Wildlife & Traffic

A European Handbook for Identifying Conflicts and Designing Solutions

10 Maintenance of ecological assets on transport linear infrastructure
New chapter (2020). In cooperation with CEDR Transnational Road Research Program ‘Roads and Wildlife’
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10.3. Maintenance requirements for ecological asset and wildlife management

10.3.1 General recommendations

Maintenance practice for each ecological asset should be based on guidelines included in maintenance plans (see section 10.2) and are summarised below.

- Perform a detailed inventory of elements to be inspected and maintained, including it a GIS database. Include data about geolocation, features (dimensions, materials, etc.) as well as targets, standards and goals to be met. All information recorded in the inspections and maintenance tasks should be comprehensively recorded in the database, which should also have scope to record any particular incident and/or modification to resolve problems or All elements of each asset should be included in the inventory and the maintenance plan

- Undertake the inspection and maintenance tasks for each element according to the infrastructure plan and respective national guidelines and

- Schedule the inspection and maintenance tasks appropriately to keep to specifications provided by designers and constructors, and according to weather events, biological events (e.g. seasonal migration or periods when target species movements are increased; seek wildlife expert assistance for schedules of target species) or any extraordinary event, such as infrastructure maintenance

- Set the general qualitative or quantitative standards to be met, according to target species, for all components of each ecological

- Establish and apply procedures for identifying conflicts or deviation from standards and how to resolve them: repair, reinforce or

- Develop appropriate training for maintenance staff and field

- Monitor, evaluate and report successes, needs and conflicts experienced during maintenance, in order to correct deviations and include this information in future plans.

- Modify the maintenance practice and plan according to results, information gathered and any species creating conflicts or experiencing negative effects. Define and schedule additional actions if conflict increases or expands.

The overall guidelines for inspecting, preserving, and improving each asset are provided in the following sections and specific descriptive task sheets are included in section 10.4.

10.3.2 Maintenance of wildlife fences and screens

Well designed, installed and maintained, fences prevent wildlife getting onto roads and railways, reducing roadkill and road traffic accident risks. Fences must also guide animal movements towards entrances of fauna passages or any transversal crossing structures.

Screens are installed to reduce disturbances from traffic (light or noise) at wildlife passages or on road stretches with sensitive adjacent habitats. They may also help funnel bird and bat flight to suitable crossing structures. In all cases they must be clearly visible to avoid bird collisions.

Wildlife fences and screens must be regularly inspected and maintained to ensure their long-term performance. Repeated damage by fauna or vandalism at particular locations could require a change of design.

All fencing components (mesh, wires, poles, escape devices and cattle grids, where applicable) and all type of screens (e.g. noise barriers, and screens to funnel bird and bat flight) should be included in the inventory and the maintenance plan.

The following descriptive maintenance task sheets are provided in section 10.4.

Maintenance of fencing: meshes and poles

Maintenance of fencing: escape devices

Maintenance of cattle grids

Maintenance of screens

Maintenance of amphibian/small fauna fences

10.3.3 Maintenance of wildlife crossing structures

Wildlife crossings (also named fauna passages) are transversal structures located under or over the linear transport infrastructure constructed or modified to provide safe crossing points for animals and/or to connect habitats on both sides of the linear infrastructure. Main types of wildlife crossings are:

- Ecoducts (green/landscape bridges)

- Wildlife and multi-use overpasses

- Canopy bridges (tree-top overpasses)

- Viaducts

- Wildlife and multi-use underpasses

- Modified culverts

- Amphibian tunnels

Wildlife crossings must be regularly inspected and maintained to ensure their long-term performance. Structural points as well as ecological features related to soil, vegetation, wildlife refuges or human uses could have a major effect on fauna passage effectiveness and must be appropriately maintained. Land uses and environmental changes in adjacent areas may also radically modify their use by wildlife.

All types of wildlife crossing, including under and overpasses and culverts modified to enhance wildlife use should be included in the inventory and the maintenance plan. Maintenance tasks may vary widely according to the type of structure and must be based on standards provided in the project (see Box 3).

Some passages are specific for wildlife, while others are multi-use and combine wildlife crossing with drainage, cattle routes, pedestrian paths, or even low-intensity traffic roads. Cooperation with water, environmental and land planning authorities, as well as other local stakeholders, is crucial to guarantee their conservation and could assist in reducing maintenance costs.

Special structures, such as big landscape bridges (ecoducts), could require particular management involving local stakeholders. Those structures located in Natural Protected Areas, ecological corridors or with endangered target species should be prioritised and will require additional ecological monitoring by wildlife experts to verify the achievement of their goals.

The following descriptive maintenance task sheets are provided in section 10.4.

Maintenance of ecoducts, wildlife and multi-use overpasses

Maintenance of viaducts, wildlife and multi-use underpasses

Maintenance of modified culverts

Maintenance of amphibian tunnels

10.3.4 Maintenance of wildlife warning signs

Wildlife warning signs aim to prevent AVC by influencing driver awareness and behaviour. The effectiveness of signs reduces if drivers become accustomed to them and don’t heed the warning. This problem arises when wildlife warning signs are overused or are not adapted to hazardous road sections. To solve these problems, road operators use various types of awareness signs, and complement them with reinforced warning messages such as reflective or illuminated panels, temporary signs activated only during conflictive periods, or those activated by Animal Detection Systems (ADS).

Appropriate maintenance of all types of wildlife awareness signs (standard, reinforced, temporary or activated by ADS) to ensure they function correctly is crucial to maintain their effectiveness. The correct location of signs corresponding to conflictive road sections identified is also a key factor.

Activities must not only include inspecting, cleaning and repairing signs, but also the maintenance of electric and electronic components including sensor and energy supply elements. Relocating or even removing wildlife warning signs to adapt them to the AVC hotspots location is also part of the maintenance tasks.

Maintenance practice should be modified according to the results and information gathered. A periodic expert evaluation of AVC hotspots (see 3.7) is particularly important to determine if wildlife awareness signs are correctly placed or should be moved. Removal of signs should also be considered where there is no AVC risk in order to maintain the overall consistency of risk mitigation and to avoid drivers becoming desensitised to signs.

The effectiveness of wildlife awareness signs in announcing locations of risk may be enhanced by awareness campaigns organised to help drivers understand conflict and adapt their driving behaviour. The use of GPS apps which alert the location of wildlife awareness signs will also reinforce the understanding of the hazard and make drivers slow down.

The following descriptive maintenance task sheets are provided in section 10.4.

Maintenance of wildlife awareness signs

Maintenance of signs activated by Animal Detection Systems

10.3.5 Maintenance of verges and other green areas

The main goal for road verges and medians management is to meet standards for road safety. However, most of these elements can also provide aesthetic landscape value and habitats for wildlife. These green areas, including resting areas and other landscaped zones, help enhance Green Infrastructure when they are managed to promote and sustain benefits to biodiversity. Two basic principles apply when enhancing habitats for wildlife:

- Legal obligations for wildlife conservation such as European Directives on Habitats and Birds, require that maintenance tasks do not injure, kill or disturb the breeding sites of endangered species (see list).

- Conflicts with traffic safety and the creation of ‘ecological traps’, attracting animals to areas with high mortality risk, must be avoided with expert help to carefully select the areas where biodiversity could be enhanced and those where wildlife access should be avoided.

Soil and vegetation management is key to attracting or deterring target species because wildlife habitats are defined by those elements. Landscaped green areas along transport linear infrastructure may have positive, neutral, or negative effects depending on how they are designed and managed.

Activities included in green areas maintenance are soil management, sowing, planting, mowing, pruning, replacement, removal and any other task needed to conserve or improve the green area habitats. Maintenance of structures that provide refuges to target species should also be included. A task schedule must be planned considering road safety, climate, soil and vegetation conditions and to provide a mosaic of habitats with different features where they are needed. The schedule must also be adapted to the life- cycles of wildlife target species to avoid any damage during breeding and hibernation periods.

Landscaped area maintenance should include the definition of sections to be managed according to different goals and functions (to reduce hazards to traffic, to enhance wildlife, etc.) identifying stretches that will require different conditions according to these (see Box 4). Conditions established by road and environment regulations must be considered.

Control of invasive alien species (IAS) is a key task to be developed and appropriate maintenance could also provide an essential ecological function in combatting the effects of climate change such as the risks of forest fire spread or flooding.

Site conditions such as weather, ecosystems and target species present in the area will have a strong influence on vegetation management. Cooperating with ecologists will help adapt guidelines in this document to local conditions.

Main aspects to be considered for verge and median biodiversity-friendly management are listed in Box 5.

The following descriptive maintenance task sheets are provided in section 10.4.

Vegetation management

Maintenance of habitats for pollinators and other small fauna

Control of invasive alien species (IAS)

Reducing forest fire risk

10.3.6 Maintenance of ponds and other drainage elements

Drainage systems in roads and railways include perimeter ditches, retention ponds, culverts, and other transversal structures. Ensuring standards for water evacuation and road safety through drainage systems can be combined with enhancing biodiversity by providing habitats for wildlife. Ponds and ditches can host invertebrates and fish, attract amphibians to breed and provide shelter and food for insects, reptiles, mammals and birds. Two basic principles apply when enhancing aquatic habitats for wildlife:

- Legal obligations for wildlife conservation such as European Directives of Habitats and Bird, require that maintenance tasks do not injure, kill or disturb the breeding sites of endangered species (see list).

- Conflicts with traffic safety and the creation of ‘ecological traps’, attracting animals to areas with high mortality risk, must be avoided with expert help to carefully select the areas where biodiversity could be enhanced.

Drainage transversal structures such as culverts, open-span bridges and viaducts can also play a key role in ecological connectivity, providing links for wetlands, channels, rivers, and other aquatic elements of the Green Infrastructure. Drainage elements that can play a role as habitats for wildlife should be identified and specifications for management must be provided.

Maps of aquatic habitats in retention ponds, ditches and other elements of the drainage systems to be inspected and maintained, should be included in a GIS database. Management should be planned primarily to maintain the function of drainage and areas managed to enhance biodiversity should have particular specifications including standards to be met for all features in ponds and drainage elements (including water level variation, water quality, vegetation conditions, etc.).

Water, road and wildlife experts must work together to design successful drainage system maintenance practice.

Main aspects to be considered for drainage systems biodiversity-friendly maintenance are listed in Box 6.

The following descriptive maintenance task sheets are provided in section 10.4.

Management of retention ponds to host wildlife

See also

Maintenance of viaducts, wildlife and multi-use underpasses

Maintenance of modified culverts.

10.3.7 Animal-vehicle collisions (AVC) management

Road and railway traffic accidents involving large animals are increasing in many European regions. Removing carcasses is a significant task for maintenance crews, has health and safety implications and high economic costs. To appropriately record and analyse road traffic accidents involving animals is the basis for identifying hotspots of wildlife road mortality, factors increasing the risk, and the data thresholds at which action to reduce the AVC must be taken.

Investing in appropriate mitigation measures to avoid AVC is cost-effective practice in economic, social and environmental terms. A number of mitigation measures can be applied by road operators, such as improving or reinforcing fences, adapting existing transversal structures to be used by wildlife, and enhancing wildlife awareness signage based upon expert identification of conflict points and assessment of potential solutions.

AVC management should be based on the points listed below.

- Develop practice based on instructions for the whole AVC management process including searching, removing, recording data and undertaking regular expert analyses to determine conflictive road sections and take corrective action.

- Define and apply procedures for removal and destruction of carcasses, or any other treatment according to national Be aware that some animal health regulations could require specific management of carcasses, e.g. strict biosafety conditions exist for wild boar carcass management in regions affected by African Swine Fever.

- Use a system to record roadkill data which allows mitigation measures to be defined from the information (see Box 7). The data recorded from field crews collecting carcasses provides the key basic information. Periodic additional surveys conducted by wildlife experts are needed in sensitive areas crossing habitats with high risk of mortality of small animals (protected areas, river crossings, wetlands, etc.) which are not recorded during regular crew patrolling.

- Provide field crews with procedures and appropriate devices for accurately recording carcasses Other stakeholders may also provide data such as police, traffic authorities, conservation organisations, hunters, etc.

- Define and apply user friendly procedures for recording data about each animal carcass, which include time (date and hour), location (road code, coordinates of the point) and details about the animal (species, sex and age class: adult or juvenile) if known. Local conditions related to the infrastructure or the landscape which help understand why the accidents occur should also be recorded.

- Develop appropriate training for maintenance staff and field crews on data collection and carcass management (see section 10.2; step 5) including guides to identify the species.

- Request regular analyses of the data collected to identify road mortality hotspots, to be undertaken by experts (see Box 8).

- Define the problem: numbers, most affected species, most conflictive periods, etc. )

- Apply road accident clustering methods to identify sections where AVC are more frequent, e.g. KDE+ or any other which has the possibility to define a frequency threshold goal.

- Identify where, when and why accidents cluster using location-specific data as a basis for the definition of appropriate solutions.

- Set the general qualitative or quantitative standards to be met and thresholds of AVC frequency which can vary widely depending on target species and their numbers in the area. This permits identification of priority road sections where thresholds are breached and appropriate mitigation measures must be taken.

- Monitor, evaluate and report successes, needs and conflicts experienced during the management of wildlife road mortality, in order to include this information in future plans.

- Modify the maintenance plan and undertake corrective actions according to results and information gathered and to target species most frequently road Define and schedule additional actions to reduce conflicts (fencing combined with fauna passage, modification of verge and median conditions, etc.) if conflict increases or expands.

The following descriptive maintenance task sheets are provided in section 10.4.

Management of road killed animals

Management of animal-vehicle collisions (AVC) data