With 2015 pricing of safety options, the total annual costs to equip all light-duty vehicles with the three technologies would be about $13 billion, resulting in an annual net benefit of about $4 billion or a $20 per vehicle net benefit. By assuming all relevant crashes are avoided, the total upper bound annual net benefit from all three technologies combined is about $202 billion or an $861 per vehicle net benefit, at current technology costs. The technologies we are exploring in this paper represent an early form of vehicle automation and a positive net benefit suggests the fleet-wide adoption of these technologies would be beneficial from an economic and social perspective.

Relevant factors for active pedestrian safety based on 100 real accident reconstructions

The enhancement of pedestrian safety to avoid traffic accidents represents a major challenge. This study allows a better understanding of the issues in pedestrian protection. It highlights the potential of in-depth accident studies for identifying relevant crash parameters in the pedestrian active safety. A computational simulation tool was developed to reconstruct 100 pedestrian real-world crashes. Two of them are detailed to illustrate the methodology.A description of the complete sample is then presented which highlights the major factors affecting the detection of the pedestrian. These main factors concern the travel and impact speed of the vehicle, the pedestrian trajectory and his walking speed, the scene configuration with obstacles, and the weather conditions. In particular, it has been shown that 1 s before the impact, only 30% of pedestrians are located in front of the car and 90% of them are less than 20 m from the front of the car.

Risk Factors Associated with Crash Severity on Low-Volume Rural Roads in Denmark

Safety on low-volume rural roads is drawing attention due to the high fatality and severe injury rates in comparison with high-volume roads and the increasing awareness of sustainable rural development among policy makers. This study analyzes the risk factors associated with crash severity on low-volume rural roads, including crash characteristics, driver attributes and behavior, vehicle type, road features, environmental conditions, distance from the nearest hospital, and zone rurality degree. The data consist of a set of crashes occurred on low-volume rural roads in Denmark between 2007 and 2011. The crashes were identified by map-matching the crash location to the geographic information system representing the national transport network and extracting the relevant crashes based on annual average traffic volumes. Injury severity was modeled by estimating a generalized ordered logit model due to its advantage in accommodating the ordered-response nature of severity while relaxing the proportional odds assumption. Model estimates and pseudoelasticities show that aggravated crash injury severity is significantly associated with (1) alcohol and failure to wear seatbelts, (2) involvement of vulnerable road users (i.e., pedestrians, cyclists and motorcyclists), (3) involvement of heavy vehicles, (4) speed limits of 80–90 km/h, (5) longer distance to the nearest hospital, and (6) peripheral rural regions.

Predictive Braking Assistance System for Intersection Safety Based on Risk Potential

This paper describes the assessment of a predictive braking assistance system by using a driving simulator which can reconstruct near-miss incident scenario relevant to pedestrians. A braking assistance system algorithm for collision avoidance is designed based on pedestrian motion prediction and risk potential. A virtual spring connected between the vehicle and the pedestrian is used to determine the potential field. The feasibility of the proposed algorithm is examined by experiments using the driving simulator and a comparison with actual expert driving data. Near-miss incident data relevant to pedestrians in intersections collected by image-captured drive recorders are analyzed to get the basic parameters of pedestrian relevant crash scenario model. The effectiveness of the proposed system is verified by driving simulator experiments.

Heavy trucks, conspicuity treatment, and the decline of collision risk in darkness

IntroductionThe influence of amendments to Federal Motor Vehicle Safety Standard (FMVSS) 108, requiring conspicuity treatments on heavy tractors and trailers, was determined in analyses of the odds of fatal collisions in darkness. MethodComparisons were made between crashes in which conspicuity treatment was likely relevant, and those in which it was likely irrelevant. ResultsOver 23years, the odds that a fatal collision involving a heavy truck occurred in darkness declined by 58% among relevant crashes, while little decline was observed for irrelevant crashes. Disaggregation into crash types revealed the largest declines occurred in fatal rear-end and angle collisions. A parallel analysis of light vehicles also found declines but no differences among crash type. Similar trends were also observed for nonfatal rear end collisions. ConclusionThe results suggest that detection failure may have contributed to the risk of striking a tractor-semitrailer in darkness, and that conspicuity treatments have reduced this risk. Impact on IndustryConspicuity treatments appear to reduce risk of collision into heavy trucks in darkness. It is likely that this benefit would also extend to other vehicles that are not included in the FMVSS 108 regulation (e.g., buses, single unit trucks, recreational vehicles), although many are so equipped, regardless of the regulation.

Nonconformities in Real-World Fatal Crashes— Electronic Stability Control and Seat Belt Reminders

Objective: Many new safety systems are entering the market. Vision Zero is a safety strategy aiming at the elimination of fatalities and impairing injuries by the use of a holistic model for safe traffic to develop a safe system. The aim of this article is to analyze fatalities in modern cars with respect to the Vision Zero model with special respect to electronic stability control (ESC) systems and modern seat belt reminders (SBRs). The model is used to identify and understand cases where cars with ESC systems lost control and where occupants were unbelted in a seat with seat belt reminders under normal driving conditions. Methods: The model for safe traffic was used to analyze in-depth studies of fatal crashes with respect to seat belt use and loss of control. Vehicles from 2003 and later in crashes from January 2004 to mid-2010 were analyzed. The data were analyzed case by case. Cars that were equipped with ESC systems and lost control and occupants not using the seat belt in a seat with a seat belt reminder were considered as nonconformities. A total of 138 fatal crashes involving 152 fatally injured occupants were analyzed. Results: Cars with ESC systems had fewer loss-of-control–relevant cases than cars without ESC systems. Thirteen percent of the ESC-equipped vehicles had loss-of-control–relevant crashes and 36 percent of the cars without ESC systems had loss-of-control–relevant crashes. The analysis indicates that only one car of the 9 equipped with ESC that lost control did it on a road surface with relevant friction when driving within the speed restriction of the road. In seats with seat belt reminders that are in accordance with the European New Car Assessment Programme's (Euro NCAP) protocol, 93 percent of the occupants were using a seat belt. In seats without reminders this number was 74 percent. Conclusions: This study shows that ESC systems result in a very significant reduction in fatal crashes, especially under normal driving conditions. Under extreme driving conditions such as speeding or extremely low friction (snow or on the side of the road), ESC systems can fail in keeping the car under control. Seat belt reminders result in higher seat belt use rates but the level of unbelted occupants is higher than roadside studies have indicated. The holistic Vision Zero approach helped in the analysis by identifying nonconformities and putting these into the safe systems perspective.

Extension of the Honda-DRI “Safety Impact Methodology” (SIM) for the NHTSA Advanced Crash Avoidance Technology (ACAT) II Program and Application to the Evaluation of a Pre-Production Head-On Crash Avoidance Assist System - Progress Report

This paper reports on the interim progress of the Honda-DRI ACAT-II program initiated by the National Highway Traffic Safety Administration (NHTSA). The objectives of the ACAT-II program were further development of a formalized Safety Impact Methodology (SIM) for estimating the capability of advanced technology applications installed in vehicles to address specific types of motor vehicle crashes, and to evaluate driver acceptance of the technologies. This particular ACAT study extended earlier work by Honda and DRI in the NHTSA ACAT-I program by extending the SIM so as to be able to analyze head-on crashes more completely, and by using the extended SIM to evaluate of a preproduction version of a Honda Head-on Crash Avoidance Assist System (HCAAS). More than 25 substantial SIM extensions and refinements were implemented, including: updated and extended FARS and NASS database extractions; improving the accident reconstruction process for NASS/CDS cases and developing a new special purpose reconstruction algorithm applicable to head-on cases with low lateral acceleration drifts; extending the driver-vehicle- ACAT environment simulation to include a post-conflict recovery phase; and further automating the overall safety benefits evaluation steps. The extended SIM and results from objective tests were used to evaluate the safety impact of Honda's pre-production H-CAAS based on a large number of simulations of a sample of reconstructed real-world head-on crashes. The effectiveness of the H-CAAS in reducing the number of two-vehicle Same Trafficway, Opposite Direction crashes (including non-H-CAAS technology relevant crashes) and fatalities if the H-CAAS were installed on one of the crash involved vehicles were estimated based on simulation results. The overall benefits of the H-CAAS, in terms of reduction in number of crashes and fatalities, when projected to the US level were also determined. Overall, this ACAT-II program was successful in extending a methodology that can be used to estimate the safety benefits and driver acceptance of frontal crash avoidance and mitigation countermeasures. Language: en

Strengthening Driver Licensing Systems for Teenaged Drivers

GRADUATED DRIVER LICENSING PROGRAMS ARE designed to reduce crashes involving teenagers by delaying full licensure while allowing beginners to obtain initial driving experience under lower-risk conditions. Graduated driver licensing strengthens the traditional learner phase by adding elements such as certification of a minimum number of practice driving hours and a minimum learner’s permit holding period. It also adds an intermediate license between the learner phase and full licensure that restricts unsupervised driving in risky situations (eg, driving at night and transporting teenaged passengers). Although Florida is credited with having enacted the first graduated driver licensing program in the United States in 1996, the benefits of delaying licensure and restricting nighttime driving were demonstrated in the 1980s and early 1990s. Currently, all states and the District of Columbia have enacted some form of graduated driver licensing. As states adopted graduated driver licensing, per capita rates of fatal crashes among teenaged drivers decreased substantially. Between 1996 and 2009, there were large declines inthesecrashrates for15-year-olds(69%),16-year-olds(68%), and 17-year-olds (53%) (the ages directly affected by graduated driver licensing) and smaller but substantial declines for 18-year-olds(43%)and19-year-olds(39%). Thesedecreases in rates of fatal crashes were greater than declines among 30to59-year-olddrivers (33%during thisperiod).However, in 2008 the rate of police-reported crashes per mile driven for 16to 19-year-olds was 4 times the rate for older drivers, and their rate of fatal crashes was twice that for older drivers. In jurisdictions that have adopted elements of graduated driver licensing, overall crash rates among young teenagers have declined by 20% to 40%. Restrictions on nighttime driving and transporting teenaged passengers have proven effective in reducing relevant crashes. National studies have found that 3-stage graduated driver licensing programs (with learner’s, intermediate, and full licensure stages) and laws that impose more licensing components, or more restrictive components, are associated with decreases in per capita rates of fatal crashes or fatalities among young teenagers. The study by Masten and colleagues in this issue of JAMA adds new evidence on this important topic and reports a 26% lower per capita rate of fatal crash incidence for 16-yearolds associated with stronger graduated driver licensing programs. Masten et al also report a 12% higher rate of fatal crash incidence for 18-year-olds and a nonsignificant, slightly lower rate for 16to 19-year-olds combined. Implementation of the 3-stage concept of graduated driver licensing has differed among states, and licensing practices vary widely. The Insurance Institute for Highway Safety (IIHS) evaluated the strength of state licensing systems, rating them as good, fair, marginal, or poor. Criteria include the strength of the learner and intermediate phases (entry age and duration for both phases, a practice driving requirement in the learner phase, and strength of restrictions on nighttime driving and allowable passengers in the intermediate stage). The learner’s permit and licensing ages are not inherent to a staged-in approach to licensure but are fundamental aspects of licensing laws and may be affected by graduated driver licensing provisions. Therefore, a comprehensive approach is needed to understand fully how licensing laws affect safety. The findings reported by Masten et al differ from those reported in 2 other studies using the IIHS ratings to measure the strength of licensing laws. McCartt et al evaluated the association between stronger licensing laws and teenagers’ per capita rates of fatal crashes. That study found a strong association between better IIHS ratings and lower rates of fatal crashes among 15to 17-year-olds. Associations between the IIHS ratings and rates of fatal crashes for 18and 19-year-olds were weaker and generally not statistically significant. Compared with laws rated poor by the IIHS, those rated marginal, fair, or good were associated with a significantly lower rate of fatal crashes for 15to 19-year-olds combined, including a 16% lower rate for laws rated good. In another report, Trempel evaluated the association between stronger licensing laws and the rates of insurance collision claims per insured vehicle year; only licensed drivers are insured, and collision claims primarily involve lowseverity crashes. There was a strong association between better IIHS ratings and lower collision claim rates among 16

Comparison of Severity of Motorcyclist Injury by Crash Types

The purpose of this study was to examine statewide motorcycle crash data from the state of Ohio to identify those factors most strongly associated with the level of injury sustained by motorcyclists involved in crashes. The year 2009 marked the first time since 1997 that Ohio experienced fewer motorcycle fatalities than in the previous year; this result was consistent with national trends over this same period. Since anecdotal evidence suggested that much of this result was due to decreases in motorcycle travel, an investigation of rider, crash, and environmental factors that influenced injury severity was an important step toward sustaining this reduction. The effects of such factors in various types of motorcycle crashes were compared. Multinomial logit models were developed for single-vehicle and multivehicle motorcycle crashes at both intersection and nonintersection locations. The results showed that the impacts of relevant crash factors varied by crash type and location and that severe injuries were more likely when high speed or alcohol was involved. Collisions with fixed objects and high-impact crashes, such as angle and head-on collisions, also produced dramatic increases in injury severity. Helmet use continued to provide the most promising means of reducing severe and fatal injuries in all types of crashes. Helmet use was found to reduce the likelihood of injury by 34.4% in single-vehicle crashes and between 12.4% and 14.1% in multivehicle crashes.

A framework for estimating the safety effects of roadway lighting at intersections

National- and state-level guidance documents conclusively state that fixed lighting improves intersection safety. The sentiment is consistent with other design and safety manuals and is supported by a series of consistent safety findings; however, most published lighting-safety research is focused on rural, stop-controlled intersections and is limited by several methodological issues. The relationship between safety and intersection lighting at rural, signalized and urban locations is not as well documented. Methodological advancements in highway safety analysis justify new estimations of the safety effects of intersection lighting. This paper describes a proposed framework to estimate the safety effects of fixed lighting at a variety of intersection types and locations. Several key issues are explored including availability of relevant crash, lighting, and roadway inventory data; relevant data element structures; proposed analysis taxonomies to assess lighting-safety effects within and across different intersection classifications; specification and estimation of models to estimate expected crash frequencies during day and night; techniques to interpret model parameters, including variable elasticity; and tests of model transferability across states. A sample framework execution using Minnesota intersection data is provided. Results indicate a much lower overall safety benefit from lighting than published studies, but are consistent with estimates included in Highway Safety Manual research.

Results of a Precrash Application Based on Laser Scanner and Short-Range Radars

In this paper, we present a vehicle safety application based on data gathered by a laser scanner and two short-range radars that recognize unavoidable collisions with stationary objects before they take place to trigger restraint systems. Two different software modules that perform the processing of raw data and deliver a description of the vehicle's environment are compared. A comprehensive experimental evaluation based on relevant crash and noncrash scenarios is presented.

Benefits and Costs of Ultraviolet Fluorescent Lighting

Ultraviolet (UVA) headlights are potentially a cost-effective way of reducing nighttime motor vehicle crashes and pedestrian crashes. A field study comparing UVA headlights to standard low beam headlights found significant improvements in detection and recognition distances for pedestrian scenarios, ranging from 34% to 117%. A cost analysis of using UVA headlights, along with fluorescent roadway paint, found that a 19.5% reduction in nighttime motor vehicle crashes involving pedestrians or pedal-cyclists will pay for the additional UVA headlight costs if headlights cost $100. Alternatively, given the same assumption, a 5.5% reduction in all relevant nighttime crashes will pay for the additional costs of UVA headlights and fluorescent highway paint combined. If the increased detection and recognition distances resulting from using UVA-fluorescent technology observed in this field study moderately reduce relevant crashes, the benefit cost ratios will exceed 1.0. Thus, the UVA-flourescent technology is potentially cost-effective and merits further consideration.