LESSONS LEARNED: TERRY FOX DRIVE WILDLIFE GUIDE SYSTEM INTENDED TO REDUCE ROAD KILLS AND AID THE CONSERVATION OF BLANDING'S TURTLE

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LESSONS LEARNED: TERRY FOX DRIVE WILDLIFE GUIDE SYSTEM INTENDED TO REDUCE ROAD KILLS AND AID THE CONSERVATION OF BLANDING'S TURTLE

Shawn R. Taylor, Nicholas Stow, Caleb Hasler, Kevin Robinson - 2014

Organization: Dillon Consulting Limited - Proceedings, Transportation Association of Canada

Location: Ottawa, Ontario, Canada

Abstract:

To mitigate the effects of a new roadway through sensitive forests and wetlands of the South March Highlands in Ottawa, a series of four wildlife-only culverts were installed along with another six hydraulic culverts carrying watercourses. Terry Fox Drive is a four lane arterial road that fragments wildlife habitat and created a physical barrier to existing wildlife movements between habitats.  Several species of mammals, reptiles and amphibians, along with a local population of Blanding’s turtle, an endangered species, was at risk of increased road mortality from traffic. The Wildlife Guide System (WGS) integrates  ten long box culverts (1.2 m X 1.8 m X ~50 m), three 0.60 m square catch‐basin ‘skylights’ in each, 907 m of 0.80 m high armour‐stone guide walls and 1.2 m high containment fencing throughout the 2.1 km  forested section. Guide walls and fencing included 40 cm overhangs slanted towards the habitat to avoid turtles from scaling the barrier.  Galvanized, welded wire fencing fabric with 50 mm X 100 mm openings was used on 75 mm diameter steel posts.  A level railway crossing remains the only gap in the WGS where animals can access the road. Camera traps were used over a three year study period, immediately following construction, to determine if local wildlife was using the WGS.  Road mortality was assessed on Terry Fox Drive and five other nearby roads.  Over the three‐year period, culverts were monitored for 42,799 hours and a total of 6,033 animals were observed representing 24 species.  Frogs, raccoons and rabbits were the most common users, but also fisher, porcupine, skunk, long‐tailed weasel, turtles and coyote were observed.  Ten Blanding’s turtles passed through the culverts, two in 2011 and eight in 2013.  Over the same period however, two Blanding’s turtles were killed by vehicles at the level railway crossing and two near unmaintained sections of the fencing.  Over all species, of the ~70 road kills reported, about 1/3 were on Terry Fox Drive near the level crossing.  The results suggest that the WGS, at a cost of $958K effectively mitigate road impacts on wildlife and is useful as a  mitigation tool for reducing impacts to slow‐moving animals like Blanding’s turtle.  We have learned that the armour stone walls degrade quickly (partly due to theft) and may be unsustainable in an urban setting.  Shorter, poured concrete walls would perform better, for longer periods, be safer, and the fencing would be easier to be tied in. The fencing design was good, but requires maintenance to ensure holes and damages are repaired.  Cutting grass behind the fence on slopes is problematic for the maintenance crew. The addition of skylights was an inexpensive addition that although untested, appears to be effective at reducing the ‘tunnel effect’ that effect animal movements.    

Tags:

Document Type: implementation results mitigation monitoring results
Project Type: fencing underpass
Infrastructure Asset: new roadway
Fauna: small mammals reptiles amphibians