Table 1. Mean overpass parameters measured in Google Earth Pro 7.3.4.8573 (64-bit), associated expert recommendations, and compliance rate of (a) Global, (b) North American and (c) European structures.
| Wildlife overpass parameters (m) | Expert recommendations3,4 (m) | Compliance rate (%) | |
|---|---|---|---|
| a: Global | |||
| Mean width (n = 97)1 | 34 (3–76) | - | - |
| Mean length (n = 90)2 | 65 (21–138) | - | - |
| Mean width: length ratio (n = 90) | 0.58 (0.06–2.76)* | - | - |
| b: North America | |||
| Mean width (n = 28)1 | 33 (6–65) | >50 | 29 |
| Mean length (n = 27)2 | 62 (29–109) | - | - |
| Mean width: length ratio (n = 27) | 0.53 (0.09–1.10)* | - | - |
| c: Europe | |||
| Mean width (n = 52)1 | 38 (11–76) | >40 | 50 |
| Mean length (n = 52)2 | 72 (23–138) | - | - |
| Mean width: length ratio (n = 52) | 0.60 (0.13–2.76)* | >0.8* | 21 |
Notes:
1
Estimated inner width of overpass using ruler tool in Google Earth Pro 7.3.4.8573 (64-bit).
2
Estimated headwall length of overpass structures using ruler tool in Google Earth Pro 7.3.4.8573 (64-bit).
3
Expert width recommendation of 50 m or greater for overpasses in North American (Clevenger & Huijser, 2011), similar recommendations in Iuell et al. (2003).
4
Expert width: length recommendations of 0.8 or greater for overpasses in Europe (Iuell et al., 2003).
*
Unitless ratio.