Fred Wegman

Ten years of sustainable safety in the netherlands: an assessment

In the 1990s, the Institute for Road Safety Research (SWOV) in the Netherlands introduced the vision of sustainable safety. In a sustainably safe traffic system, crashes are prevented as much as possible, and when prevention is not possible, the probability of severe injury is reduced to almost zero. In 1998, implementation of the vision commenced with the start-up program. Ten years after the start-up program, there was an investigation of how implementation of the measures that emanated from or were in line with the vision of sustainable safety had progressed and what effects these measures have had on safety. The assessment indicated that a substantial number of traffic safety measures were implemented from 1998 through 2007. Many actions taken within the framework of the start-up program were aimed at improving infrastructure safety; the most important actions were categorization of the road network and traffic calming measures such as the construction of 30- and 60-km/h zones. In addition, traffic enforcement increased as a result of the establishment of dedicated regional traffic enforcement teams. The crashworthiness of vehicles also improved. These measures had a positive effect on traffic safety. Each individual measure prevented casualties. Moreover, the fatality rate decreased from 7.3 fatalities per billion kilometers traveled in 1998 to 4.7 per billion in 2007. It is estimated that together the measures prevented 300 to 400 fatalities in 2007 (32% to 34% fewer than expected) and 1,600 to 1,700 fatalities from 1998 through 2007. Finally, a benefit-cost analysis indicates that the measures were also cost beneficial (benefit-cost ratio 3.6:1).

Analyzing road design risk factors for run-off-road crashes in The Netherlands with crash prediction models.

PROBLEM About 50% of all road traffic fatalities and 30% of all traffic injuries in the Netherlands take place on rural roads with a speed limit of 80 km/h. About 50% of these crashes are run-off-road (ROR) crashes. To reduce the number of crashes on this road type, attention should be put on improving the safety of the infrastructure of this road type. With the development of a crash prediction model for ROR crashes on rural roads with a speed limit of 80 km/h, this study aims at making a start in providing the necessary new tools for a proactive road safety policy to road administrators in the Netherlands. METHOD The paper presents a basic framework of the model development, comprising a problem description, the data used, and the method for developing the model. The model is developed with the utilization of generalized linear modeling in SAS, using the Negative Binomial probability distribution. A stepwise approach is used by adding one variable at a time, which forms the basis for striving for a parsimonious model and the evaluation of the model. The likelihood ratio test and the Akaike information criterion are used to assess the model fit, and parameter estimations are compared with literature findings to check for consistency. RESULTS The results comprise two important outcomes. One is a crash prediction model (CPM) to estimate the relative safety of rural roads with a speed limit of 80 km/h in a network. The other is a small set of estimated effects of traffic volume and road characteristics on ROR crash frequencies. PRACTICAL APPLICATIONS The results may lead to adjustments of the road design guidelines in the Netherlands and to further research on the quantification of risk factors with crash prediction models.

Reducing Drink Driving in Low- and Middle-Income Countries: Challenges and Opportunities

A great deal of progress has been made in reducing alcohol-impaired driving crashes and the related injuries and deaths in countries around the world. Unfortunately, this progress has not been shared by many low- and middle-income countries. In response to this disparity, a variety of international efforts have been undertaken, including the Drink Driving Initiative of Global Actions on Harmful Drinking, being carried out with a focus on 6 low- and middle-income countries where drink driving is a significant issue. These countries are China, Colombia, Mexico, Nigeria, Russia, and Vietnam. This article provides an overview of situational assessments that describe the current drink driving problems in these countries and the laws, policies, enforcement efforts, and public attitudes related to drink driving. These descriptions show clearly that there are particular challenges faced by the countries discussed here. Some, such as a lack of reliable traffic safety data, are common to most of the countries. This lack of data may be interrelated with the lack of well-developed drink driving policies. Other challenges vary depending on the particular geographic, economic, cultural, and social situations in each country. The assessments indicate the need for a focus on capacity building at the organizational and individual level in the target countries. The assessments also indicate that a long-term commitment to strengthening policies, implementation, and evaluation will be needed. This deeper understanding of the situations in each of these countries is already being put to use in what we hope is the beginning of an important and lifesaving process.

Development of Footprint Methodology for Road Safety

Progress in traffic safety is the result of many developments, including political decisions, the development of safety plans and actions, and the implementation of these plans and actions. This paper explores ways of presenting road safety information to help decision makers understand how the interaction between many factors leads to improvements in the safety quality components of the traffic system and finally to reductions in road casualties. Simple one-factor bar charts cannot be used to this effect. In the SUNflower+6 project, a methodology has been developed that results in a “road safety footprint” for a country or jurisdiction. This footprint helps to identify strong and weak points in the traffic system, to direct to further and more detailed analyses, and to assist in finding ways to further road safety improvements. The development of this method was one of the goals of the SUNflower+6 project, which aimed to assess the state of the art in road safety of nine European countries and presented recommendations for the improvement of road safety in these countries and the European Commission. A footprint provides a representation of the road safety status and development over time in a country and can be used for benchmarking purposes. At this stage, the proposed methodology is considered to be a first step that may eventually grow into a widespread tool for benchmarking road safety. In the near future, further research will be conducted to learn from practical application of the developed methodology in more countries and jurisdictions in the world.

How did the economic recession (2008–2010) influence traffic fatalities in OECD-countries?

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.

The Effects of Cyclists Present at Rural Intersections on Speed Behavior and Workload of Car Drivers: A Driving Simulator Study

Objective: The objective was to gain insight into how the number of cyclists, the cyclists approach direction, and the cyclists action affect the speed and mental workload of drivers approaching rural intersections. In addition, the effects of a speed-reducing measure on the interaction between cyclists and motorized traffic were examined. Methods: An experiment was conducted in a moving-base driving simulator. Thirty participants completed 3 runs each in 3 conditions: a baseline, a plateau, and a chicane condition. Participants drove an 80 km/h rural distributor road with 8 intersections. Eight cyclist scenarios were developed varying in the number of cyclists and the direction from which they approached the participants’ lane. The Peripheral Detection Task was used to measure workload objectively and continuously. Results: A plateau ahead of the intersection resulted in drivers entering the bicycle crossing with lower driving speeds but did not result in less serious potential conflicts compared to intersections without the speed-reducing measure. With respect to the presence of cyclists, drivers approaching the intersection without cyclists reached a minimum speed at a greater distance from the bicycle crossing compared to approaching the intersection with multiple cyclists in the baseline condition. At intersections with plateaus, drivers drove slower when encountering multiple cyclists compared to no cyclists. At intersections without the speed-reducing measure, drivers drove slower, decelerated stronger, and decelerated at a shorter distance to the bicycle crossing when encountering a suddenly crossing cyclist compared to a yielding cyclist. Conclusions: Although drivers have the right of way at rural intersections, drivers’ speed behavior was affected by the number and action of cyclists. From a road safety point of view, driving speeds at rural intersections need to be further reduced to limit the seriousness of potential conflicts between cyclists and motorized traffic.

Sustainable Safety in the Netherlands: Evaluation of National Road Safety Program

This paper deals with prevention of human errors by proper road planning, road design, and improvement of existing roads within the framework of the Dutch Sustainable Safety vision. This vision focuses on three design principles for road networks and for roads and streets: functionality, homogeneity, and predictability. The ambition is to reduce considerably the number of crashes and casualties and maintain the Netherlands as one of the countries with the best road safety records. This vision was launched at the beginning of the 1990s and accepted as a formal part of Dutch policies in the mid-1990s. It resulted in a so-called Start-Up Program on Sustainable Safety, not only addressing the planning and design of road infrastructure but strongly emphasizing those aspects. Contents of the start-up program are described as the process leading to implementation. An overview presents different (road infrastructure) components of the start-up program and the estimated effects on road crashes. These components ar...

Critical Assessment of Methodologies for Operations and Safety Evaluations of Freeway Turbulence

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.

Macroscopic traffic flow changes around ramps

ABSTRACT 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.

Analyzing truck accident data on the interurban road Ankara–Aksaray–Eregli in Turkey: Comparing the performances of negative binomial regression and the artificial neural networks models

ABSTRACT 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.