The properties of Safety Performance Indicators in target setting, projections and safety design of the road transport system

Adjusting vehicle secondary safety ratings to account for crash-avoidance technology fitment using real-world crash and injury data

OBJECTIVES

Publicizing safety ratings of vehicles can motivate manufacturers to prioritize safety and help consumers choose safer vehicles, leading to safer fleets. The benefits of primary safety technologies that prevent crash occurrence are not currently incorporated in current ratings in a way that values their safety benefits consistently. We aimed to propose a method for assigning weights for each safety technology to account for established safety benefits using published effectiveness and prevalence from real-life data.

METHODS

To illustrate this method, we present a worked example calculated using crash and injury data from Australia and New Zealand. The method proposed attenuates the weights for given safety technologies where two or more safety technologies fitted to the same vehicle are effective for the same types of crashes.

RESULTS

In the worked example using Australasian data, large SUVs were estimated to have the largest safety increment from the fitment of all the technologies considered compared to vehicles without these primary safety technologies, with an almost 17% reduction in crash occurrence. Cars with all the technologies fitted had estimated average crash reduction of between 11% and 12%.

CONCLUSIONS

Different market groups have different crash patterns, so the safety attributable to safety technology fitment differs at the market group level. This study presents an approach for providing a summary measure of crash avoidance according to the fitment of safety technologies. If this measure is combined with an estimate of secondary safety (whether derived from existing crash and injury data or from new car crash assessment programs), the combined estimate then represents the important elements of safety provided by the vehicle. The methods presented here form a rational basis for assigning safety ratings to represent the benefits of swiftly developing safety technologies.

Are crash causation studies the best way to understand system failures - Who can we blame?

The search for common and serious single causes of road crashes naturally leads to a concentration on the road user. This is supported by a legal framework in the search for the main cause and the suspect for this cause. In prevention, we havefor decades been more inclined to look for systematic improvements of all elements of the road transport system, and we direct the recommendations for actions towards system designers, organizations, products and services. In this paper the discussion about causation and prevention is broadened in the light of Vision Zero and its approach to prevention of serious and fatal injuries. We also discuss the Swedish judicial system and why the prevention approach has not been legislated or even generally accepted. Occupational health and safety legislation and road rules are compared, as well as how sustainability practices and reporting are tools to apply prevention where organizations have a natural sphere of influence that could mitigate deaths and serious injuries within value chains. It is recommended that we stop using the term causation as it is only directing actions in one direction. There is a risk that the focus on causation, in particular single causes, will deviate actions away from robust prevention countermeasures such as increased seat belt use, relevant speed limits, and well functioning roundabouts and median barriers. Furthermore, there is also a risk that important preventative actions from organizations are overlooked.

Impact of quantitative safety targets on road fatality reduction: an empirical support toward governance plan

Introduction

The role of quantitative target setting has become an important topic in debates on the improvement of road safety performance. Specifically, there are questions regarding the relationship between quantitative safety targets and their actual effects. Although previous studies have provided important insights into this subject, their empirical findings have largely been equivocal, and research on this topic remains inadequate.

Methods

Based on panel data representing 20 years of observations from 34 OECD member states, we employed nonlinear and linear panel models to investigate whether and how the attributes of quantitative road safety targets (i.e., target ambition and duration) influence their success (i.e., target completion status and rate).

Results

The results indicate that a quantitative target with a higher level of ambition is associated with a lower likelihood and rate of completion, whereas there is no support for a connection between target duration and final completion rate. This suggests that an excessively ambitious target does not necessarily result in better road safety performance and is detrimental to achieving expected fatality reductions.

Conclusion

From an empirical perspective, this study revealed a potential interaction effect between quantitative road safety targets and practical fatality reduction performance, providing government officials and policymakers with essential references for future practices on target setting and governance planning in regard to public health.

Profiling fatal and serious injury crashes in South Australia according to the Swedish transport administration model

OBJECTIVES

This article describes a study examining fatal road crashes in South Australia (SA) according to the safety model developed by the Swedish Road Administration (STA). The STA model is based on the biomechanical limits that human beings can tolerate and specifies a number of elements that must be present for "compliance" with the model: driving at or below the speed limit, driver not intoxicated by alcohol or drugs, vehicle occupants wearing a seatbelt, car with a EuroNCAP rating of 5 stars, car equipped with electronic stability control, and a road with an EuroRAP rating of 4 stars.

METHOD

The study used a sample of 105 fatal crashes in SA in 2010 and 2011 and a comparison sample of 136 serious injury crashes from 2014 to 2017.

RESULTS

It was found that there were high levels of noncompliance with all elements of the STA model, with multiple forms of noncompliance in a clear majority of fatal cases.

CONCLUSIONS

Considerable gains in safety could occur with greater penetration into the SA fleet of 5-star cars fitted with ESC and other vehicle safety technology, especially as the majority of both sets of crashes were of a type involving loss of vehicular control. It is also important to note that risky road user behavior was less common in the serious injury crashes and so a road safety strategy focusing on changing road user behavior will be ineffective for addressing the major factors contributing to non-fatal road trauma.

Estimating, and setting targets for, the resilience of transport infrastructure

To ensure that transport infrastructure provides acceptable levels of service with respect to extreme events, the resilience of the infrastructure needs to be estimated and targets for it need to be set. In this paper, the methodology proposed in the Foresee EU research project is presented. The methodology allows managers to measure, and set targets for, the resilience of transport systems in all situations. It requires clear definition of the transport system and how the service provided and the resilience are to be measured. The methodology allows consideration of the fact that transport infrastructure managers need to estimate resilience with various degrees of accuracy depending on the specific problem to be addressed, the time frame at disposition and the expertise available. These various levels of accuracy are covered by proposing the use of (a) simulations, (b) indicators whose values are directly related to increases in expected restoration intervention costs and reductions in service, and (c) the percentage of fulfilment of indicators. Once resilience has been estimated, the methodology provides guidance on how to set resilience targets with or without cost–benefit analysis. For demonstration, the explanation of the steps of the guideline is supported by their use for a simple transport system.

Incidence of seriously injured road users in a Swedish region, 2003-2014, from the perspective of a national road safety policy

Background

Since 1997 Sweden has a policy for road safety called Vision Zero. Given that Vision Zero is mainly used to reduce fatalities among car occupants, the question has been raised by the research community whether a Vision Zero approach promotes health for all road traffic users. The objective is to measure target fulfilment of the national road safety policy for a Swedish region by examining incidence of serious injury during 2003–2014 in rural and urban road spaces with or without implemented measures.

Methods

Data on seriously injured road users, defined as ISS > 8 (Injury Severity Score), were retrieved from STRADA (Swedish Traffic Accident Data Acquisition) together with data from NVDB (National Road Database). These data are used to describe where road users are seriously injured in relation to implemented national policy and using a conceptual model of a road space comprising roads, pavements and tracks for walking and cycling. Seriously injured road users in single and multiple crashes with and without vehicles are included. The development of the incidence is analysed for different road users and places in the road space.

Results

Despite implemented road safety measures in the region, the incidence of seriously injured road users per 100,000 inhabitants in rural areas increased from 7.8 in 2003 to 9.3 in 2014 but doubled in urban areas from 8.0 in to 16.3 respectively. In areas not transformed by Vision Zero, only 36% were injured in rural areas while 64% were injured in urban areas. In contrast, in transformed areas 61% of injuries occurred in rural areas, whereas 39% occurred in urban areas. While the incidence decreased for car occupants on transformed national roads in rural areas, the incidence of serious injuries increased among unprotected road users in urban areas, in particular on pavements and tracks for cycling and walking than on the roads where Vision Zero had been implemented.

Conclusion

The reduction in the incidence for car occupants in the region may not be adequate to contribute to fulfilling the national target. More needs to be done, especially in the urban areas, where more active mobility is desired.

Self-reported and observed seat belt use--A case study: Bosnia and Herzegovina

The issue of seat belt use in middle- and low-income countries is strongly evident and has as a result higher rates of fatalities and seriously injured on the roads. The first systematic field research of the seat belt use while driving was carried out in Bosnia and Herzegovina, in 2011-2012. Research methodology consisted of two mutually conditioned parts (observation and self-reported behavior). Specific features of the methodology used are in the relationship between the observed and interviewed drivers which enabled the analysis of their observed and self-reported behavior while driving. The logistic regression method was used in this work to make the analysis of the influence of personal human characteristics (gender, age, education, exposure) and vehicles' characteristics (age) on the observed and self-reported driving behavior, from the point of view of seat belt use while driving. The influence of the listed factors on driving behavior, depending on road type (urban or rural), was given special attention in the analysis. The paper shows that certain factors do not have the same impact on driving behavior, in various conditions. Based on results from this study, it will be possible to define certain critical groups of road users and the way in which they must be addressed in order to increase the seat belt wearing rate.

Validation of a method to evaluate future impact of road safety interventions, a comparison between fatal passenger car crashes in Sweden 2000 and 2010

When targeting a society free from serious and fatal road-traffic injuries, it has been a common practice in many countries and organizations to set up time-limited and quantified targets for the reduction of fatalities and injuries. In setting these targets EU and other organizations have recognized the importance to monitor and predict the development toward the target as well as the efficiency of road safety policies and interventions. This study aims to validate a method to forecast future road safety challenges by applying it to the fatal crashes in Sweden in 2000 and using the method to explain the change in fatalities based on the road safety interventions made until 2010. The estimation of the method is then compared to the true outcome in 2010. The aim of this study was to investigate if a residual of crashes produced by a partial analysis could constitute a sufficient base to describe the characteristics of future crashes.

RESULT

show that out of the 332 car occupants killed in 2000, 197 were estimated to constitute the residual in 2010. Consequently, 135 fatalities from 2000 were estimated by the model to be prevented by 2010. That is a predicted reduction of 41% compared to the reduction in the real outcome of 53%, from 332 in 2000 to 156 in 2010. The method was found able to generate a residual of crashes in 2010 from the crashes in 2000 that had a very similar nature, with regards to crash type, as the true outcome of 2010. It was also found suitable to handle double counting and system effects. However, future research is needed in order to investigate how external factors as well as random and systematic variation should be taken into account in a reliable manner.

The likelihood of achieving quantified road safety targets: a binary logistic regression model for possible factors

In past several decades, many countries have set quantified road safety targets to motivate transport authorities to develop systematic road safety strategies and measures and facilitate the achievement of continuous road safety improvement. Studies have been conducted to evaluate the association between the setting of quantified road safety targets and road fatality reduction, in both the short and long run, by comparing road fatalities before and after the implementation of a quantified road safety target. However, not much work has been done to evaluate whether the quantified road safety targets are actually achieved. In this study, we used a binary logistic regression model to examine the factors - including vehicle ownership, fatality rate, and national income, in addition to level of ambition and duration of target - that contribute to a target's success. We analyzed 55 quantified road safety targets set by 29 countries from 1981 to 2009, and the results indicate that targets that are in progress and with lower level of ambitions had a higher likelihood of eventually being achieved. Moreover, possible interaction effects on the association between level of ambition and the likelihood of success are also revealed.

Development of road safety performance indicators for trauma management in Europe

Trauma management (TM) covers two types of medical treatment: the initial one provided by Emergency Medical Services (EMS) and a further one provided by permanent medical facilities. There is a consensus in the professional literature that to reduce the severity and the number of road crash victims, the TM system should provide rapid and adequate initial care of injury, combined with sufficient further treatment at a hospital or trauma centre. Recognizing the important role of TM for reducing road crash injury outcome, it was decided, within the EU funded SafetyNet project, to develop road safety performance indicators (SPIs) which would characterize the level of TM systems' performance in European countries and enable country comparisons. The concept of TM SPIs was developed based on a literature study of performance indicators in TM, a survey of available practices in Europe and data availability examinations. A set of TM SPIs was introduced including 14 indicators which characterize five issues such as: availability of EMS stations; availability and composition of EMS medical staff; availability and composition of EMS transportation units; characteristics of the EMS response time, and availability of trauma beds in permanent medical facilities. Basic information on the TM systems was collected in close cooperation with the national expert group. A dataset with TM SPIs for 21 countries was created. It was demonstrated that the countries can be compared using selected TM SPIs. Moreover, a more general comparison of the TM systems' performance in the countries is possible, using multiple ranking and statistical weighting techniques. By both methods, final estimates were received enabling the recognition of groups of countries with similar levels of the TM system's performance. The results of various trials were consistent as to the recognition of countries with high or low level of the TM systems' performance, where in grouping countries with intermediate levels of the TM system's performance some differences were observed. The SafetyNet project's practice demonstrated that data collection for estimating TM SPIs is not an easy task but is realizable for the majority of countries. The TM SPIs' message is currently limited to the availability of trauma care services. Further development of the TM SPIs should focus on characteristics of actual treatment supplied, based on combined police and medical road crash related databases.

Benchmarking road safety of U.S. states: a DEA-based Malmquist productivity index approach

In this study, a DEA based Malmquist index model was developed to assess the relative efficiency and productivity of U.S. states in decreasing the number of road fatalities. Even though the national trend in fatal crashes has reached to the lowest level since 1949 (Traffic Safety Annual Assessment Highlights, 2010), a state-by-state analysis and comparison has not been studied considering other characteristics of the holistic national road safety assessment problem in any work in the literature or organizational reports. In this study, a DEA based Malmquist index model was developed to assess the relative efficiency and productivity of 50 U.S. states in reducing the number of fatal crashes. The single output, fatal crashes, and five inputs were aggregated into single road safety score and utilized in the DEA-based Malmquist index mathematical model. The period of 2002-2008 was considered due to data availability for the inputs and the output considered. According to the results, there is a slight negative productivity (an average of -0.2 percent productivity) observed in the U.S. on minimizing the number of fatal crashes along with an average of 2.1 percent efficiency decline and 1.8 percent technological improvement. The productivity in reducing the fatal crashes can only be attributed to the technological growth since there is a negative efficiency growth is occurred. It can be concluded that even though there is a declining trend observed in the fatality rates, the efficiency of states in utilizing societal and economical resources towards the goal of zero fatality is not still efficient. More effective policy making towards increasing safety belt usage and better utilization of safety expenditures to improve road condition are derived as the key areas to focus on for state highway safety agencies from the scope of current research.

A new method to evaluate future impact of vehicle safety technology in Sweden

In the design of a safe road transport system there is a need to better understand the safety challenges lying ahead. One way of doing that is to evaluate safety technology with retrospective analysis of crashes. However, by using retros- pective data there is the risk of adapting safety innovations to scenarios irrelevant in the future. Also, challenges arise as safety interventions do not act alone but are rather interacting components in a complex road transport system. The objective of this study was therefore to facilitate the prioritizing of road safety measures by developing and applying a new method to consider possible impact of future vehicle safety technology. The key point was to project the chain of events leading to a crash today into the crashes for a given time in the future. Assumptions on implementation on safety technologies were made and these assump- tions were applied on the crashes of today. It was estimated which crashes would be prevented and the residual was analyzed to identify the characteristics of future crashes. The Swedish Transport Administration's in-depth studies of fatal crashes from 2010 involving car passengers (n=156) were used. This study estimated that the number of killed car occupant would be reduced with 53 percent from the year 2010 to 2020. Through this new method, valuable information regarding the characteristic of the future crashes was found. The results of this study showed that it was possible to evaluate future impact of vehicle safety technology if detailed and representative crash data is available.

Road safety risk evaluation and target setting using data envelopment analysis and its extensions

Currently, comparison between countries in terms of their road safety performance is widely conducted in order to better understand one's own safety situation and to learn from those best-performing countries by indicating practical targets and formulating action programmes. In this respect, crash data such as the number of road fatalities and casualties are mostly investigated. However, the absolute numbers are not directly comparable between countries. Therefore, the concept of risk, which is defined as the ratio of road safety outcomes and some measure of exposure (e.g., the population size, the number of registered vehicles, or distance travelled), is often used in the context of benchmarking. Nevertheless, these risk indicators are not consistent in most cases. In other words, countries may have different evaluation results or ranking positions using different exposure information. In this study, data envelopment analysis (DEA) as a performance measurement technique is investigated to provide an overall perspective on a country's road safety situation, and further assess whether the road safety outcomes registered in a country correspond to the numbers that can be expected based on the level of exposure. In doing so, three model extensions are considered, which are the DEA based road safety model (DEA-RS), the cross-efficiency method, and the categorical DEA model. Using the measures of exposure to risk as the model's input and the number of road fatalities as output, an overall road safety efficiency score is computed for the 27 European Union (EU) countries based on the DEA-RS model, and the ranking of countries in accordance with their cross-efficiency scores is evaluated. Furthermore, after applying clustering analysis to group countries with inherent similarity in their practices, the categorical DEA-RS model is adopted to identify best-performing and underperforming countries in each cluster, as well as the reference sets or benchmarks for those underperforming ones. More importantly, the extent to which each reference set could be learned from is specified, and practical yet challenging targets are given for each underperforming country, which enables policymakers to recognize the gap with those best-performing countries and further develop their own road safety policy.

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.