Estimating the human recovery costs of seriously injured road crash casualties

Road crashes result in substantial trauma and costs to societies around the world. Robust costing methods are an important tool to estimate costs associated with road trauma, and are key inputs into policy development and cost–benefit analysis for road safety programmes and infrastructure projects. With an expanding focus on seriously injured road crash casualties, in addition to the long standing focus on fatalities, methods for costing seriously injured casualties are becoming increasingly important. Some road safety agencies are defining a seriously injured casualty as an individual that was admitted to hospital following a road crash, and as a result, hospital separation data provide substantial potential for estimating the costs associated with seriously injured road crash casualties. The aim of this study is to establish techniques for estimating the human recovery costs of (non-fatal) seriously injured road crash casualties directly from hospital separation data. An individuals’ road crash-related hospitalisation record and their personal injury insurance claim were linked for road crashes that occurred in New South Wales, Australia. These records provided the means for estimating all of the costs to the casualty directly related to their recovery from their injuries. A total of 10,897 seriously injured road crash casualties were identified and four methods for estimating their recovery costs were examined, using either unit record or aggregated hospital separation data. The methods are shown to provide robust techniques for estimating the human recovery costs of seriously injured road crash casualties, that may prove useful for identifying, implementing and evaluating safety programmes intended to reduce the incidence of road crash-related serious injuries.     

Crash costs in the United States by crash geometry

MAIN OBJECTIVES: This study was conducted to estimate the costs per crash for three police-coded crash severity groupings within 16 selected crash geometry types and within two speed limit categories (or=50 mph). METHODS: We merged previously developed costs per victim by abbreviated injury scale (AIS) score into U.S. crash data files that scored injuries in both the AIS and police-coded severity scales to estimate injury costs, then aggregated the estimates into costs per crash by maximum injury severity. RESULTS: The most costly crashes were non-intersection fatal/disabling injury crashes on a road with a speed limit of 50 miles per hour or higher where multiple vehicles crashed head-on or a single vehicle struck a human (over 1.69 US dollars and 1.16 million US dollars per crash, respectively). The annual cost of police-reported run-off-road collisions, which include both rollovers and object impacts, represented 34% of total costs. CONCLUSIONS: This paper provides cost estimates useful for evaluating roadway countermeasures and for designing vehicles to minimize crash harm. It gives unit costs of crashes by type in the coding system used by the police. The costs are in an appropriate form for economic analysis of countermeasures addressing locally defined problems identified by analyzing police crash reports.     

The crash reduction effectiveness of a network-wide traffic police deployment system

Random Road Watch (RRW) is a traffic policing program in operation in Queensland, Australia. It differs from conventional traffic policing in that an explicit resource management technique is used which randomly schedules low levels of police enforcement in a manner intended to provide long-term, widespread coverage of a road network and hence maximise road safety benefits. Implementation of the program studied in Queensland covered 55% of total crashes within the state. This study aimed to measure the crash effects of the RRW program in Queensland. A quasi-experimental study design was used for the evaluation incorporating Poisson regression statistical analysis techniques. Analysis of the effects of the Queensland RRW program on crash frequency has shown the program to be effective overall. Estimated program effects were largest on fatal crashes, with an estimated reduction of 31%. Estimated aggregate program crash effects reduced with crash severity and increased with time after program introduction. Crash reductions in the third year after program introduction translated into savings, at state level, of some 12% of the state's crashes of all severities and some 15% of the state's fatal road crashes. Overall, the program produced a significant 11% reduction in total crashes in areas outside of metropolitan Brisbane. The opportunity-cost benefit/cost ratio for the program was estimated to be 55:1.     

Evaluating safety effectiveness of surface treatment at signalised intersections: a before and after study

In a metropolitan region of Melbourne, Australia, 136 signalised intersections were identified to have been resurfaced with asphalt over the period 2005–2010. In this study, the safety effectiveness of surface treatment was evaluated using Empirical Bayes (EB) approach to account for regression to the mean bias and traffic volume change through using safety performance function (SPF). Safety effects were estimated for total casualty, high severity (fatality and serious injury) and other injury crashes. For conducting EB method a reference group was selected with similar traffic volumes and site characteristics to the treated sites. Negative Binomial regression was applied to develop SPFs that were used to predict the expected number of crashes at the treated sites. The results of EB approach revealed that the treatment effect was found to be significant at 95% confidence level for all crash severity levels. The evaluation results also showed that total casualty crashes were reduced by 21.3% with a standard error of 3.13% and high severity (fatality and serious injury) crashes were reduced by 15.3% with a standard error of 5.56%. Pavement surface treatment was found to reduce other injury crashes by 21.4% with a standard error of 3.75%.     

Quantifying the safety effects of pavement friction improvements – results from a large-scale study

It is fairly well understood that there is link between pavement friction and safety, or more specifically, the probability of wet-weather skidding crashes. However, robust knowledge on the comparative quantitative effects on safety for specific treatments that improve pavement friction, which can assist pavement engineers in economically justifying and prioritising treatments, is sparse. The large-scale study on which this paper is based aimed to firm up this knowledge for a variety of low-cost treatments and road classes, using state-of-the-art methodology and substantial, high-quality data-sets. This was a retrospective study for pavement safety performance, looking back at crash data before and after treatments was implemented. Both flexible and rigid pavement treatments were analysed and crash modification factors were estimated for several target crash types and road classes. The majority of the friction improvement treatments considered under this effort are typically used for pavement preservation or minor rehabilitation purposes. Although pavement engineers recognise that these treatments generally improve safety, they are not typically installed by highway agencies explicitly for safety improvement objectives. The combined results for most treatment types confirmed nevertheless the safety benefits for wet-road crashes, with a few exceptions. For dry road crashes, there was some evidence of the deleterious effects of speed adaptation to new surfaces in that crashes increased for a few treatments on some road types.     

Social costs of road crashes: An international analysis

This paper provides an international overview of the most recent estimates of the social costs of road crashes: total costs, value per casualty and breakdown in cost components. The analysis is based on publications about the national costs of road crashes of 17 countries, of which ten high income countries (HICs) and seven low and middle income countries (LMICs). Costs are expressed as a proportion of the gross domestic product (GDP). Differences between countries are described and explained. These are partly a consequence of differences in the road safety level, but there are also methodological explanations. Countries may or may not correct for underreporting of road crashes, they may or may not use the internationally recommended willingness to pay (WTP)-method for estimating human costs, and there are methodological differences regarding the calculation of some other cost components.The analysis shows that the social costs of road crashes in HICs range from 0.5% to 6.0% of the GDP with an average of 2.7%. Excluding countries that do not use a WTP- method for estimating human costs and countries that do not correct for underreporting, results in average costs of 3.3% of GDP. For LMICs that do correct for underreporting the share in GDP ranges from 1.1% to 2.9%. However, none of the LMICs included has performed a WTP study of the human costs.A major part of the costs is related to injuries: an average share of 50% for both HICs and LMICs. The average share of fatalities in the costs is 23% and 30% respectively. Prevention of injuries is thus important to bring down the socio-economic burden of road crashes.The paper shows that there are methodological differences between countries regarding cost components that are taken into account and regarding the methods used to estimate specific cost components. In order to be able to make sound comparisons of the costs of road crashes across countries, (further) harmonization of cost studies is recommended. This can be achieved by updating and improving international guidelines and applying them in future cost studies. The information regarding some cost components, particularly human costs and property damage, is poor and more research into these cost components is recommended.     

Costs of large truck-involved crashes in the United States

This study provides the estimates of the costs of highway crashes involving large trucks by type of truck involved. These costs represent the present value of all costs over the victims' expected life span that result from a crash. They include medically related costs, emergency services costs, property damage costs, lost productivity, and the monetized value of the pain, suffering, and lost quality of life that a family experiences because of death or injury. Based on the latest data available, the estimated cost of police-reported crashes involving trucks with a gross weight rating of more than 10,000 pounds averaged US$ 59,153 (in 2000 dollars). Multiple combination trucks had the highest cost per crash (US$ 88,483). The crash costs per 1000 truck miles however, were US$ 157 for single unit trucks, US$ 131 for single combination trucks, and US$ 63 for multiple combinations.     

Comparison of empirical Bayes and full Bayes approaches for before-after road safety evaluations

The empirical Bayes (EB) approach has now gained wide acceptance among researchers as the much preferred one for the before-after evaluation of road safety treatments. In this approach, the before period crash experience at treated sites is used in conjunction with a crash prediction model for untreated reference sites to estimate the expected number of crashes that would have occurred without treatment. This estimate is compared to the count of crashes observed after treatment to evaluate the effect of the treatment. This procedure accounts for regression-to-the-mean effects that result from the natural tendency to select for treatment those sites with high observed crash frequencies. Of late, a fully Bayesian (FB) approach has been suggested as a useful, though complex alternative to the empirical Bayes approach in that it is believed to require less data for untreated reference sites, it better accounts for uncertainty in data used, and it provides more detailed causal inferences and more flexibility in selecting crash count distributions. This paper adds to the literature on comparing the two Bayesian approaches through empirical applications. The main application is an evaluation of the conversion of road segments from a four-lane to a three-lane cross-section with two-way left-turn lanes (also known as road diets). For completeness, the paper also summarizes the results of an earlier application pertaining to the evaluation of conversion of rural intersections from unsignalized to signalized control. For both applications, the estimated safety effects from the two approaches are comparable.     

Crash costs and safety investment

Injury crashes cost society more than $34 billion annually. Expending up to $2.3 million to prevent one fatal crash appears to be rational public policy, although the crash costs society only $500,000. Prevention of severe, nonfatal head and spinal cord injuries warrants even larger expenditures. The estimated rational investment to prevent an average nonfatal injury crash is $22,000, while society's cost is $8,000. Rational investment levels for increased safety are estimated by summing the amount individuals typically pay for small increases in their safety and the cost the rest of society bears when someone is killed or injured, including transfer payments.     

Driver inattention and driver distraction in serious casualty crashes: Data from the Australian National Crash In-depth Study

Driver inattention and driver distraction represent a major problem in road safety. Although both are believed to contribute to increased crash risk, there is currently limited reliable information on their role in crashes. The current study used in-depth data from the Australian National Crash In-depth Study to investigate the role of driver distraction and inattention in serious casualty crashes. The sample included 856 crashes from 2000 to 2011, in which at least one party was admitted to hospital due to crash-related injuries. Crashes were coded using a taxonomy of driver inattention that delineates five inattention subtypes: restricted attention, misprioritised attention, neglected attention, cursory attention, and diverted attention (distraction). Approximately 45% of crashes could not be coded due to insufficient information while in an additional 15% the participant indicated the “other driver was at fault” without specifying whether inattention was involved. Of the 340 remaining cases, most showed evidence of driver inattention (57.6%) or possible inattention (5.9%). The most common subtypes of inattention were restricted attention, primarily due to intoxication and/or fatigue, and diverted attention or distraction. The most common types of distraction involved voluntary, non-driving related distractions originating within the vehicle, such as passenger interactions. The current study indicates that a majority of serious injury crashes involve driver inattention. Most forms of inattention and distraction observed are preventable. This study demonstrates the feasibility of using in-depth crash data to investigate driver inattention in casualty crashes.     

How similar are two-unit bicycle and motorcycle crashes?

This paper explores the similarities and differences between bicycle and motorcycle crashes with other motor vehicles. If similar treatments can be effective for both bicycle and motorcycle crashes, then greater benefits in terms of crash costs saved may be possible for the same investment in treatments. To reduce the biases associated with under-reporting of these crashes to police, property damage and minor injury crashes were excluded. The most common crash type for both bicycles (31.1%) and motorcycles (24.5%) was intersection from adjacent approaches. Drivers of other vehicles were coded most at fault in the majority of two-unit bicycle (57.0%) and motorcycle crashes (62.7%). The crash types, patterns of fault and factors affecting fault were generally similar for bicycle and motorcycle crashes. This confirms the need to combat the factors contributing to failure of other drivers to yield right of way to two-wheelers, and suggest that some of these actions should prove beneficial to the safety of both motorized and non-motorized two-wheelers. In contrast, child bicyclists were more often at fault, particularly in crashes involving a vehicle leaving the driveway or footpath. The greater reporting of violations by riders and drivers in motorcycle crashes also deserves further investigation.     

Investigation of pedestrian crashes on two-way two-lane rural roads in Ethiopia

Understanding pedestrian crash causes and contributing factors in developing countries is critically important as they account for about 55% of all traffic crashes. Not surprisingly, considerable attention in the literature has been paid to road traffic crash prediction models and methodologies in developing countries of late. Despite this interest, there are significant challenges confronting safety managers in developing countries. For example, in spite of the prominence of pedestrian crashes occurring on two-way two-lane rural roads, it has proven difficult to develop pedestrian crash prediction models due to a lack of both traffic and pedestrian exposure data. This general lack of available data has further hampered identification of pedestrian crash causes and subsequent estimation of pedestrian safety performance functions. The challenges are similar across developing nations, where little is known about the relationship between pedestrian crashes, traffic flow, and road environment variables on rural two-way roads, and where unique predictor variables may be needed to capture the unique crash risk circumstances. This paper describes pedestrian crash safety performance functions for two-way two-lane rural roads in Ethiopia as a function of traffic flow, pedestrian flows, and road geometry characteristics. In particular, random parameter negative binomial model was used to investigate pedestrian crashes. The models and their interpretations make important contributions to road crash analysis and prevention in developing countries. They also assist in the identification of the contributing factors to pedestrian crashes, with the intent to identify potential design and operational improvements.     

The impact of alcohol and road traffic policies on crash rates in Botswana, 2004–2011: A time-series analysis

In Botswana, increased development and motorization have brought increased road traffic-related death rates. Between 1981 and 2001, the road traffic-related death rate in Botswana more than tripled. The country has taken several steps over the last several years to address the growing burden of road traffic crashes and particularly to address the burden of alcohol-related crashes. This study examines the impact of the implementation of alcohol and road safety-related policies on crash rates, including overall crash rates, fatal crash rates, and single-vehicle nighttime fatal (SVNF) crash rates, in Botswana from 2004 to 2011. The overall crash rate declined significantly in June 2009 and June 2010, such that the overall crash rate from June 2010 to December 2011 was 22% lower than the overall crash rate from January 2004 to May 2009. Additionally, there were significant declines in average fatal crash and SVNF crash rates in early 2010. Botswana's recent crash rate reductions occurred during a time when aggressive policies and other activities (e.g., education, enforcement) were implemented to reduce alcohol consumption and improve road safety. While it is unclear which of the policies or activities contributed to these declines and to what extent, these reductions are likely the result of several, combined efforts.     

Safety impacts of platform tram stops on pedestrians in mixed traffic operation: A comparison group before–after crash study

Tram stops in mixed traffic environments present a variety of safety, accessibility and transport efficiency challenges. In Melbourne, Australia the hundred year-old electric tram system is progressively being modernized to improve passenger accessibility. Platform stops, incorporating raised platforms for level entry into low floor trams, are being retro-fitted system-wide to replace older design stops. The aim of this study was to investigate the safety impacts of platform stops over older design stops (i.e. Melbourne safety zone tram stops) on pedestrians in the context of mixed traffic tram operation in Melbourne, using an advanced before–after crash analysis approach, the comparison group (CG) method. The CG method evaluates safety impacts by taking into account the general trends in safety and the unobserved factors at treatment and comparison sites that can alter the outcomes of a simple before–after analysis. The results showed that pedestrian-involved all injury crashes reduced by 43% after platform stop installation. This paper also explores a concern that the conventional CG method might underestimate safety impacts as a result of large differences in passenger stop use between treatment and comparison sites, suggesting differences in crash risk exposure. To adjust for this, a modified analysis explored crash rates (crash counts per 10,000 stop passengers) for each site. The adjusted results suggested greater reductions in pedestrian-involved crashes after platform stop installation: an 81% reduction in pedestrian-involved all injury crashes and 86% reduction in pedestrian-involved FSI crashes, both are significant at the 95% level. Overall, the results suggest that platform stops have considerable safety benefits for pedestrians. Implications for policy and areas for future research are explored.     

Influence of pavement condition on horizontal curve safety

Crash statistics suggest that horizontal curves are the most vulnerable sites for crash occurrence. These crashes are often severe and many involve at least some level of injury due to the nature of the collisions. Ensuring the desired pavement surface condition is one potentially effective strategy to reduce the occurrence of severe accidents on horizontal curves. This study sought to develop crash injury severity models by integrating crash and pavement surface condition databases. It focuses on developing a causal relationship between pavement condition indices and severity level of crashes occurring on two-lane horizontal curves in Texas. In addition, it examines the suitability of the existing Skid Index for safety maintenance of two-lane curves. Significant correlation is evident between pavement condition and crash injury severity on two-lane undivided horizontal curves in Texas. Probability of a crash becoming fatal is appreciably sensitive to certain pavement indices. Data suggested that road facilities providing a smoother and more comfortable ride are vulnerable to severe crashes on horizontal curves. In addition, the study found that longitudinal skid measurement barely correlates with injury severity of crashes occurring on curved portions. The study recommends exploring the option of incorporating lateral friction measurement into Pavement Management System (PMS) databases specifically at curved road segments.     

The relative contribution of system failures and extreme behaviour in South Australian crashes

Within the road system, there are compliant road users who may make an error that leads to a crash, resulting in a ‘system failure’, and there are also road users who deliberately take risks and display dangerous or ‘extreme’ behaviours that lead to a crash. Crashes resulting from system failures can be addressed through improvements to road system design more readily than crashes resulting from extreme behaviours. The classification of crash causation in terms of system failures or extreme behaviour is important for determining the extent to which a Safe System approach (i.e. improvements to road system design to serve compliant road users) is capable of reducing the number of crashes. This study examined the relative contribution of system failures and extreme behaviour in South Australian crashes as identified from information in Coroner’s investigation files and in-depth crash investigations conducted by the Centre for Automotive Safety Research (CASR). The analysis of 189 fatal crashes, 272 non-fatal metropolitan injury crashes and 181 non-fatal rural crashes indicated that very few non-fatal crashes (3% metropolitan, 9% rural) involved extreme behaviour by road users and, even in fatal crashes, the majority (54%) were the result of system failures. Fatal crashes resulting from system failures were more likely than those resulting from extreme behaviour to occur during the day, on weekdays, in rural areas and on roads with high speed limits. Findings from the current study suggest that improvements to the road transport system (i.e. forgiving road infrastructure, appropriate speed limits, and safe vehicle design) can be expected to be much more effective in reducing crashes than concentrating on preventing extreme behaviours. Such a strategy could reduce the incidence and severity of a large proportion of crashes in South Australia.     

Nilsson's Power Model connecting speed and road trauma: Applicability by road type and alternative models for urban roads

Nilsson (1981) proposed power relationships connecting changes in traffic speeds with changes in road crashes at various levels of injury severity. Increases in fatal crashes are related to the 4^th power of the increase in mean speed, increases in serious casualty crashes (those involving death or serious injury) according to the 3^rd power, and increases in casualty crashes (those involving death or any injury) according to the 2^nd power. Increases in numbers of crash victims at cumulative levels of injury severity are related to the crash increases plus higher powers predicting the number of victims per crash. These relationships are frequently applied in OECD countries to estimate road trauma reductions resulting from expected speed reductions. The relationships were empirically derived based on speed changes resulting from a large number of rural speed limit changes in Sweden during 1967-1972. Nilsson (2004) noted that there had been very few urban speed limit changes studied to test his power model. This paper aims to test the assumption that the model is equally applicable in all road environments. It was found that the road environment is an important moderator of Nilsson's power model. While Nilsson's model appears satisfactory for rural highways and freeways, the model does not appear to be directly applicable to traffic speed changes on urban arterial roads. The evidence of monotonically increasing powers applicable to changes in road trauma at increasing injury severity levels with changes in mean speed is weak. The estimated power applicable to serious casualties on urban arterial roads was significantly less than that on rural highways, which was also significantly less than that on freeways. Alternative models linking the parameters of speed distributions with road trauma are reviewed and some conclusions reached for their use on urban roads instead of Nilsson's model. Further research is needed on the relationships between serious road trauma and urban speeds.     

Road safety engineering: an effective tool in the fight against whiplash injuries

Road safety engineering can play an integral part in the prevention of whiplash injuries. While improvements to vehicle design can reduce the severity of whiplash injuries when a crash occurs, improvements to road safety can prevent whiplash-inducing crashes from occurring in the first place. Whiplash injuries are most commonly associated with rear end crashes. Unfortunately, rear end crashes are also the most common type of crash at urban signalized intersections, where the majority of crashes occur in British Columbia, Canada. The Insurance Corporation of British Columbia (ICBC), through the road improvement program, has been funding road improvements in order to reduce the frequency of collisions at high crash locations in British Columbia. Several road safety engineering countermeasures specifically targeted at rear end collisions have been researched and deployed. These countermeasures include simple and affordable solutions such as signal visibility enhancements, as well as complex and expensive solutions such as intersection geometric upgrades. When appropriately used, these countermeasures have proven to be extremely cost-effective in reducing the frequency of rear end collisions. Widespread application of signal visibility enhancements is now being pursued to further decrease the risk of rear end collisions and whiplash injuries. Costs are the direct cost of the ICBC portion of the investment and benefits are only those associated with reduced insurance claims over a 2-year period.     

The burden of road trauma due to other people's drinking

The purpose of this study was to estimate the burden of road traffic injury due to alcohol consumption by someone other than the injured party. We estimated the number and proportion of these traffic deaths and non-fatal traffic injuries, and the associated social costs, for a five-year period (2003–2007) in New Zealand. We found that more than 40% of alcohol-related crash injuries in New Zealand are suffered by people who have not themselves been drinking. While the rate of road traffic injuries and the involvement of alcohol peak amongst young adults, so too does the proportion of all road traffic crash injuries that are due to other people's drinking, reaching one in five in the 15–19-year age group. Most innocent victims are car passengers, and this includes almost all children who are injured by drink driving. For a large majority of the children injured, the driver affected by alcohol is the driver of their own car. Using official cost figures, alcohol-related injuries to innocent victims cost the country more than half a billion dollars per year.     

Applying quantile regression for modeling equivalent property damage only crashes to identify accident blackspots

Hot spot identification (HSID) aims to identify potential sites—roadway segments, intersections, crosswalks, interchanges, ramps, etc.—with disproportionately high crash risk relative to similar sites. An inefficient HSID methodology might result in either identifying a safe site as high risk (false positive) or a high risk site as safe (false negative), and consequently lead to the misuse the available public funds, to poor investment decisions, and to inefficient risk management practice. Current HSID methods suffer from issues like underreporting of minor injury and property damage only (PDO) crashes, challenges of accounting for crash severity into the methodology, and selection of a proper safety performance function to model crash data that is often heavily skewed by a preponderance of zeros. Addressing these challenges, this paper proposes a combination of a PDO equivalency calculation and quantile regression technique to identify hot spots in a transportation network. In particular, issues related to underreporting and crash severity are tackled by incorporating equivalent PDO crashes, whilst the concerns related to the non-count nature of equivalent PDO crashes and the skewness of crash data are addressed by the non-parametric quantile regression technique. The proposed method identifies covariate effects on various quantiles of a population, rather than the population mean like most methods in practice, which more closely corresponds with how black spots are identified in practice. The proposed methodology is illustrated using rural road segment data from Korea and compared against the traditional EB method with negative binomial regression. Application of a quantile regression model on equivalent PDO crashes enables identification of a set of high-risk sites that reflect the true safety costs to the society, simultaneously reduces the influence of under-reported PDO and minor injury crashes, and overcomes the limitation of traditional NB model in dealing with preponderance of zeros problem or right skewed dataset.