Monday, December 26, 2011

Engineering Animal Overpasses and Underpasses




Driving through Banff last summer, I had a chance to see the overpasses built in the park.  They were somewhat over engineered but certainly did the job.  What these numbers make obvious is that the animals soon learn of the overpass or for that matter the various forms of underpass and the related game trails are quickly adjusted to take full advantage of them.


Raccoons really do not talk to foxes, but have no difficulty on following another’s passage.  Camera work has long since shown that game trails are busy places indeed so long as no humans are about.

Certainly underpasses and good fencing is an economic method to control animals from attempting to cross highways.

On the other hand we are not far away from been able to fully sensorize a right of way and link the information back to oncoming traffic to practice simple evasion.  We certainly need to do that in Newfoundland were car - moose events are now endemic.



The safe way for animals to cross the road…


Underpasses seem to work

December 2011: Design features such as overpasses keep drivers moving safely on our highways, letting cars pass in different directions without interacting with other cars or trains. Allowing wildlife to move from one side of the road to the other without encountering vehicle traffic is a challenge for transportation planners and wildlife managers. As transportation networks continue to expand, a similar solution may help avoid wildlife-vehicle collisions.
A new study rates the effectiveness of highway underpasses for wildlife. Researchers found that the cost of building these underpasses in the highway proved to be a savings of property and life.
Bringing together black bears and cars...

Collisions between wildlife and vehicles can cause substantial damage to vehicles and injure – or even kill – people. Wildlife doesn't fare much better. High mortality due to vehicles can affect the viability of some small populations of animals.

A new route planned for U.S. Highway 64 in Washington County, North Carolina, gave researchers the opportunity to document wildlife activity both before and after the road was built. The new route cut through a forested and agricultural area, bringing together cars and resident animals such as black bears, red wolves, and white-tailed deer.

Part of the highway construction included three underpasses with fencing running alongside the roadways near each underpass to ‘funnel' the animals through.

With the use of multiple cameras and surveys of animal tracks, researchers counted wildlife activity both in the planning and construction stages of the highway and after it was completed and open to traffic. Before road construction, the cameras captured 242 instances of deer passing through the area where the underpasses would be.
New 'funnel' saw 60 per cent reduction in animal deaths

During a 13-month period after construction, 2,433 photographs of various animals, primarily deer, but also bears, raccoons, and domestic dogs and cats, were taken as they used the underpasses. Animal deaths from vehicle collisions were counted as well.

When compared with reports from adjacent sections of U.S. Highway 64, the new section of road experienced a 58 per cent reduction in wildlife mortality.
Improvements to further reduce wildlife-vehicle collisions include continuous fencing along roads rather than small sections, higher fences, and fences dug into the ground to prevent smaller animals from going underneath. Drainage culverts placed at more frequent intervals, rather than larger underpasses built farther apart, could provide a more economical way to allow animals to pass under the road.

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