Wildlife Underpasses Effectiveness Specifications Surrounding Terrain Implementation Cost Maintenance

Effectiveness 87 percent (average) when used in combination with large-mammal fencing

Specifications. Dimensions of the three different types of crossing structures. 4 Crossing Structure TypeDimensions (as seen by the animals) Large-mammal underpass7.6–8.7 yd wide, 4.4–5.5 yd high Medium-mammal underpass 2.6–9.8 ft wide, 1.6–8.2 ft high Small- or medium-mammal pipe 1.0–2.0 ft in diameter

Open-span bridge Large-mammal underpass Medium- mammal underpass Small- to medium- mammal pipe Ungulates Deer sp.  Elk  Moose    Mountain goat    Bighorn sheep    Pronghorn  

Open-span bridge Large-mammal underpass Medium- mammal underpass Small- to medium- mammal pipe 4 Weasel    Pine marten   Fisher    Striped skunk  Badger  ?? Wolverine  ??  Bobcat  Canada lynx  ??  Cougar  Fox1  Fox2   ?? Coyote  Wolf    Black bear  Grizzly bear   

Surrounding Terrain Roadway is relatively higher than the surrounding terrain The roadbed does not have to be :  raised  the approaches lowered  reduces the overall excavation

It is advisable: To allow animals to see to the other side Avoid flooding of underpasses and the associated soil erosion

Wildlife fencing alongside the road corridor typically ties into the wing walls of the underpass or the structure itself ( above for smaller culverts) Noise and light disturbance from the road need to be minimized (e.g., employing sound-attenuating walls above the entrances).

Impementation

At-Grade Animal “Sidewalks”

Costs TypeSizeCost Open-span Bridge (Hwy 93) 32.8 yd in w and 13.1 yd in length $423,483 in 2006 Open –span Bridge (Baniff)* 13.1 yd in w and about 5.5 yd in height $700,000–1 million (1995–1997) Can Open span Bridge (Baniff )* to 27.3 yd-wide$2.5 million (2007) Can Large Mammal Underpass (Canada) 7.7 yd) in w and 4.4 yd in height ( across a 4 lane road $225,000 - $250,000 ( ) Can Large Mammal Underpass (Netherlands) 7.7–10.9 yd wide and about 4.4 yd high and 21.9 yard wide €600,000–€1,000,000. Large Mammal Underpass (Montana) arched culverts (3) 7.7–8.7 yd in w and 5.5 yd in height (road width) varies between 20–24 yd $217,000 in 2006 each ( for 3)

Costs Medium Mammal Underpass box or elliptical culvert 9.8–13.1 ft) wide and high $180,000 (1995– 1997) CAN Medium Mammal Underpass box culverts (Montana) 3.9–5.9 ft wide and high and 30.1 yd long 6.6 ft wide, 4.9 ft high and 30.1 yd long $69,000 each in 2006 Medium Mammal Underpass box culverts (Netherlands) 2.6–4.3 ft wide, 1.6– 2.5 ft high and a road width of 21.9 yd €24,000-50,000. Small and Medium Pipes 2.0 ft in diameter/ 21.9 yds long €14,000–€24,000 (2005)

Maintenance