The effect of wind turbines alongside motorways on drivers’ behaviour

This paper presents the results of a first study aimed at investigating whether the presence of wind turbines in close proximity to motorways leads to behavioural adaptations among passing drivers. Empirical data from loop detectors and temporary video cameras were analysed in a study employing a before-and-after design at a site near Rotterdam, The Netherlands. Analyses of driving speed and standard deviation of speed (corrected for trend effects through the use of control sites) were performed as well as analyses of the lateral position and standard deviation of the lateral position and an observation of serious traffic conflicts. The results showed that constructing wind turbines alongside a motorway led to some clearly observable effects on drivers’ behaviour. The analyses of the speed data showed that the mean speed was lowered by 2.24km/h (corrected for trend effects) after the construction of the wind turbines while the standard deviation of the speed significantly increased. After the construction of the wind turbines, drivers took a lateral position somewhat more to the left-hand side in their driving lane. There was an indication close to the 0.05 significance level (p=0.057) that the standard deviation of the lateral position slightly increased when the rotor blades were in transversal position. In the before period as well as in the after period, no serious traffic conflicts were registered. The increase in standard deviation of speed and in lateral position are two factors that intrinsically can have an unfavourable effect on road safety. However, the observed order of magnitude of the change was shown to be quite limited. Earlier research suggests that negative effects on road safety are only expected for changes substantially greater than the ones that were observed in this study. On the other hand, there was a significant reduction in driving speed, which might have a favourable effect on the expected number and severity of crashes, although it could also be a compensatory mechanism that indirectly indicates a reduced driving performance. From these findings, it can be concluded that, based on the observed variables, no substantial negative effects for road safety were found in the present study. The authors recommend continuous monitoring and further research on the topic

Proactive Evaluation of Traffic Signs Using a Traffic Sign Simulator

Traffic signs and pavement markings are a crucial aspect of road design since they are essential sources of information for road users to calibrate their driving behavior, evaluate route possibilities and cope with unexpected events. A proactive evaluation of (the quality of) these road design elements will help to improve the safety performance of the roadway. This paper presents the Traffic Sign Simulator, an innovative research tool to study the influence of these elements on road users’ routing decisions, lane choice and visual behavior, to investigate road users’ comprehension of these signs, and to collect suggestions for improvements. Using a driving simulator mock-up, participants navigate through a full HD video from route(s) in which the planned traffic signs have been digitally implemented using specialized software for camera-tracking and 3D video-integration. Participants’ route and lane choice and their visual behavior (using eye tracking) are monitored while driving through the scenario(s). Laptop preand post-tests are applied to collect additional in-depth information concerning the participants’ processing, comprehension and general evaluation of the traffic signs and suggestions for improvement. The paper illustrates the possibilities of the Traffic Sign Simulator with a case study that examined the effectiveness of temporary work zone signalization (i.e., traffic signs, digital information panels and pavement markings) as it was used during the reconstruction works on the Vilvoorde fly-over near Brussels, one of the busiest interchanges in the Belgian motorway network

Determinants and barriers of walking, cycling and using Personal e-Transporters: a survey in nine European cities

This report describes the results of an extensive online survey that has been conducted to collect empirical data on the psychological determinants and barriers of a travel mode shift in favour of active transport modes. The modes that have been focused on are walking, cycling and the use of Personal e-Transporters (PeTs) (e.g. electric scooter, monowheel, Segway,…). The survey was conducted in nine cities spread over the four countries of the consortium partners involved in the ISAAC-project: Tilburg and Groningen (The Netherlands), Ghent and Liège (Belgium), Trondheim and Bergen (Norway), and Dortmund, Düsseldorf and Berlin (Germany). A representative sample (in terms of age and gender) of 250 respondents per city was interviewed. The aim is to better understand people’s travel mode choices, and to investigate how the use of more sustainable active transport modes can be increased.A factor and cluster analysis was conducted to identify coherent groups of participants that are similar to each other regarding psychological determinants of travel mode choice, but different from participants in other groups. Two clusters of participants with similar psychological determinants of travel mode choice were identified. The difference between both clusters was mostly explained by cycling related factors. As a result, a clear ‘pro-cycling’ cluster was identified (55.6% of participants in the sample), consisting of people with more favourable cycling-related factors, and a ‘non-pro-cycling’ cluster of people with less favourable cycling-related factors. This suggests that the psychological determinants of cycling have a higher level of variation compared to the psychological determinants of walking. In other words, respondents’ answers related to cycling are more diverse than answers related to walking, or alternatively, people’s feelings related to cycling are more ‘pronounced’ than those related to walking.Significant differences in respondents’ characteristics are identified between both clusters. Higher shares of respondents from Groningen, Tilburg, Ghent and Düsseldorf are found in the pro-cycling cluster, while this cluster contains a lower fraction of respondents from Bergen, Liège and Trondheim. In addition, the pro-cycling cluster contains more young people (aged 18-34), more men and higher-educated, and more people living with a partner and children. They possess a higher number of all types of vehicles (including PeTs), except cars. The pro-cycling cluster also contains a higher share of respondents with a season ticket for public transportation and to a car or bike sharing system. The pro-cycling cluster contains fewer people who have difficulties to park a bicycle at home. Respondents in the pro-cycling cluster logically cycle significantly more often, but they also show higher rates of walking, riding a moped or motorbike, taking a taxi and using a PeT.CEDR call 215 - User Needs in a Multimodal Contex

Defining and applying surrogate safety measures and behavioural indicators through site-based observations

This dissertation looks into surrogate safety measures and behavioural indicators that are collected through site-based observations. Surrogate safety measures are defined as measurements that are used to describe the relationship between two road users in a traffic event for the purpose of quantifying the crash probability and/or the potential crash severity in a meaningful way. The main goal of this dissertation is to contribute to filling methodological knowledge gaps in site-based observations of surrogate safety measures and road users’ behaviour, and to investigate how such observations can be used to study road safety issues for which crash data appear to be less suitable.The dissertation includes a scoping review that investigates in a comprehensive and quantitative way how surrogate safety measures have been applied so far. The theoretical framework and first implementation of a new indicator, Extended Delta-V, are presented. Three case studies have been conducted that aim to further investigate how site-based observations of road users’ behaviour and interactions could supplement or even replace surrogate safety measures, especially when severe events take place infrequently and/or dispersed. The case studies relate to: 1) the safety of bicyclists on bus lanes shared with bicyclists, 2) drivers’ behavioural adaptions caused by wind turbines alongside the roadway, and 3) differences in drivers’ interactions at right-hand priority intersections and priority-controlled intersections. The case studies provide some safety-relevant insights into topics that have rarely been addressed in scientific literature before. Policy and design implications are discussed

In search of surrogate safety indicators for vulnerable road users : a review of surrogate safety indicators

Surrogate indicators are meant to be alternatives or complements of safety analyses based on accident records. These indicators are used to study critical traffic events that occur more frequently, making such incidents easier to analyse. This article provides an overview of existing surrogate indicators and specifically focuses on their merit for the analyses of vulnerable road users and the extent to which they have been validated by previous research. Each indicator is evaluated based on its ability to consider the collision risk, which can be further divided into the initial conditions of an event, the magnitude of any evasive action and the injury risk in any traffic event. The results show that various indicators and their combinations can reflect different aspects of any traffic event. However, no existing indicator seems to capture all aspects. Various studies have also focused on the validity of different indicators. However, due to the use of diverse approaches to validation, the large difference in how many locations were investigated and variations in the duration of observation at each location, it is difficult to compare and discuss the validity of the different surrogate safety indicators. Since no current indicator can properly reflect all the important aspects underlined in this article, the authors suggest that the choice of a suitable indicator in future surrogate safety studies should be made with considerations of the context-dependent suitability of the respective indicator

The ‘safety in density’ effect for cyclists and motor vehicles in Scandinavia: An observational study

Safety in density (SID) potentially explains the safety in numbers (SIN) phenomenon by positing that ‘the SIN effect can be reproduced simply through encouraging behaviour that leads to the formation of higher-density cyclist groups’. The study further explores this hypothesis using event-based exposure, queues and groups of road users. Using three different definitions of encounters between road users, these were manually counted at signalized intersections, and their relationship to traffic volume was assessed. Based only on the frontmost motor vehicle in a queue and one cyclist among the several passing in front of that vehicle, the results show a less than linear relationship between meetings and trafficvolume. An in-crease in the number of cyclists entails a general increase in cyclists passing in front of each motor vehicle, and an increase in motor vehicles increases queue lengths. However, crash data from the Swedish accident database (STRADA) show that it is exceedingly rare for multiple cyclists to be injured in the same crash. Together with results from a crash-encounter model, this suggests that the SID hypothesis may help to ex-plain SI

In search of the severity dimension of traffic events: Extended Delta-V as a traffic conflict indicator

Most existing traffic conflict indicators do not sufficiently take into account the severity of the injuries resulting from a collision had it occurred. Thus far, most of the indicators that have been developed express the severity of a traffic encounter as their proximity to a collision in terms of time or space.This paper presents the theoretical framework and the first implementation of Extended Delta-V as a measure of traffic conflict severity in site-based observations. It is derived from the concept of Delta-V as it is applied in crash reconstructions, which refers to the change of velocity experienced by a road user during a crash. The concept of Delta-V is recognised as an important predictor of crash outcome severity.The paper explains how the measure is operationalised within the context of traffic conflict observations. The Extended Delta-V traffic conflict measure integrates the proximity to a crash as well as the outcome severity in the event a crash would have taken place, which are both important dimensions in defining the severity of a traffic event. The results from a case study are presented in which a number of traffic conflict indicators are calculated for interactions between left turning vehicles and vehicles driving straight through a signalised intersection. The results suggest that the Extended Delta-V indicator seems to perform well at selecting the most severe traffic events. The paper discusses how the indicator overcomes a number of limitations of traditional measures of conflict severity. While this is a promising first step towards operationalising an improved measure of traffic conflict severity, additional research is needed to further develop and validate the indicator

Sharing is (s)caring? Interactions between buses and bicyclists on bus lanes shared with bicyclists

This paper presents the results of an observation study of interactions between bicyclists and buses on shared bus lanes. The aim of the paper is to analyse bicyclists' safety on bus lanes shared with bicyclists. Straight sections of two bus lanes shared with bicyclists in Belgium are observed. All interactions between bicyclists and buses over two full weeks are recorded and analysed. Additionally, the lateral position and riding speed of bicyclists that are in interaction with buses are compared with the behaviour of bicyclists that are not in interaction with buses. One of the observed bus lanes is in line with road design guidelines in a number of countries that state that a sufficiently narrow bus lane (<3.5. m) is hypothesised to be safer than a somewhat wider bus lane; the other observed bus lane is deemed too wide according to these guidelines and is hypothesised to lead to close overtaking manoeuvres.The results show that close interactions between bicyclists and buses are relatively frequent on both types of analysed bus lanes. Close overtaking manoeuvres (a bus overtakes a bicyclist with a lateral distance less than 1. m) as well as close bicycle-following situations (a bus drives behind a bicyclist with a time gap less than 2. s) are quite common on both analysed bus lanes. The analyses could not confirm the hypothesis that a sufficiently narrow bus lane is safer than a wider bus lane. On the contrary, close interactions seem even slightly more common on the narrower bus lane. Slightly more close overtaking manoeuvres take place on the narrower bus lane, but the difference is not statistically significant. Additionally, more bicycle-following situations take place on the narrower bus lane because overtaking is more difficult. The results show that buses often maintain a close time gap in these situations. The overtaking speed of the buses is, however, significantly higher on the wider bus lane compared to the narrower one.Moreover, the presence of a bus has an influence on the behaviour of bicyclists. Bicyclists who get overtaken by a bus ride more closely to the edge of the road than bicyclists who are not in interaction with a bus. While the road design guidelines assume that bicyclists take up a width of one meter from the edge on bus lanes shared with bicyclists, the observations show that bicyclists take up much less space while being overtaken. The presence of a bus does not have a significant influence on the standard deviation of the lateral position of the bicyclist. On the narrower bus lane, some findings suggest that bicyclists who are involved in an interaction with a bus ride faster than bicyclists who are not involved in an interaction with a bus