Road Crossing Structures Important In Reduction Of Animal Mortality On Roads

Researchers from the Department of Ecology at the Autonomous University of Madrid and the CEDEX (Ministry of Public Works) have spent several years studying how various animal species use the wildlife walkways and other structures that enable them to cross highways. According to the scientists, these crossings, which may be specifically designed for the purpose, or have mixed use (drains, subways and bridges) reduce traffic accidents through collisions with animals.

“The effectiveness of these structures is a key feature in wildlife conservation, particularly bearing in mind the relentless growth of communication networks, which is leading to an increasingly fragmented countryside, full of barriers to wildlife that are at times impossible to cross,” Cristina Mata, researcher at the Autonomous University of Madrid, told SINC.

The study, published in the most recent issue of the Journal of Environmental Management, has enabled an evaluation to be carried out of the design of structures that stop animals crossing the tarmac and reduce the accident rate on Spanish roads. According to data from the Directorate General of Traffic (DGT), there were 10,000 traffic accidents caused by collisions with animals on roads in 2006 alone, resulting in 1,000 human injuries and 23 deaths.

Of the 43 structures analysed using digital photography techniques and other more traditional means, such as footprints left on a powdered marble surface, the tracks of 424 different animals were recorded between the months of March and June 2001. Mata says that this “shows how the construction of walkways specifically for the use of wildlife is justified, while the adaptation of drains or increasing the size of existing structures should also be borne in mind because of the attraction of these structures for certain species and their relatively low cost”.

The work was carried out on part of the A-42 highway between Camarzana de Tera (km 34, in the province of Zamora) and Orense (km 217). This four-lane road is fenced along its length and was opened to traffic in 1998. It is used each day by about 4,500 vehicles, 23% of them lorries, which could endanger the lives of vertebrate populations living in the area.

A solution to reduce accidents involving wild boar and deer

Lizards, snakes, small rodents such as mice, shrews, moles and rats, Iberian hares, weasels, wild cats, wolves and dogs are among the animals identified, as well as wild boar and deer. On average, the researchers registered 0.99 animal tracks per day during the study period.

The results show that 17 different animal species use the structures that cross the road. One of the most commonly recorded in all the various structures were foxes, with an average of 0.27 crossings per day. Other species such as badgers also showed high usage. The results obtained for wild boar, as well as for roe deer and other deer, support the importance of building large crossing points specifically designed for these animals.