Crash Reduction Research Articles

Impact of COVID-19 pandemic on road safety in Tamil Nadu, India

This study uses structured literature mapping to review worldwide trends in traffic safety following the phenomenon of the COVID-19 pandemic. Motivated by dissimilar findings globally and a lack of evidence from emerging nations which have been significantly more affected by road traffic crashes, the study examines the impact of the pandemic-induced lockdown on road traffic deaths and injuries in Tamil Nadu, India. Using a holistic approach, methods such as ARIMA, Holt-Winters, Bayesian Structural Time Series, and Generalized Additive Model are employed for counterfactual prediction, to draw a causal inference of lockdown on traffic safety. In line with global studies, a substantial reduction in traffic crashes, injuries, and fatalities during lockdowns has been found. However, the comparison of relative differences shows that the number of grievous injuries reduced more than minor injuries, crashes, or fatalities. Furthermore, these relative differences were sustained even when metrics returned to normalcy in the post-lockdown phases. Further spatial stratification at two levels (cities and districts) shows that the macroscopic state-level trends are also broadly seen in the sub-units. This validates the consistency of trends across rural–urban differences and shows that, despite variations in the degree of enforcement of the lockdown within Chennai city, contrary to expectation, increased police presence did not have a differential impact on road crashes.

The AAA Approach to Crash Investigation Reform – The Perspective from Road Policing Practitioners

Professional road crash investigation, complemented by intelligent analysis and dynamic actions provide the foundation for road safety reform. However, to date, the real potential resulting from police investigative findings have not been fully realised due to the lack of streamlined connectivity from the crash scene to the reform process. Such deficiencies include inadequate investigations, inadequate data management, convoluted processes, system delays, inadequate analysis and limited immediate and mid-term actions which should be generated following thorough and efficient investigations. A review of processes across high, medium and low-income countries has identified a more effective approach to achieving results in road safety reform across all road safety disciplines. The simple AAA framework to ‘Acquire, Analyse and Action’ is presented as a contemporary model to ensure an evidence-based foundation drives road safety reform to identify root cause analysis locally, nationally and globally. This provides structure, discipline and purpose as well as technical skill and competence to achieve practical recommendations as preventative measures for crash reduction. A multi-disciplined expert review team to validate/assess/modify these recommendations in serious crashes ensures constructive countermeasures are prioritised and actioned. This facilitates a paradigm shift in thinking and analysis to achieve a continuous improvement process designed to reduce road trauma and save lives.

A COVID-19 Public Health Silver Lining? Reductions in Driving under the Influence Arrests and Crashes in Miami-Dade County

ABSTRACT The health crisis that began in early 2020 has generated a large amount of interest in the effect of COVID-19 on public health. The majority of this work has centered around trying to better understand how the virus spreads, where it spreads, who is at risk and when, in order to provide evidence-based guidance to the public, and stop the pandemic. The Centers for Disease Control has continued to report the largely somber findings; however, there are silver linings. The temporary reduction in daily global CO2 emissions was one of these, but there are others. In this case study on Miami-Dade County, Fl, a regression discontinuity model is used to highlight reductions in both drunk driving crashes and driving under the influence arrests. While we observed immediate reductions in both crashes and arrests as a result of the March 2020 lockdown, more importantly over the duration of the year since the lockdown we observed a staggering reduction of over 800 fewer driving under the influence arrests and almost 150 alcohol-related motor-vehicle crashes.

Severity, Spatial Pattern and Statistical Analysis of Road Traffic Crash Hot Spots in Ethiopia

The reduction of traffic crashes, as well as their socio-economic consequences, has captivated the attention of safety professionals and transportation agencies. The most important activity for an effective road safety practice is to identify hazardous roadway areas based on a spatial pattern analysis of crashes and an evaluation of crash spatial relations with neighboring areas and other relevant factors. For decades, safety researchers have adopted several techniques to analyze historical road traffic crash (RTC) information using the advanced GIS-based hot spot analysis. The objective of this study is to present a GIS technique for identifying crash hot spots based on spatial autocorrelation analysis using a four-year (2014–2017) crash data across Ethiopian regions, as well as zones and towns in the Oromia region. The study considered the corresponding severity values of RTCs for the analysis and ranking of crash hot spot areas. The spatial autocorrelation tool in ArcGIS 10.5 was used to analyze the spatial patterns of RTCs and then the Getis Ord Gi* statistics tool was used to identify high and low crash severity cluster zones. The results showed that the methods used in this analysis, which incorporated Moran’s I spatial autocorrelation of crash incidents, Getis Ord Gi* and crash severity index, proved to be a fruitful strategy for identifying and ranking crash hot spots. The identified crash hot spot areas are along the entrance to and exit from Addis Ababa, Ethiopia’s capital city, so the responsible bodies and traffic management agencies should give top priority attention and conduct a thorough study to reduce the socio-economic effect of RTCs.

Do everyday proactive policing activities reduce vehicle crashes? Examining a commonly held law enforcement belief using a novel method

Traffic accidents present a significant challenge to public safety and are a top priority for many law enforcement agencies in the United States. Empirical studies suggest that police agencies commonly engage in traffic enforcement activities to be proactive, spending much of their downtime patrolling areas with heightened risks for vehicle crashes. Despite the ongoing focus on traffic enforcement in daily police work, the impact of these efforts on traffic accidents remains unclear. The current study uses a Generalized Method of Moments (GMM) framework to examine everyday police proactive work and its impact on vehicle crashes at “hot spots” of collisions in a large suburban jurisdiction. Findings indicate that routine patrol levels and activities produce short-term reductions in crashes at the most serious crash hot spots but have less impact elsewhere. To generate a more sustained and optimal effect on traffic safety, everyday police proactivity needs to be more carefully calibrated in terms of its targeting, dosage, and types of activities.

A Comparison of Lane Marking Detection Quality and View Range between Daytime and Night-Time Conditions by Machine Vision

Lateral support systems in vehicles have a high potential for reduction of lane departure crashes. To profit from their full potential, such systems should function properly in adverse conditions. Literature indicates that their accuracy varies between day and night-time. However, detailed quantifications of the systems’ performance in these conditions are rare. The aim of this study is to investigate the differences in detection quality and view range of Mobileye 630 in dry daytime and night-time conditions. On-road tests on four rural road sections in Croatia were conducted. Wilcoxon signed-rank test was used to test the difference between the number of quality rankings while absolute average, average difference and standard deviation were used to analyse the view range. Also, a paired samples t-test was used to test the difference between conditions for each line on each road. The overall results confirm that a significant difference in lane detection quality view range exists between tested conditions. “Medium” and “high” detection confidence (quality level 3 and 2), increased by 5% and 8% during night-time compared to daytime while level 0 (“nothing detected”) decreased by 12%. The view range increased (almost 16% for middle line) during daytime compared to night-time. The findings of this study expand the existing knowledge and are valuable for research and development of machine-vision systems but also for road authorities to optimize the markings’ quality performance.

Estimating Safety Impacts of Adaptive Signal Control Technology Using a Full Bayesian Approach

Adaptive signal control technology (ASCT) is a traffic management strategy that optimizes signal timing based on real-time traffic demand. Although the primary intent of ASCT is to improve the operational performance of signalized intersections, the technology may also have substantial safety benefits. This study explored the potential safety benefits of the ASCT strategy deployed at signalized intersections in Florida, U.S. An observational before-after full Bayes (FB) approach with a comparison group was adopted to develop crash modification factors (CMFs) for total crashes, rear-end crashes, and specific crash severity levels (fatal plus injury [FI], and property damage only [PDO] crashes). The analysis was based on 20 intersections equipped with ASCT and their corresponding 40 comparison intersections without ASCT. The ASCT deployment was found to significantly reduce total crashes by 7.8% (CMF = 0.922), rear-end crashes by 8.7% (CMF = 0.913), and PDO crashes by 8.1% (CMF = 0.919). The 8.6% reduction in FI crashes (CMF = 0.914) was not significant at a 90% Bayesian credible interval. These findings provide researchers and practitioners with an effective means to quantify the safety benefits of the ASCT strategy and conduct economic appraisals of ASCT deployments.

Log truck crashes before and after weight limit increases in North Carolina and Virginia, USA

ABSTRACT Increasing timber transportation safety is essential to the timber harvesting and forest products industries. Log truck weight limits in the US South are lower than in other US regions. North Carolina and Virginia increased their gross vehicle weight limits for log trucks from 38,102 kg to 40,823 kg in 2012 and 2015, respectively. Log truck crash reports were collected from state authorities in North Carolina and Virginia for crashes occurring between 2009 and 2019. Log truck crash rates, contributing factors, crash locations, and vehicle condition were analyzed to identify opportunities to improve safety and evaluate the relationship between log truck crashes and changes in weight limits. Between 2009 and 2019, log truck crashes per million tonnes of timber harvested increased by 134% and 29% in North Carolina and Virginia, respectively. Crash rates were rising before the increases in weight limits and continued to rise afterward. Exceeding safe speed, improper turn, and failure to yield the right-of-way were common contributors to crashes in both states. Timber transportation safety may be improved through driver education, better fleet maintenance, and increased use of crash reduction technologies.

ROAD TRANSPORT CRASHES AND SOCIO-ECONOMIC INDICATORS: A CASE OF NIGERIA

The aim of this study is to provide basis for the understanding of transport crashes as affected by socio-economic indicators with a view to providing basis for road safety policies for transport management and control in Nigeria. The objectives were to (i) examine the trend of road transport crashes in Nigeria from 1960 to 2010, (ii) identify the socio-economic development indicators and incidences that are related to road transport crashes in Nigeria, (iii) examine the road transport safety measures aimed at reducing road transport crashes and (iv) assess the contributions and challenges of road safety related agencies in the reduction of road transport crashes. Except for annual life expectancy, other socio-economic development indicators had relationship with road transport crashes in Nigeria (R2 = 0,956, p = 0.000, P<0.05). The model of this study was defined as follows: RTC= 8047.7 + 0.041(GDP) - 0.000000812 (FDI) + 0.0006 (population) - 0.0005 (vehicle) + 0.199 (telecom) – 0.388 (road length) + 0.016 (wages) – 0.001 (goods by road). The road transport safety counter measures have reduced transport crashes by these percentages: use of seat belt (35 percent), standard speed limit signs (18 percent), speed limiters/governors (14.4 percent), use of child restraints (12.9 percent), issuance of standard licence (12 percent) and reflective pavement marking (7.7 percent). Insufficient funding (34 percent), political challenges/interferences (26 percent), lack of modern equipment and logistics (16 percent), poor training and retraining of road safety personnel (10 percent), and security challenges (8 percent) constituted the challenges of road transport crash related agencies in the reduction of road transport crashes. The study concluded that national socio-economic development indicators (Gross Domestic Product, Foreign Direct Investment, Population, Vehicle, Telecommunication, Wages, Road Length and Tonnage of Goods) have a significant relationship with road transport crashes except the annual life expectancy.

The Impact of COVID-19 Lockdown on Injuries in Saudi Arabia: Results From a Level-I Trauma Center.

Background: The COVID-19 pandemic has placed an enormous strain on global health. Due to precautionary measures, the epidemiology of health conditions may have been affected. Saudi Arabia imposed a lockdown order on March 25, 2020. This study investigated the impact of the pandemic lockdown on injuries in a level-I trauma center in King Abdulaziz Medical City, Riyadh, Saudi Arabia.Methods: This retrospective study identified all injured patients seeking emergency care during the lockdown period (March 25–June 21, 2020) and a similar period in two previous year (March 25–June 21) 2018 and 2019. The collected data included patients' demographics, injury types, mechanisms, and health outcomes.Results: Two hundred sixty nine injured patients sought emergency care during the lockdown, while 626 and 696 patients were treated in the same period of 2018 and 2019, respectively. There was a significant reduction in motor vehicle crashes (OR: 0.47; 95% CI: 0.31–0.73) and burns (OR: 0.24; 95% CI: 0.08–0.66), coupled with a significant increase in assault injuries (OR: 2.20; 95% CI: 1.30–3.74) in the lockdown period compared to 2019. Apart from the intensive care unit (ICU) admission and hospital length of stay, there were no differences between the two periods in the health outcomes. ICU admission was significantly reduced by 57% during the lockdown period (OR: 0.43; 95% CI: 0.22–0.83). Mechanisms of injuries were not significant predictors of deaths or ICU admission or both in the lockdown period.Conclusion: The COVID-19 lockdown had a clear impact on the volume and mechanisms of injuries. The findings highlight that injury risk factors are modifiable and emphasize the importance of public health measures for preventing injuries and the significance of maintaining trauma services capacity during pandemics.

Field effectiveness of general motors advanced driver assistance and headlighting systems

This study examined the field effectiveness of General Motors advanced driver assistance and headlighting systems. A total of 8,311,707 Model Year 2013–2019 vehicles were matched to police-reported crashes from 12 states. The quasi-induced exposure method was used to compare system-relevant and system-irrelevant (control) crash counts for equipped and unequipped vehicles. Logistic regression was used to adjust for ten covariates. Results indicated fusion/radar Automatic Emergency Braking, camera Automatic Emergency Braking, and Forward Collision Alert systems reduced rear-end striking crashes by 45%, 38%, and 20%, respectively. When restricting data to crashes in which someone in the General Motors striking vehicle was injured, these reductions were elevated to 59%, 54%, and 31%, respectively, providing evidence of additional crash mitigation benefits. Similarly, the Lane Keep Assist with Lane Departure Warning and Lane Departure Warning (alone) systems provided 12% and 10% reductions in lane departure crashes, respectively, with corresponding benefits in the injury analysis increasing to 19% and 18%, respectively. The Lane Change Alert with Side Blind Zone Alert system reduced lane change crashes by 16%. Reverse Automatic Braking, Rear Cross Traffic Alert, Rear Park Assist, and Rear Vision Camera (where each of these systems generally included all of the preceding systems) produced, respectively, an 82%, 55%, 36%, and 24% reduction in backing crashes. For Front Pedestrian Braking, a non-significant 14% reduction was observed for the limited set of available pedestrian crash cases. Intellibeam (auto high beam headlighting), High-Intensity Discharge headlights, and the combination of these two systems provided 26%, 11%, and 32% reductions (relative to halogen headlights) in a combined set of (unlighted) nighttime animal, pedestrian, and bicyclist crashes, respectively. These results provide widespread evidence of the substantial crash avoidance and injury reduction opportunities afforded by the production systems evaluated, as well as identify untapped system opportunities for moving toward a zero crashes vision.

Effect of Periodic Vehicle Inspection on Road Crashes and Injuries: A Systematic Review.

This systematic review was conducted to determine the effect of periodic motor vehicle inspections on road crashes and injuries, compared to less exposure to periodic inspections or no inspections. The Medline, Web of Science, and Scopus databases were used to search the literature. Ecological studies were specifically excluded. A reverse search of the results with these databases and of other identified narrative reviews was also performed. Of the 5065 unique references initially extracted, only six of them met the inclusion criteria and were selected for review: one experimental study, two cohort studies with an internal comparison group, two cohort studies without a comparison group, and one case–control study. Two authors independently extracted the information and assessed the quality of each study. Due to the heterogeneity of the designs and the intervention or comparison groups used, quantitative synthesis of the results was not attempted. Except for the case–control study, which showed a significant association between road crashes and the absence of a valid vehicle inspection certificate, the other studies showed either a small reduction in crash rates (around 9%), no association, or a higher crash rate in vehicles with more inspections. In all observational studies, the risk of residual confounding bias was significant and could have explained the results. Therefore, although the research reviewed here suggests that periodic inspection may be associated with a slight reduction in road crashes, the marked heterogeneity along with probable residual confounding in most reports prevented us from establishing causality for this association.

Study on Motorcycle Crash Cost in Bandung City

Crash cost is an important component for conducting economic analysis in selecting countermeasures for crash locations. It is used to convert the benefit of crash or fatality reduction into monetary terms. Many research on crash cost have been carried out in Indonesia. Most of the research utilized gross output/human capital approach. However, this approach has been widely criticized for not being able to describe the quality of life of crash casualties and the costs of pain, grief and suffering (i.e. human cost). The concept of Value of Statistical Life (VoSL) has been introduced by InDeV (2016) to calculate the human cost, which is assessed by using willingness to pay approach. To obtain a more reliable estimation of crash cost for Indonesia, it is necessary to conduct a study on crash cost involving motorcycles which incorporates the estimation of human cost. The VoSL is obtained by interviewing motorcycle users for willingness to pay with safety equipment. Based on the analysis, it is obtained that the value of statistical life (VoSL) for fatality in a road crash was estimated to be Rp.2.3 billion. The unit cost of fatal injury is Rp.3.08 billion, serious injury is Rp.333 million and slight injury is Rp.24.9 million. The unit cost of fatal crash on arterial roads is Rp.3.23 billion, serious crash is Rp.451 million and the slight crash is Rp.114 million. The unit cost of fatal crash on collector roads is Rp.3.16 billion, serious crashes is Rp.381 million and minor crash is Rp.69.4 million. The unit cost of fatal crash on local roads is Rp.3.09 billion, serious crash is Rp.338 million, and minor crash is Rp.29.8 million. Keywords: Motorcycle crash cost, gross output approach, human capital approach, willingness to pay approach

Evaluation of fog warning system on driving under heavy fog condition based on driving simulator

Purpose Heavy fog results in low visibility, which increases the probability and severity of traffic crashes, and fog warning system is conducive to the reduction of crashes by conveying warning messages to drivers. This paper aims at exploring the effects of dynamic message sign (DMS) of fog warning system on driver performance. Design/methodology/approach First, a testing platform was established based on driving simulator and driver performance data under DMS were collected. The experiment route was consisted of three different zones (i.e. warning zone, transition zone and heavy fog zone), and mean speed, mean acceleration, mean jerk in the whole zone, ending speed in the warning zone and transition zone, maximum deceleration rate and mean speed reduction proportion in the transition zone and heavy fog zone were selected. Next, the one-way analysis of variance was applied to test the significant difference between the metrics. Besides, drivers’ subjective perception was also considered. Findings The results indicated that DMS is beneficial to reduce speed before drivers enter the heavy fog zone. Besides, when drivers enter a heavy fog zone, DMS can reduce the tension of drivers and make drivers operate more smoothly. Originality/value This paper provides a comprehensive approach for evaluating the effectiveness of the warning system in adverse conditions based on the driving simulation test platform. The method can be extended to the evaluation of vehicle-to-infrastructure technology in other special scenarios.

Investigation of crashes at pedestrian hybrid beacons: Results of a large-scale study in Arizona

Introduction: The pedestrian hybrid beacon (PHB) is a traffic control device used at pedestrian crossings. A recent Arizona Department of Transportation research effort investigated changes in crashes for different severity levels and crash types (e.g., rear-end crashes) due to the PHB presence, as well as for crashes involving pedestrians and bicycles. Method: Two types of methodologies were used to evaluate the safety of PHBs: (a) an Empirical Bayes (EB) before-after study, and (b) a long-term cross-sectional observational study. For the EB before-after evaluation, the research team considered three reference groups: unsignalized intersections, signalized intersections, and both unsignalized and signalized intersections combined. Results: For the signalized and combined unsignalized and signalized intersection groups, all crash types considered showed statistically significant reductions in crashes (e.g., total crashes, fatal and injury crashes, rear-end crashes, fatal and injury rear-end crashes, angle crashes, fatal and injury angle crashes, pedestrian-related crashes, and fatal and injury pedestrian-related crashes). A cross-sectional study was conducted with a larger number of PHBs (186) to identify relationships between roadway characteristics and crashes at PHBs, especially with respect to the distance to an adjacent traffic control signal. The distance to an adjacent traffic signal was found to be significant only at the α = 0.1 level, and only for rear-end and fatal and injury rear-end crashes. Conclusions: This analysis represents the largest known study to date on the safety impacts of PHBs, along with a focus on how crossing and geometric characteristics affect crash patterns. The study showed the safety benefits of PHBs for both pedestrians and vehicles. Practical Applications: The findings from this study clearly support the installation of PHBs at midblock or intersection crossings, as well as at crossings on higher-speed roads.

Increasing the effectiveness of mobile speed cameras on rural roads in Victoria based on crash reductions from operations in Queensland

Mobile speed cameras on Victoria’s rural roads are not as effective as they could be due to the site selection criteria, the limited number of sites, and the visibility and predictability of their enforcement operations. Queensland’s overt mobile speed cameras achieve substantial crash reductions up to 4 km from rural camera sites due to site selection based only on crash history and randomised scheduling of operations to those sites. New sites in Victoria should be selected as in Queensland and camera visits should be randomly-scheduled. The Victorian Government’s announcement to increase mobile speed camera hours by 75% should take the form of at least 75% increase of rural sites. The new sites should be selected on the basis of a serious crash history within 2.5 km. Mobile speed cameras operated at these new rural sites could be expected to save 22.5 fatal crashes and 172 serious injury crashes per year.

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.

At what stages of licensing do graduated driver licensing systems reduce crashes? Example from Queensland, Australia

Evaluations of new graduated licensing systems (GLS) commonly examine pre-post young driver crash rates relative to another driver group. This comparison approach is important to account for other influences on crashes over time, but has limited ability to determine which GLS components are most effective and at what stage during the licensing process. We previously identified declines in young driver crashes in Queensland, Australia, following introduction of a new GLS in 2007. The objective of the current research was to conduct complementary modelling to identify at what points through the licensing process had particular GLS policies contributed to reductions. Crash trends were explored for learner and provisional drivers under the new GLS versus previous system for three time periods relative to the month of acquiring a provisional licence: the preceding learner period, the first month of provisional licensure (when crashes typically peak), and the overall provisional period. Interrupted time series analyses were conducted for the log ratio of crashes per 10,000 licensed (learner and provisional) drivers with the total number of licensed drivers as an offset. The greatest declines were found in the first month of licensure, with indications that a longer learner period, higher supervised driving hours, and a new provisional night-passenger restriction were key contributors to provisional crash reductions. There was also some indication that a restriction on all phone use reduced crashes during the learner period. We conclude that time series analysis focusing on licensing stage, rather than calendar time only, offers a complementary approach to analysing GLS effectiveness by better identifying where and how changes impact crashes.

Assessing the likelihood of secondary crashes on freeways with Adaptive Signal Control System deployed on alternate routes

Introduction: Reducing the likelihood of freeway secondary crashes will provide significant safety, operational and environmental benefits. This paper presents a method for assessing the likelihood of freeway secondary crashes with Adaptive Signal Control Systems (ASCS) deployed on alternate routes that are typically used by diverted freeway traffic to avoid any delay or congestion due to a freeway primary crash. Method: The method includes four steps: (1) identification of secondary crashes, (2) verification of alternate routes, (3) assessment of the likelihood of secondary crashes for freeways with ASCS deployed on alternate routes and non-ASCS (i.e. pre-timed, semi- or fully-actuated) alternate routes, and (4) investigation of unobserved heterogeneity of the likelihood of freeway secondary crashes. Four freeway sections (i.e., two with ASCS deployed on alternate routes and two non-ASCS alternate routes) in South Carolina are considered. Results and Conclusions: Findings from the logistic regression modeling reveal significant reduction in the likelihood of secondary crashes for one freeway section (i.e., Charleston I-26 E) with ASCS deployed on alternate route. Other factors such as rear-end crash, dark or limited light, peak period, and annual average daily traffic contribute to the likelihood of freeway secondary crashes. Furthermore, random-parameter logistic regression model results for Charleston I-26 E reveal that unobserved heterogeneity of ASCS effect exists across the observations and ASCS are associated with the reduction of the likelihood of freeway secondary crashes for 84% of the observations (i.e., primary crashes). Location of the primary crash on the freeway is observed to affect the benefit of ASCS toward freeway secondary crash reduction as the primary crash’s location determines how many upstream freeway vehicles will be able to take the alternate route. Practical Applications: Based on the findings, it is recommended that the South Carolina Department of Transportation (SCDOT) considers deploying ASCS on alternate routes parallel to freeway sections where high percentages of secondary crashes are found.

Road safety resource allocation using the cost-effectiveness approach; case study in Iran

Road safety resource allocation determines the extent to which the combined alternatives of remedial actions can be effective. In this study, an economic appraisal was fulfilled using a cost-effectiveness analysis approach considering the cost of implementing countermeasures and the reliable number of crash reductions. This study includes a case study to investigate the cost-effectiveness analysis approach to allocate resources in high-risk areas and to investigate the possibility of substituting this approach for cost–benefit analysis if no data regarding crash costs are available. Since both approaches have yielded similar results across a range of budgets, cost-effectiveness analysis can be substituted for cost–benefit analysis because, despite having several advantages, cost–benefit analysis needs to estimate the social and economic costs of crashes. In addition, the cost–benefit analysis approach considers crashes resulting in fatalities and crashes causing injury separately, and because the net benefit from reducing fatal crashes is far greater than for injury crashes, owing to the high costs of fatal crashes, this approach proposes more expensive countermeasures. It was shown that a cost-effectiveness analysis distributes the available limited budget almost equally across all sites and chooses cheaper measures. In this study, a reliable relationship is suggested in order to estimate the number of crash reductions considering all aspects.