The prevention of animal-vehicle collisions (AVCs) and complying with environmental legislation are central tenets in the design, construction and operation of the 6 million kilometres of roads and railways across Europe. Equally important is the goal to reduce biodiversity loss which can also have a substantial benefit to human welfare.
Ecological assets in transportation infrastructure comprise of all the elements aimed at reducing wildlife hazards including traffic safety, the mitigation of negative impacts on nature, and the enhancement of biodiversity in areas associated with transportation networks.
These guidelines provide recommendations for undertaking appropriate maintenance of ecological assets to allow for the preservation of the integrity, function, and long-term performance of these assets (see Table 1). Two main types can be identified:

- Wildlife mitigation measures, to reduce AVC risk, to preserve ecological connectivity and to reduce disturbances caused by traffic to adjacent ecosystems. Main elements included are wildlife fences and screens, wildlife
crossings and wildlife warning signs.

- Habitats related to transportation infrastructure (HTI) hosting wild flora and fauna. Main elements included are verges and other green areas, ponds, and other drainage elements (aquatic habitats).

Table 1. Main ecological asset functions preserved by applying appropriate maintenance.

Ecological asset maintenance places special requirements on road and railway maintenance approaches:

- Legal obligations exist in relation to infrastructure crossing Natura 2000 sites, (Sites of Community Importance (SCI), Special Areas of Conservation (SAC), and Special Protection Areas (SPA)) and other areas hosting species or habitats included in Bird and Habitats Directive (see Appendix 1. Environmental regulations and strategies).

- Diverse local site conditions and wildlife characteristics require that the general instructions provided in these guidelines are applied in a flexible way depending on the specific features of the area which may change over time.

- Specialists with skills in wildlife management should be part of the maintenance staff, and cooperation with stakeholders involved in biodiversity, water or land management is required - a structured multidisciplinary approach.

- Monitoring and evaluation of the effects from different maintenance practices/regimes is particularly important to expand our knowledge and understanding on this topic in order to adapt current practice to changing
conditions.

By undertaking appropriate maintenance of ecological assets, infrastructure operators optimise investment in traffic safety, which in turn contributes to enhanced benefits for biodiversity and human welfare.
The main benefits provided are:

- Improve traffic safety and reduce the high social and economic costs of road traffic accidents involving wild animals.

- Comply with the environmental legislation for biodiversity conservation and the conditions of the infrastructure planning approval process.

- Reduce wildlife mortality and disturbances to adjacent ecosystems due to traffic and infrastructure features.

- Maintain ecological connections across transport linear infrastructure.

- Avoid the spread of invasive alien species (IAS).

- Support the measures installed or constructed to enhance biodiversity on ponds,verges, and other green areas.

- Reduce the effects of climate-related risk and extreme events such as floods and forest fires.

- Play a part in improving future design, construction, and maintenance practice of ecological assets, by providing feedback on lessons learned.

- Ensure value for money invested in ecological mitigation.