| 1. |
- Daniels, Stijn, et al.
(författare)
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Safety effects of dynamic speed limits on motorways
- 2016
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Konferensbidrag (refereegranskat)abstract
- Dynamic speed limits (DSL) are limits that change according to real-time traffic, road or weather conditions. In DSL-schemes road users are typically informed of speed limit changes by electronic signs that are housed within gantries situated above lanes. Dynamic speed limit systems are increasingly applied worldwide, usually on motorways. One of the objectives of dynamic speed limits is to improve traffic safety through reductions in speed variations within and across lanes and between upstream and downstream flows. This paper shows the results of an empirical evaluation of the effects on traffic safety of a dynamic speed limit system on motorways in Flanders, Belgium. The evaluation was done by means of a before-after analysis of crashes, completed with a cost-benefit analysis. The results show that the number of injury crashes decreased significantly (-18%) after the introduction of the system. A separate analysis for serious and fatal injury crashes revealed a non-significant decrease of 6%. A distinction according to crash type showed an almost significant decrease of 20% in the number of rear-end crashes whereas the number of single-vehicle crashes decreased by 15% (ns). However, no effect was found for side crashes. In addition to the analysis of the effects, a cost-benefit analysis was applied. The costs of the implementation of these systems were compared with the benefits of crash prevention. The cost-benefit analyses of the crash effects showed a benefits-to-costs ratio of approximately 0.7, which means that the costs tend to exceed the benefits. Taking into account the important margins of uncertainty with respect to both costs and benefits, we have also explored how the net benefits are affected by some key assumptions. The general conclusion is that there is no convincing evidence that the costs of the system currently outweigh the expected benefits in terms of crash prevention.
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| 2. |
- De Ceunynck, Tim, et al.
(författare)
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Sharing is (s)caring? Interactions between buses and bicyclists on bus lanes shared with bicyclists
- 2017
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Ingår i: Transportation Research Part F: Traffic Psychology and Behaviour. - : Elsevier BV. - 1369-8478. ; 46, s. 301-315
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 3. |
- Laureshyn, Aliaksei, et al.
(författare)
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In search of the severity dimension of traffic events: Extended Delta-V as a traffic conflict indicator
- 2017
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Ingår i: Accident Analysis & Prevention. - : Elsevier BV. - 1879-2057 .- 0001-4575. ; 98, s. 46-56
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 4. |
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| 5. |
- Martensen, Heike, et al.
(författare)
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The European Road Safety Decision Support System on Risks and Measures
- 2019
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Ingår i: Accident Analysis and Prevention. - : Elsevier BV. - 0001-4575. ; 08:05, s. 344-351
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Tidskriftsartikel (refereegranskat)abstract
- The European Road Safety Decision Support System (roadsafety-dss.eu) is an innovative system providing the available evidence on a broad range of road risks and possible countermeasures. This paper describes the scientific basis of the DSS. The structure underlying the DSS consists of (1) a taxonomy identifying risk factors and measures and linking them to each other, (2) a repository of studies, and (3) synopses summarizing the effects estimated in the literature for each risk factor and measure, and (4) an economic efficiency evaluation instrument (E3-calculator). The DSS is implemented in a modern web-based tool with a highly ergonomic interface, allowing users to get a quick overview or go deeper into the results of single studies according to their own needs.
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| 6. |
- Pirdavani, Ali, et al.
(författare)
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Measuring the association of socioeconomic neighbourhood characteristics with traffic safety performance
- 2016
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Konferensbidrag (refereegranskat)abstract
- Increasing evidence suggests that neighborhood-based measures of socioeconomic status are correlated with traffic injury. The main objective of this study is to determine the differences in associations between predictive variables and injury crashes (i.e. including injury and fatal crashes). To this end, crash data, socio-demographic, socioeconomic characteristics and road network variables are collected at the neighborhood-level and categorized by different genders and transport mode; “car driver”, “car passenger” and “vulnerable road users” (i.e. pedestrians and cyclists). In this study an activity-based transportation model called FEATHERS (Forecasting Evolutionary Activity-Travel of Households and their Environmental RepercussionS) is utilized to produce exposure measures. Exposure measures are in the form of production/attraction trips for several traffic analysis zones (TAZ) in Flanders, Belgium. Analyzing crashes at a neighborhood- level provides important information that enables us to compare traffic safety of different neighborhoods. This information is used to identify safety problems in specific zones and consequently, implementing safety interventions to improve the traffic safety condition. This can be carried out by associating casualty counts with a number of factors (i.e. developing crash prediction models) which have macro-level characteristics, such as socio-demographic and network level exposure. The results indicate that socioeconomic variables are differently associated with casualties of different travel modes and genders. For instance, income level of residence of a TAZ is a significant predictor of male car driver injury crashes while it doesn’t significantly contribute to the prediction of female car driver injury crashes.
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| 7. |
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| 8. |
- Varhelyi, Andras, et al.
(författare)
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Road Safety Management at Work Zones : Final report
- 2019
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Accidents nearby work zones are a persistent road safety problem in many European countries. The Conference of European Directors of Roads (CEDR) has initiated and finances the IRIS project (Incursion Reduction to Increase Safety in road work zones) with the aim to collect and share information about best practices in temporary traffic management at road works. An analysis of work zone accidents and a review of best practices were made. Psychological issues to improve safety at work zones were studied by a literature review. Interviews with stakeholders were carried out in eight European countries to gather information on guidelines, standards and procedures in temporary traffic management. Best practice findings cover organizational/management issues, work zone safety reviews, establishment/de-establishment of a road work zone, informing/warning and guiding road users through work zone areas, speed management, protecting devices for road workers’ and road users’ safety and incursion warning systems.
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| 9. |
- Varhelyi, Andras, et al.
(författare)
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Safety management at road work zones : Best-practice recommendations.
- 2020
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Ingår i: Proceedings of the Transport Research Arena TRA 2020 conference "Rethinking transport Towards clean and inclusive mobility" Helsinki, Finland.. ; , s. 1-9
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Konferensbidrag (refereegranskat)abstract
- Accidents nearby work zones are a persistent road safety problem in many European countries. The Conferenceof European Directors of Roads (CEDR) has initiated and finances the IRIS project (Incursion Reduction toIncrease Safety in road work zones) with the aim to collect and share information about best practices in temporarytraffic management at road works. An analysis of work zone accidents and a review of best practices were made.Psychological issues to improve safety at work zones were studied by a literature review. Interviews withstakeholders were carried out in eight European countries to gather information on guidelines, standards andprocedures in temporary traffic management. Best practice findings cover organizational/management issues,work zone safety reviews, establishment/de-establishment of a road work zone, informing/warning and guidingroad users through work zone areas, speed management, protecting devices for road workers’ and road users’safety and incursion warning systems.
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