Glossary of Key Terms

This glossary provides definitions for key terms used throughout the Biodiversity & Infrastructure Handbook, supporting consistent understanding across disciplines such as ecology, engineering, transport planning and policy.

Definitions are based on legal texts, reference documents and expert agreement, and cover essential concepts related to wildlife and traffic, habitat fragmentation, ecological connectivity, mitigation measures, monitoring, green infrastructure and nature-based solutions. The glossary helps practitioners interpret technical guidance and supports clear communication between stakeholders involved in infrastructure projects.

If you are new to transport ecology or working in a multi-disciplinary team, the glossary can serve as a quick reference before exploring detailed handbook chapters. Terms will continue to evolve as the handbook is updated through expert collaboration and user feedback.

Last update: October 2023 – How to cite

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There are currently 12 names in this directory beginning with the letter W.
Waterway
A navigable body of water.
Weir
Construction in a river or canal designed to hold the water upstream at a certain level.
Wetland
Land or area containing high levels of soil moisture or completely submerged in water for either part or the whole of the year.
Wildlife
All wild animals, plants, fungi and bacteria collectively.
Wildlife corridor
Linear-shaped area or feature of value in facilitating wildlife movement across a landscape. See also ‘Ecological corridor’.
Wildlife crossing structure
See ‘Wildlife passage’.
Wildlife fencing
Fencing designed and erected specifically to prevent animals from gaining access onto infrastructure and to lead them to safe crossing points.
Wildlife overpass
Structure built over transport infrastructure specifically to provide a safe crossing point for wildlife and to connect habitats from both sides. The surface is covered with natural materials and soil allowing the growth of different species of vegetation. Other refuges for fauna such as stone or wood rows can also be installed. Combined with perimeter fencing that funnels the animals to the structure and with light/noise screens to reduce disturbance when required. While similar to landscape overpasses, they are narrower, limiting the extent to which different habitats and vegetation can be included on the structure. Synonym: 'Fauna overpass'. See also 'Landscape overpass'.
Wildlife passage
Structure designed to facilitate the safe movement of wildlife across linear transport infrastructure, located over or under the infrastructure. It can be specifically designed for wildlife use or modified to combine wildlife crossing with other uses such as drainage and other. Synonyms: ‘Wildlife crossing structure’, ‘Fauna passage’.
Wildlife underpass
Structure built under transport infrastructure specifically to provide a safe crossing point for wildlife, typically large and medium-sized mammals, such as ungulates and large carnivores, but also for other vertebrates and invertebrates. Construction types are predominantly box, vault or beam platform structures. The substrate is covered with natural materials and soil allowing different species of vegetation growth where there is enough light and humidity. Elements such as stone rows may provide wildlife refuges inside. Combined with perimeter fencing that funnels the animals to the structure and with light/noise screens to reduce disturbance when required. Synonym: 'Fauna underpass'.
Wildlife Vehicle Collisions (WVC)
See ‘Animal Vehicle Collision’.
Willingness-to-pay (WTP)
A term used in economics to quantify the maximum amount of consumption possibilities that an individual is prepared to sacrifice in order to consume a particular good. In many research projects, such as valuation of various environmental assets, the purpose is to estimate WTP in terms of money.