Catharinus F. Jaarsma

Using traffic flow theory to model traffic mortality in mammals

Traffic has a considerable effect on population and community dynamics through the disruption and fragmentation of habitat and traffic mortality. This paper deals with a systematic way to acquire knowledge about the probabilities of successful road crossing by mammals and what characteristics affect this traversability. We derive a model from traffic flow theory to estimate traffic mortality in mammals related to relevant road, traffic and species characteristics. The probability of successful road crossing is determined by the pavement width of the road, traffic volume, traversing speed of the mammals and their body length. We include the traversability model in a simple two-patch population model to explore the effects of these road, traffic and species characteristics on population dynamics. Analysis of the models show that, for our parameter ranges, traffic volume and traversing speed have the largest effect on traffic mortality. The population size is especially negatively affected when roads have to be crossed during the daily movements. These predictions could be useful to determine the expected effectiveness of mitigating measures relative to the current situation. Mitigating measures might alter the road and traffic characteristics. The effects of these changes on traffic mortality and population dynamics could be analysed by calculating the number of traffic victims before and after the mitigating measures.

Reducing habitat fragmentation by minor rural roads through traffic calming

The rural road network suffers continually from ambiguity. On the one hand, the presence of this network and its traffic flows offer accessibility and make a contribution to economic development. While on the other, its presence and its traffic flows cause fragmentation. The actual ecological impact of this fragmentation depends on several variables such as species and road characteristics. This paper focuses on minor rural roads. The spatial concept developed to address this, ‘traffic calming rural area’ (TCRA) is intended to address both accessibility and sustainable environment. It does this by concentrating the current diffuse traffic flows on a few rural highways, thus, creating rural residential areas within the region. This paper presents some formulae to quantify the resulting fragmentation. A more practical method compares the sizes of continuous landscape units. Both the formulae and the method have been used for two pilot studies. The results indicate that implementing the TCRA concept leads to larger continuous landscape units, thereby helping to reduce fragmentation effects. # 2002 Elsevier Science B.V. All rights reserved.

Approaches for the planning of rural road networks according to sustainable land use planning.

Sustainable land use planning creates a great challenge for rural road network planning. Further improvements of the network are a necessity, to provide for peoples needs in the (near) future. Simultaneously, harmful effects of this network conflict with the principles of sustainability. So, there is a need for a new planning approach, serving interests of both accessibility and a sustainable environment. The spatial concept of the traffic-calmed rural area (TCRA) is presented as a solution to this dilemma. This concept concentrates on the present diffused flows on minor rural roads at a few rural highways, which resulted in a decrease of volumes and speeds within the region.

Modeling the Effect of Traffic Calming on Local Animal Population Persistence

A steady growth in traffic volumes in industrialized countries with dense human populations is expected, especially on minor roads. As a consequence, the fragmentation of wildlife populations will increase dramatically. In human-dominated landscapes, typically minor roads occur in high densities, and animals encounter them frequently. Traffic calming is a new approach to mitigate negative impacts by reducing traffic volumes and speeds on minor roads at a regional scale. This leads to a distinction between roads with low volumes as being part of the traffic-calmed area, whereas roads with bundled traffic are located around this area. Within the traffic-calmed area, volumes and speeds can be decreased substantially; this is predicted to decrease the disturbance and mortality risk for animals. Thus far, data on the effects of traffic calming on wildlife population persistence remain scarce. Using metapopulation theory, we derived a model to estimate thresholds in the size of traffic-calmed areas and traffic volumes that may allow persistent populations. Our model suggests that traffic calming largely increases the persistence of roe deer in a landscape with a dense road network. Our modeling results show trade-offs between traffic volume on roads within the traffic-calmed area and both the area of habitat available for this species in the traffic- calmed area and the size of the traffic-calmed area. These results suggest ways to mitigate the fragmentation of wildlife habitat by road networks and their expected traffic volumes.

Counting of visitors in the Meijendel dunes, The Netherlands

Accurate and sufficiently detailed information about recreation-related use of dune areas is necessary for their management. Long-term monitoring can provide this information. This paper presents the visitor counting programme used in the Meijendel dune area since 1992. The data collected during the first ten years are used to evaluate the method. The combination of mechanical vehicle counts and additional visual counts proved to be reliable and produced an accurate data set. Costs could be reduced through eventually reducing the number of counting locations and limiting the number of visual counts.

Model for rural transportation planning considering simulating mobility and traffic kills in the badger Meles meles

Large-scale spatial planning requires careful use and presentation of spatial data as it provides a means for communication with local stakeholders and decision makers. This is especially true for endangered species, such as the badger (Meles meles) in the Netherlands. To effectively mitigate the badgers traffic mortality in an area, two types of tools are needed. The first one estimates the probability of a successful road crossing for individual animals. The second tool is GIS-based and not only models the movement patterns of animals but also estimates an animals daily number of road crossings. With data on population size as well as on road and traffic characteristics, a combination of both tools provides a measure of the mortality risk roads pose to wildlife in an area. Such estimations proved to be invaluable in a planning process with local inhabitants in the municipality of Brummen (the Netherlands), where ecological as well as safety problems appear. Our study demonstrates the applicability of GIS tools in balancing ecological consequences of road network options with a different distribution of traffic flows over the area in spatial planning and ecology.

Passing bays for slow moving vehicles on rural two-lane roads

Abstract Slow‐moving vehicles, including agricultural vehicles, on arterial highways can cause serious delays to other traffic as well as posing an extra safety risk. This paper elaborates on a small‐scale solution for these problems: the passing bay. It investigates the impacts of a passing bay on the total delay for other motorized vehicles, the number of passing manoeuvres and hindered vehicles, and the mean delay per hindered vehicle. The latter is also considered to be an indicator for traffic safety. The calculations are performed for two characteristic trips with a slow‐moving vehicle. The passing bay is an effective solution to reducing delays on arterial highways when two‐way hourly volumes exceed 600–1000 vehicles. The effects depend on the trip length and speed of the slow‐moving vehicle, and on the passing sight distance limitations of the road. A distance of 2–4 km between the passing bays seems an acceptable compromise between the reduction of delay for other motorized vehicles and the extra discomfort and delay for drivers of slow‐moving vehicles. This result also shows that passing bays are not effective in regions where slow‐moving vehicles mainly make trips shorter than this distance.

Traffic Mortality, Analysis And Mitigation

This chapter focuses on the impact of transportation on wildlife. Measures are frequently applied to mitigate these impacts. Most measures involve technical devices that change the road characteristics. However, also other measures may reduce traffic mortality, such as reduction of traffic volume or speed, and periodic closing of roads. For effectively applying these mitigating measures, insight in the effects of road and traffic characteristics on traffic mortality is needed. We argue that the success of measures that mitigate habitat fragmentation by roads drastically increases when minor roads are integrated in transportation planning. We discuss a strategy based on the concept “traffic-calmed rural areas”, where the effects of minor and major roads are not mitigated separately, but in coherence. To enable transportation planning to include the impacts on wildlife in the planning process, we present a traversability model derived from traffic flow theory that can be used to determine the probability of successful road crossings of animals based on the relevant road, traffic, vehicle and species characteristics. We apply this model in a case study in The Netherlands to evaluate different scenarios. Several levels of traffic calming are compared with the autonomous development, which shows that traffic calming can drastically reduce traffic mortality.

Landscape Ecology and Rural Roads: Traffic Calming for improving both landscape and wildlife?

Abstract Jaarsma C.F., van Langevelde F., Beunen R.: Landscape ecology and rural roads: Traffic calming for improving both landscape and wildlife? Ekologia (Bratislava), Vol. 32, No. 4, p. 352-360, 2013. The concept of traffic calming has successfully improved road safety. This concept applied in rural areas has provided new insights in the mitigation of negative effects of roads and traffic. Earlier studies have shown that the concept, distinguishing between local access roads and rural arterial highways, can also improve landscape connectivity for wildlife. Physical speed-reducing devices are frequently used in the context of traffic calming, but applying these devices may negatively impact the coherence and identity of the landscape. Therefore an alternative approach for speed reduction has been proposed, namely applying local landscape elements (such as hedgerows), plantings and objects of cultural heritage (such as railings of small bridges over local water courses) as speed-reducing devices. We explain this ‘green approach’ with examples from Dutch practice. We conclude that a combination of disciplines is needed to realize this new approach, which may be more cost-effective than the traditional approach and additionally improve the landscape quality. The new insights are at least equally effective from a landscape ecological viewpoint.

Local Collectors Versus Major Infrastructural Works

Cohesion between city and surrounding area is essential in the metropolitan landscape. However, this relationship is under strain. Firstly, the infrastructures, which are difficult to cross, are concentrated in exactly the transition zones of city and countryside, where — certainly for cyclists and pedestrians — the surrounding area is often difficult to reach from a residential area and vice-versa. Secondly, road users in the surrounding area are confronted with the loss of local connections because railways have been cleared of intersections or because new main infrastructure has been built. Current government policy considers this situation, but, in actuality, the focus is still too one-sided concentrating on construction costs and (railway) safety. A modification of this policy and a certain protection of local connections (including provisions for pedestrians and cyclists) within the framework of town and country planning are urgently needed. Because of the current developments, the metropolitan landscape is in danger of being divided into small ‘compartments’, which will only be connected by long indirect routes. A more integral approach and establishment of close-knit structures in Regional and Provincial Traffic and Transportation Planning Schemes can offer guarantees for more cohesion in the lowest categories of the road and path network.