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Apeldoorn, Netherlands

Stipdonk H.,SWOV | Wesemann P.,SWOV | Ale B.,Technical University of Delft
Safety Science

Road safety policy plans often require robust calculation of the expected number of road casualties in a certain target year. The relevance of such estimations should be measured by their power to influence and support safety policy makers. Thus, techniques to evaluate the safety developments and the estimating methods must be sound, robust, and preferably accepted by both policy makers and the scientific community. In this paper, we concentrate on choosing an appropriate model used for the calculation, rather than on statistical techniques. We calculate a casualty rate from casualty data and mobility (distance travelled) data, which is extrapolated and subsequently multiplied by an expected future distance travelled. After correction for separately assessed effects of additional safety measures, the number of casualties is estimated. We investigate a method where this is done after both mobility data and casualty data are stratified into properly chosen subsets. Projecting these different trends generally leads to a result that differs from the projection of the aggregated data. Also, stratification enables incorporation in the estimation of explaining factors or additional measures related to a specific subset of the casualties. The principles of stratified projections are illustrated by three Dutch projections which were carried out between 2006 and 2008. Also, some preliminary results of further research on stratification are given. The results imply that the rates of change in casualty rate for different traffic modes or driver age, are not necessarily equal. We propose that these specific decreasing trends are a consequence of external influencing factors. © 2010 Elsevier Ltd. Source

Stipdonk H.,SWOV | Reurings M.,SWOV
Traffic Injury Prevention

Objective: To describe and apply a method to assess the effect on road safety of a modal shift from cars to bicycles.Method: Ten percent of all car trips shorter than 7.5 km were assumed to be replaced by bicycle trips. Single-vehicle and multivehicle crashes involving cars and/or bicycles were considered. The safety of car occupants and cyclists was taken into account as well as the safety of other road users involved in such crashes. The computations were carried out by age and gender. Assuming constant risk (casualties per distance traveled), the expected number of accidents is proportional to the mobility shift. Several types of risk were considered: the risk of being injured as a car driver or cyclist and the risk of being involved as a car driver or cyclist in a crash in which another road user is injured.Results: The results indicated that the total gain of the modal shift was negative for fatalities, which means that there was a net increase in the number of fatalities. The modal shift was advantageous for young drivers and disadvantageous for elderly drivers. In addition, it was more positive for males than for females. The turning point was around the age of 35. For hospitalized casualties, due to the strong influence of the many hospitalized cyclists in nonmotorized vehicle crashes, there was a strong negative overall effect, and the modal shift resulted in a positive effect for 18- and 19-year-old males only.Overall, a small increase (up to 1%) in the number of cyclist fatalities and a greater increase of 3.5 percent in the number of inpatients was expected. The increase in casualties was mainly due to the proportion of single-vehicle bicycle crashes with serious injuries in relation to the total number of injured cyclists. The effect of the modal shift was shown to depend on age and gender, resulting in fewer casualties for younger drivers and for women.Conclusions: It is possible to provide a first approximation of the effect on road safety of a mobility shift from cars to bicycles. This approximation indicates that, in general, road safety does not benefit from this modal shift. The effect differs for gender and age groups. Elderly drivers are safer inside a car than on a bicycle. For the number of hospitalized casualties, the modal shift increases the number of casualties for practically all ages and both genders. © 2012 Copyright Taylor and Francis Group, LLC. Source

Goldenbeld C.,SWOV | Houtenbos M.,SWOV | Ehlers E.,University of California at Berkeley | De Waard D.,University of Groningen
Journal of Safety Research

Introduction: In the Netherlands, a survey was set up to monitor the extent of the use of portable, electronic devices while cycling amongst different age groups of cyclists and to estimate the possible consequences for safety. Method: The main research questions concerned age differences in the self-reported use of electronic devices while cycling, self-reported crash involvement and risk, and self-reported compensatory behaviour. Teen cyclists (12-17 years) and young adult cyclists (18-34 years) were more frequent users, and also more indiscriminate users of portable devices while cycling than middle-aged and older adult cyclists (35-49 years; 50 + years). Results: After statistical correction for influences on crash risk of urbanization level, weekly time spent cycling, and cycling in more demanding traffic situations, the odds of being involved in a bicycle crash were estimated to be higher for teen cyclists and young adult cyclists who used electronic devices on every trip compared to same age groups cyclists who never used these devices. For middle-aged and older adult cyclists, the use of portable electronic devices was not a significant predictor of bicycle crashes, but frequency of cycling in demanding traffic situations was. Possible implications for education or legal measures are discussed. Impact on Industry: Results may inform researchers, policy makers, and cyclists themselves. Educational campaigns may use risk information to warn young cyclists about risk of device use while cycling. © 2012 National Safety Council and Elsevier Ltd. All rights reserved. Source

De Waard D.,University of Groningen | Houwing S.,SWOV | Lewis-Evans B.,University of Groningen | Twisk D.,SWOV | Brookhuis K.,University of Groningen
Transportation Research Part F: Traffic Psychology and Behaviour

Objective: According to international data estimates the proportion bicyclists with a positive Blood Alcohol Concentration (BAC) who are involved in accidents ranges from 15% to 57%. This large variance, and the fact that the reliance on accident statistics means that only the BAC of injured bicyclists is being collected, shows that we do not really know what the average and variation in BAC of bicyclists is, particularly on nights out. Method: On a total of four nights between 5. PM and 8. AM BAC levels of bicyclists were collected with a Breathalyser (N = 687). Samples were collected in two Dutch cities, one with a high (Groningen), and one with a modest, student population (The Hague). Results: The results showed that the percentage of bicyclists who had alcohol in their blood rose over the night from 7.7% at 6. PM to over 89% after 1. AM. Furthermore, the percentage of bicyclists with an illegal BAC above 0.5. g/l rose from zero percent at 6. PM to 68% at 1. AM. The average BAC of bicyclists with a BAC above zero was 0.79. g/l. Differences between the two cities were limited. Conclusion: Cycling with illegal levels of blood alcohol turns out to be very common on nights out in the Netherlands. © 2015 Elsevier Ltd. Source

Weijermars W.,SWOV | Wesemann P.,SWOV
Transportation Research Part A: Policy and Practice

Road safety forecasting and ex-ante evaluation of road safety policy are useful tools in policy making. This paper illustrates the use of these instruments in policy making in the Netherlands. As part of an interim evaluation of achieving Dutch road safety targets, the numbers of fatalities and serious road injuries were estimated for 2020. From these forecasts, it was concluded that the target for serious road injuries most probably would not be met without additional policy measures. Therefore, the Minister of Infrastructure and the Environment in the Netherlands decided to take additional measures. From an ex-ante evaluation of these measures, it was concluded that also with these additional measures the target for the number of serious road injuries in 2020 will most probably not be met. © 2013 Elsevier Ltd. Source

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