The lack of good road crash data is a serious obstacle to analysing road safety problems in Low-and Middle-Income countries (LMICs) and this complicates, for example, the sound assessment of road safety interventions. Police crash reports are the main source of crash data, but often have significant limitations. This paper describes a complementary new methodology for road crash data collection called the Local Record Keeper (LRK) methodology. This methodology deploys trained people from the local community and a new supervisory and quality control process to record road crashes. A comprehensive description of the LRK methodology is provided. The LRKs were able to collect most of the data in the crash forms without difficulty. The LRK methodology recorded significantly more crash data than the Police and provided details on crash location and road user involvement that were important input for the design of a speed management programme on a rural highway that traverses three villages in Bangladesh. A 19.7% reduction of the mean speed caused by the speed management programme was accompanied by a recorded reduction in the LRK data of 66.7% in the number of fatalities, and 59.4% in the number of serious injuries. These recorded reductions as a result of measured speed reductions were consistent with what has been reported in the literature. It is recommended to consider the LRK methodology as a complementary source of crash data in LMICs.

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More than one third of all road deaths in the Netherlands and more than two thirds of seriously injured casualties are cyclists. In recent years these shares have increased, despite the fact that the implementation of Safe System principles has been leading in road safety policy and has been successful in reducing the total number of road deaths. However, the annual number of fatalities among cyclists failed to decline and the number of injuries among cyclists has been increasing, especially in single-bicycle crashes. This raises the question why until now Safe System implementation has failed to contribute to the reduction of the number of casualties among cyclists. This question is urgent because of the goal to reduce the number of road deaths and serious traffic injuries in the Netherlands to (virtually) ZERO by 2050. This ambition is in line with the objectives of the European Union. The causes of the unfavourable developments in road safety for cyclists in the Netherlands and which problems require a solution are examined. This raises two questions: can improved implementation of Safe System measures reverse the negative trend, and can this result in ZERO cycling casualties in the future. The discussion involves investigating three dimensions: exposure, crash risk, and injury risk. The opportunities that technological developments may offer in future decades are also considered. It is concluded that Safe System implementation will include opportunities to make cycling considerably safer in the Netherlands. However, we face too many uncertainties to allow for developing scenarios that show how close the Netherlands will be to ZERO cyclists casualties.

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The year 2020 was an extraordinary year due to the COVID-19 pandemic. This pandemic resulted in lockdowns and confinements globally and emptier streets and roads. Traffic patterns and traffic composition (modal split) changed considerably during the pandemic and as a consequence the number of people killed and injured in road crashes. The aim of this research is to present the number of road fatalities and the fatality rates (fatalities per kilometer driven) in 2020 and to compare these numbers and rates with the previous period (2017–2019), a baseline. An online questionnaire was distributed among the forty countries that are members of the International Safety Data and Analysis Group (IRTAD) in the International Transport Forum and 24 were in a position to submit the requested information before the 1st of June 2021. The questionnaire requested information on the monthly number of fatalities on a national level for four years, (2017–2020) and on kilometres driven. The number of fatalities in 2020 was 17.3% lower in the 24 participating countries compared with the baseline period and the reduction is almost seven times higher than annually in these countries in the period 2010–2019. The reduction took place in spring 2020 and not so much in the remainder of the year. The highest reduction were measured among young (0–17) and elderly people (75 and older), with public transport and on motorways. With the exception of one country, reductions in fatalities have been measured in all countries, however we observe major differences between countries. Regarding fatality rates (fatalities per vehicle kilometer travelled), we also observe major differences between countries and not a stable pattern over 2020 and a remarkable increase in April 2020, the month with the largest fatality reduction. Countries with severe COVID-19 restrictions do not necessarily demonstrate the greatest reductions in road fatalities. It is recommended to carry our further analysis to find explanations for the results and for the differences between the countries.

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In current motorway design practice, microscopic simulation is used to assess the traffic safety and capacity implications of design variants. Many different simulation packages are available, and many researchers have invested effort in improving and calibrating models that describe driving behavior. This paper examines traffic simulation models for merging situations in high traffic volume. Based on a multicriteria analysis, two simulation software packages (VISSIM version 10 and MOTUS) were selected and calibrated using a recently collected set of rich empirical trajectory data from an on-ramp, an off-ramp, and two weaving segments in the Netherlands. The results show that both packages are as yet unable to simulate turbulent traffic around motorway ramps realistically, in terms of lane change locations and headway distribution. This is a drawback when assessing traffic operations for specific designs. The simulated gap acceptance distributions were found to have comparable shapes as they were derived from empirical data. This is an advantage when assessing the traffic safety of a specific design.

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Over the years the characteristics of traffic on Dutch motorways has changed, but its design guidelines did not develop as rapidly and large parts remain unchanged since the first guidelines from the 1970s. During the latest revision of the Dutch motorway design guidelines it became clear that a solid and comprehensive theoretical, or evidence based, background was lacking for the validity of the prescribed ramp spacing and required length for weaving segments. This article presents the underpinning of revising the Dutch design manual for motorways for turbulence in traffic. For this study loop detector data at eight on-ramps and five off-ramps were collected as well as empirical trajectory data at fourteen different on-ramps (three), off-ramps (three) and weaving segments (eight) in The Netherlands. The results show that the areas around ramps that are influenced by turbulence are smaller than described in the design manuals and that, in their present form, the microscopic simulation software packages VISSIM and MOTUS fail to simulate the number and location of lane-changes around ramps realistically.

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Statistical methods such as Poisson distribution, negative binomial regression (NB), and zero inflated negative binomial regression (ZINB) have generally been used in road safety studies to establish the complex relationships between variables. Over the last few years, the artificial neural networks (ANN) model has also been used. The ANN model does not have any prior limitations such as the equality condition of mean and variance observed in Poisson regression. However, though the ANN model has been used in the analysis of different accident types, to the best of our knowledge, no study has used the ANN model for establishing this relationship with truck accident data on divided multilane interurban roads. In this study, the road sections D750/07–D750/15 in Ankara–Aksaray–Eregli, Turkey, were considered and truck accident data from 2008 to 2011 were analyzed using NB and ANN. The analysis show that the ANN model has lower errors and higher R² values than NB and performs slightly better than NB for predicting the number of trucks involved in accidents. Based on a comparison of performances the study concludes, that ANN could be used as an alternative model for analyzing truck accident data on divided multilane interurban roads in Turkey.

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In the vicinity of ramps, drivers make route choices, change lanes and in most cases also adjust their speeds. This can trigger anticipatory behaviour by the surrounding vehicles, which are also reflected in lane changes and/or changes in speed. This phenomenon is called turbulence and is widely recognised by the scientific literature and various design guidelines. However the knowledge about the characteristics of turbulence is limited. This study investigates the microscopic characteristics of driving behaviour around 14 different on-ramps (3), off-ramps (3) and weaving segments (8) in The Netherlands, based on unique empirical trajectory data collected from a video camera mounted underneath a hovering helicopter. The data analysis reveals that lane changes caused by merging and diverging vehicles create most turbulence, that an increase in the amount of traffic results in a higher level of turbulence and that an increase in the available length for merging and diverging results in a lower level of turbulence. The results of this study are useful for improving the road design guidelines and for modelling driving behaviour more realistically.

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This paper presents analyses of how the economic recession that started in 2008 has influenced the number of traffic fatalities in OECD countries. Previous studies of the relationship between economic recessions and changes in the number of traffic fatalities are reviewed. Based on these studies, a causal diagram of the relationship between changes of the business cycle and changes in the number of traffic fatalities is proposed. This causal model is tested empirically by means of multivariate analyses and analyses of accident statistics for Great Britain and Sweden. Economic recession, as indicated both by slower growth of, or decline of gross national product, and by increased unemployment is associated with an accelerated decline in the number of traffic fatalities, i.e. a larger decline than the long-term trend that is normal in OECD countries. The principal mechanisms bringing this about are a disproportionate reduction of driving among high-risk drivers, in particular young drivers and a reduction of fatality rate per kilometre of travel, probably attributable to changes in road user behaviour that are only partly observable. The total number of vehicle kilometres of travel did not change very much as a result of the recession. The paper is based on an ITF-report that presents the analyses in greater detail.

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Estimates by the World Health Organization suggest that, on a yearly basis, road crashes kill 1.25 million people—nearly 3400 road fatalities per day—and injure up to 50 million. Traffic injuries are not equally spread over the world, however; some countries are hit harder than others, and the chance of being killed in a road crash depends on where one lives. Almost 90% of all traffic casualties occur in low- and middle-income countries (LMIC). Globally, the number of fatalities per 100,000 population (mortality rate) ranges from less than 3 to almost 40. The rate is less than 9 in high-income countries (HIC) but averages around 20 in LMIC, with the African region demonstrating the highest rate (26.6). While road safety trends have been positive in HIC over the last few decades, trends in LMIC are not telling a positive story: road fatalities are expected to increase to almost 2 million road fatalities per year by 2020. The United Nations has adopted several resolutions on road safety and proposes actions to tackle the global road safety crisis. Considering the current level of road safety to be unacceptable, the UN has taken several initiatives. One effort, the Decade of Action for Road Safety 2011–2020, has generated substantial activity around the world over the last couple of years. Furthermore, it is very encouraging that the UN included road safety in the Sustainable Development Goals that it laid out in September 2015. Road safety is part of the public health agenda and the urban development agenda. Measured in “real actions,” however, the responses so far from the overall global community and individual countries do not suggest that we are already on the right track to bringing down the death toll on roads. The future of road safety is uncertain and definitely not the same for all regions of the world. Countries with a mature road safety approach and an ambition to make further progress are expected to move in the direction of a pro-active approach: a Safe System approach. It is reported that many LMIC, meanwhile, are on the brink of designing road safety strategies and implementing action plans. The international community is willing to support LMIC, but LMIC cannot simply copy successful HIC strategies because local circumstances differ. The principles of successful HIC strategies are applicable, but the priorities and action plans should take root in and align with local conditions.

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Traffic is more turbulent around motorway ramps due to route choice-related lane changes and anticipatory or cooperative manoeuvres. These manoeuvres result in changes in speed and headways and have a negative influence on traffic safety and capacity. However, the distance upstream where turbulence starts and the distance downstream where it dissolves are yet unknown. In this paper, we propose a new method for detecting the start and end distances of turbulence. This method relies on the analysis of large quantities of empirical loop detector data from multiple on-ramps and off-ramps at different sites. By comparing the traffic operations near ramps to those on a regular motorway section, the length of the turbulence influence area can be estimated. The scope of the research is limited to three-lane motorways in the Netherlands, and shows that the distribution of traffic over the motorway lanes is a useful indicator for turbulence.

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Turbulence in traffic is a commonly known phenomenon, but the exact characteristics of this phenomenon are not yet clear. Turbulence reflects individual changes in speed, headways, and lanes in the traffic stream. The current freeway design guidelines prescribe measures for handling turbulence, such as sufficient ramp spacing and spacing between road discontinuities. In situations where there is little available space between discontinuities, it might be necessary to make a trade-off between costs and safety and operations. For a valid trade-off, more insight is needed on the safety and operations effects of deviations from the guidelines. Much research has been done on the causes of turbulence and their effects on safety and operations. This paper proposes a theoretical framework for the turbulence phenomenon that facilitates the comparison of the available methodologies that can be used to evaluate a freeway design on the matter of turbulence and its impact on traffic operations and safety. The main finding of this review is that the currently available methodologies lack the ability to evaluate the impact of freeway turbulence on operations and safety simultaneously. The paper makes recommendations to overcome the limitations of current methodologies and for further research possibilities to improve these methodologies.

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Bone morphogenetic protein-2 (BMP-2) gene delivery has shown to induce bone formation in vivo in cell-based tissue engineering. In addition, the chemoattractant stromal cell-derived factor-1α (SDF-1α, also known as CXCL12) is known to recruit multipotent stromal cells towards its release site where it enhances vascularisation and possibly contributes to osteogenic differentiation. To investigate potential cooperative behaviour for bone formation, we investigated combined release of BMP-2 and SDF-1α on ectopic bone formation in mice. Multipotent stromal cellseeded and cell-free constructs with BMP-2 plasmid DNA and /or SDF-1α loaded onto gelatin microparticles, were implanted subcutaneously in mice for a period of 6 weeks. Histological analysis and histomorphometry revealed that the onset of bone formation and the formed bone volume were both enhanced by the combination of BMP-2 and SDF-1α compared to controls in cell-seeded constructs. Samples without seeded multipotent stromal cells failed to induce any bone formation. We conclude that the addition of stromal cellderived factor-1α to a cell-seeded alginate based bone morphogenetic protein-2 plasmid DNA construct has an additive effect on bone formation and can be considered a promising combination for bone regeneration.@en

Over the past decades, road safety in highly-motorised countries has made significant progress. Although we have a fair understanding of the reasons for this progress, we don't have conclusive evidence for this. A new generation of road safety management approaches has entered road safety, starting when countries decided to guide themselves by setting quantitative targets (e.g. 50% less casualties in ten years' time). Setting realistic targets, designing strategies and action plans to achieve these targets and monitoring progress have resulted in more scientific research to support decision-making on these topics. Three subjects are key in this new approach of evidence-based and data-driven road safety management: ex-post and ex-ante evaluation of both individual interventions and intervention packages in road safety strategies, and transferability (external validity) of the research results. In this article, we explore these subjects based on recent experiences in four jurisdictions (Western Australia, the Netherlands, Sweden and Switzerland). All four apply similar approaches and tools; differences are considered marginal. It is concluded that policy-making and political decisions were influenced to a great extent by the results of analysis and research. Nevertheless, to compensate for a relatively weak theoretical basis and to improve the power of this new approach, a number of issues will need further research. This includes ex-post and ex-ante evaluation, a better understanding of extrapolation of historical trends and the transferability of research results. This new approach cannot be realized without high-quality road safety data. Good data and knowledge are indispensable for this new and very promising approach.

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The International Road Traffic and Accident Database (IRTAD)@en