The management and mitigation of the impact of linear infrastructures (roads, railroads, power lines etc.) can cover very different aspects, including environmental planning, population management, urbanistic aspects etc., regarding which a vast range of literature is available (link alla sezione delle pubblicazioni).
The direct impacts of roads, in terms of road mortality and fragmentation can be effectively addressed by a set of practical measures, which are summarized in the figure below All the specific solution presented should be only a part of a more general strategy to reduce the impacts of linear infrastructures on biodiversity.
Fom: ‘Wildlife and Traffic: A European Handbook for Identifying Conflicts and Designing Solutions’. By courtesy of Infrastructure & Ecology Network Europe (IENE).
Besides these technical interventions public awareness raising activities are of fundamental importance. It is common knowledge that one of the main causes of direct wildlife mortality on roads is the inadequate driving behavior of traffic participants.
For this all over the world a big range of different wildlife warning signs for drivers have been designed and installed on roads. However, in most of the cases they seem to be not sufficiently effective to really make drivers slow down.
It is therefore necessary, and one of the main objectives of the LIFE SAFE-CROSSING project, to develop high-impact panels to raise the awareness and level of attention of drivers in order to cause a major awareness of the potential danger. Click here to learn more.
Below we summarize the principal measure to reduce wildlife mortality.
They are an effective way to prevent animals accessing roads or railways but they have the disadvantage to strongly increase the barrier effect. The type of fence to be installed depends on the target species. The most important features to consider is the height, the size of the mesh, the poles, and for sure the materials to be used. Particular attention must be given to the maintenance of the fence. Fences can also be used on shorter segments in order to lead animals towards crossing structures such as ecoducts, underpasses etc.
These devices are installed at regular intervals on the road sides and are triggered by the headlights of passing vehicles. They have the advantage to be quite cheap and they do not represent a permanent barrier for wildlife, since the animals are warned only when there is a danger. However, in the technical scientific world there is still no clear agreement on the real effectiveness of these types of tools. Also, their maintenance is demanding. In the recent year an evolution of these devices are the warning active reflectors as the one will be implemented in the LIFE SAFE CROSSING PROJECT. In these devices the lights and sound are activated by a sensors triggered by the headlights of the vehicle. The results obtained seem quite interesting.
This system is used mainly for ungulates. A mix of substances are applied to posts near the roads in order to prevent animal crossings. One of the disadvantage is that the repellents must be often renewed, and there is the risk of habituation as for the previous device
Warning signs for drivers
One of the aspects of the aspect involved in the animal vehicle collisions is the driving behaviour. Traditional warning signs are placed in the most risky areas in order to increase the attention of drivers. The problem is that the widespread diffusion of the traditional warning signs makes them ineffective. Warning signs with flashing lights can be more effective, but if they are always in function after a certain period the drivers don’t pay attention to them.
Special road panels are sometimes used but there are some restrictions due to legislation and they can be considered only an accompanying measure of other techniques
Wildlife warning signs with sensors
In order to avoid driver habituation in the recent years are most often used warning signs that are triggered by sensors placed near the road to detect the animal presence. In this way these signals are activated only when there is the presence of the animals. This system requires technical maintenance and can be applied only on limited road segments.
A more sophisticated approach to face the problem of animal vehicle collision is the system developed in the LIFE STRADE project and now implemented in THE LIFE SAFE CROSSING. This system aims to act simultaneously on the drivers and the animals as shown here.
Wildlife crossing structures
Ecoducts, overpasses, underpasses and culverts are structures that allow the animals to pass over or under the roads or railroads, and therefore represent a very effective way to reduce habitat fragmentation. These are either preexisting infrastructures such as maintenance tunnels under the roads, or simple bridges, or they are specifically constructed, such as ecoducts. Certainly the construction of such infrastructures is very demanding in terms of costs and administrative procedures. The crossing structures can be accompanied by interventions such as adaptation of the vegetation to lead the animals towards the structures, or the construction of fences. In some circumstances it can be important to adapt the existing infrastructures built for other purposes. This intervention is economically profitable and very effective for the wildlife conservation.
An important measure to reduce wildlife mortality due to traffic accidents it is the correct management of the vegetation along the sides of the road. For example the cutting of vegetation can reduce the attractiveness of the roadsides for different wildlife species and increase the visibility of the drivers. At the same time particularly attention should be given to the plant species to be planted near the roads in order not to use the ones which can be an attractive for the animals.
In order to select the most appropriate intervention to be implemented it’s important to base the choice on a detailed monitoring program.
Monitoring programs and subsequent data analysis should be fundamental to define the priority areas, and once an intervention has been implemented it’s essential to monitor it’s effectiveness.