January 4, 2013
By: Alejandro Baladrón Julian
High Speed Railways (HSRs) are a type of passenger rail transport that operates significantly faster than the normal speed of rail traffic. HSRs are spreading around the globe and eventually will be fully implemented in many industrialized countries. Currently, HSRs operate mainly in Europe, but they also exist in the U.S. (Northeast Corridor between Boston, New York and Washington, D.C.), Japan (the high-speed Shinkansen line), China (connecting Beijing-Hangzhou; Guangzhou-Wuhan and Shanghai – Nanjing), and other countries. High-speed lines in Europe, especially in France and Spain, have increased dramatically during the last 10 years. According to the High-Speed Rail Strategic Plan (2009), the U.S. is planning to invest in high-speed passenger rail network of 100 to 600 mile intercity corridors. Aligned with this plan, the California High-Speed Rail Authority is currently planning lines running from Sacramento to San Diego.
Although high-speed trains are clean and energy-efficient and therefore should be an environmentally friendly transportation system, the operational stage of HSRs can cause important environmental problems, including an increase in bird mortality.
The HSR infrastructures allow little flexibility in route design. In order to reach high speeds without derailing, HSR routes require straight trajectories and minimum slopes. As a result, HSRs cannot easily avoid intersecting areas of high bird density and endangered bird species. Furthermore, design constraints require aggressive constructive options such as the execution of viaducts (see Fig.1). These structures lead to a high probability in bird collisions as the flight trajectories of many species usually follows fluvial corridors or watercourses.
In addition to intersecting bird flight paths, birds are almost incapable of avoiding high speed trains when they approach. It has been observed that birds can barely avoid vehicles moving at higher speeds than 43.5-50 mph. In the case of HSRs, trains can reach up to 217 mph. A combination of high speeds with low running frequency of trains can produce high mortality rates of birdsas long periods of quietness make birds feel confident perched on or nearby the rail tracks.
Many groups of birds, including endangered species (see Fig.2), are vulnerable to HSRs (anatids, passerines, galliformes, diurnal and nocturnal birds of prey). Recently, two of the most dramatic cases of bird mortality were registered in Western Europe involving the Griffon Vultures (Gyps fulvus). In 2002, between the municipalities of Teba and Ronda (Malaga, South of Spain), a train killed 19 vultures, and in 2007, 37 vultures in Los Monegros (Huesca, North-East of Spain). In both cases, the vultures were eating dead animals from former collisions.
Are there solutions to address bird mortality caused by HSR?
As HSRs constitute a top priority investment in many countries banning them is not always a realistic option. However, it is clear that this is an environmental issue that can only get worse as the number of high-speed lines increases. Policy action is needed.
Policy 1. Speed reduction in Important Bird Areas (IBAs) crossed by HSR.
This policy requires trains to progressively reduce their speed before reaching Important Bird Areas (IBAs). However, the necessary speed reductions (and accelerations to recover speeds) jeopardize the functionality of the HSR system, increasing travel time and maintenance costs.
Policy 2. Corrective measures in IBAs and high-density bird areas: barriers and dissuasive techniques.
Placing barriers on both sides of the railway would force birds to raise their flight path and cross the railway above the train trajectory. Barriers can be concrete walls, plastic and metallic anti-collision shields, sand dikes, or tree plantations. The use of each of these types of barriers depend on various factors such as the risk of creating habitat fragmentation, the bird species affected, bird habitat use, and the associated cost. Dissuasive techniques can also help move birds away from collision areas. Bio-acoustic emitters have been proven efficient in dissuading herons from agricultural landscapes in Israel. However, the efficiency of these devices may decline after 3-6 weeks if they are not moved frequently.
Policy 3. Suppression of underperforming high-speed lines and funding re-allocation for corrective measures.
The third policy creates a ranking system of the expected passenger demand and the technical constraints to determine if all proposed HSRs should be constructed. For example, if a High-Speed Rail Strategic Plan allocates funding 30 new high-speed lines, the funds of the lowest ranked line could be used for corrective measures addressing bird collisions on the remaining 29 lines. Currently, there are a number of underperforming HSRs due to lack of passengers or technical constraints. Realistic estimates of the number of expected passengers and a careful analysis of the “full high-speed” potential of prospective high-speed corridors should help to establish a performance ranking. The ranking system, underperforming lines would not be constructed and the funding could be allocated for bird protection.
Why bird collision matters?
There are many reasons for policy action regarding bird collision. If HSR related bird collisions are not properly addressed, the number of critically endangered bird species may increase dramatically. An effective solution will require collaboration between wildlife supporters and HSR advocates. For the past two decades, the development of HSRs has been a controversial process between wildlife supporters, HSRs stakeholders, and governments trying to promote a faster commute between cities. Despite differences, today’s society recognizes the importance of protecting biodiversity as a high priority and the need to invest in species and habitat preservation to counterbalance wildlife decline, including birds.
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