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Providing evidence to improve practice

Individual study: Overcoming the barrier effect of roads –how effective are mitigation strategies? An international review of the use and effectiveness of underpasses and overpasses designed to increase the permeability of roads for wildlife

Published source details

van der Ree R., van der Grift E., Mata C. & Suàrez F. (2007) Overcoming the barrier effect of roads –how effective are mitigation strategies? An international review of the use and effectiveness of underpasses and overpasses designed to increase the permeability of roads for wildlife. Proceedings of the 2007 International Conference on Ecology and Transportation, Center for Transportation and the Environment, North Carolina State University, Raleigh NC, USA, 423-431.


This study is summarised as evidence for the intervention(s) shown on the right. The icon shows which synopsis it is relevant to.

Install overpasses over roads/railways Terrestrial Mammal Conservation

A global review in 2007 of 123 studies investigating the use of wildlife crossings (van der Ree et al. 2007) found that all studies reported that the majority of underpasses and overpasses were used by wildlife. A total of 1,864 structures were reported on, mainly underpasses (83%; including culverts (742 examples), bridges (130), tunnels (340) and unknown types (333)). Overpasses included land bridges (68), overpasses with small roads (112), canopy bridges (8), glider poles (1) and others (35). Structures provided crossings over or under roads (113 studies), railways (5 studies), both (1 study), canals (2 studies) and a pipeline (1 study). Studies were from Europe (55 studies), the USA (30 studies), Canada (nine studies), South America (one study) and Australia (29 studies).

(Summarised by Rebecca K. Smith)

Install tunnels/culverts/underpass under roads Terrestrial Mammal Conservation

A global review in 2007 of 123 studies investigating the use of 1,864 wildlife crossings (van der Ree 2007) found that all studies reported that the majority of underpasses and overpasses were used by wildlife. Of the 1,864 structures reported on, most were underpasses (83%), including culverts (742 examples), bridges (130), tunnels (340) and unknown types (333). Structures provided crossings over or under roads (113 studies), railways (5 studies), both (1 study), canals (2 studies) and a pipeline (1 study). Studies were from Europe (55 studies), the USA (30 studies), Canada (nine studies), South America (one study) and Australia (29 studies).

(Summarised by Rebecca K. Smith)