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

All | # A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
There are currently 18 names in this directory beginning with the letter A.
Accompaniment measure
An intervention intended to be positive for biodiversity and ecosystem services, but not providing measureable gains that can be set against residual impacts. Accompaniment measures may or may not target the BES features significantly impacted by a project. Synonym: 'Addtional Conservation Actions'.
Adapted culverts
Modified pipe or box culvert that allows a watercourse and/or drainage to flow underneath transport infrastructure and includes adaptations to facilitate terrestrial wildlife crossing. These often include dry ledges or shelves to provide dry passage, which are connected to adjacent habitat. The design and landscaping at the entrances is particularly designed for the needs of wildlife, not only erosion control.
Adapted viaduct
Large structure, usually supported by pillars or arches, which carries transport infrastructure and enables the preservation of valuable ecosystems and ecological corridors below the structure. Preservation and restoration of continuous terrestrial, riparian and aquatic habitats below viaducts facilitate movement of multiple vertebrate and invertebrate species. Land uses and activities under the structure must be compatible with fauna movements and preservation of ecological connectivity. Viaducts must not be considered as wildlife passages when human disturbance or infrastructure with high traffic volume is beneath. Combined with perimeter fencing that funnels the animals to the structure and with light/noise screens to reduce disturbance when required. Synonym: 'Landscape underpass'.
Additional Conservation Actions
See 'Accompaniment measure'.
Additionality
A property of a biodiversity offset, where the conservation outcomes it delivers are demonstrably new and additional and would not have resulted without the offset. See also 'Offset'.
Agricultural (underpass or overpass)
Passageway across transport infrastructure to provide access to agricultural or forestry land, which may also be used by wildlife. See also ‘Forestry road’; ‘Cattle passage’.
Alien species
Animals and plants introduced accidentally or deliberately into a natural environment where they are not normally found. Such species can become invasive in their new environment if they start spreading and causing serious damage to native species and ecosystems. See also ‘Invasive Alien Species’.
Amphibian crossing
See 'Amphibian passage'.
Amphibian fencing
A continuous structure erected alongside infrastructure, designed to prevent amphibians from crossing and directing them to a specific crossing point. See also Amphibian crossing.
Amphibian passage
Small structures built under transport infrastructure designed specifically to provide a safe crossing point for amphibians. Often consisting of multiple underpasses in close proximity to each other. Requires effective opaque fencing to intercept the amphibians and funnel them to the crossing structures. Synonyms: ‘Amphibian crossing’; ‘Amphibian tunnel’.”
Amphibian tunnel
See ‘Amphibian passage’.
Animal Detection System (ADS)
Measure to alert drivers that a large animal is approaching the road. The system involves signs that emit flashing warnings, activated by large animal detection sensors. When an animal is detected, signs are activated warning drivers that animals may be on or near the road at that time.
Animal Vehicle Collision (AVC)
When an animal is hit by a moving vehicle. If the animal is a wildlife species also called ‘Wildlife Vehicle Collision’ (WVC). Synonym: Roadkill.
Anthropogenic
Generated and maintained, or at least strongly influenced by human activities.
Arboreal crossing structure
See ‘Tree top overpass’.
At Grade Passage
See 'Level crossing'.
Avoidance
Measures taken to anticipate and prevent adverse impacts on biodiversity before actions or decisions are taken that could lead to such impacts. See also: 'Mitigation Hierarchy'.
Avoidance measures
See 'Avoidance'. See also 'Mitigation'.