Wildlife and Roads: Decision Guide Step 2.1.5

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2.1.1: Identify Species to Benefit from Potential Mitigation

2.1.2: Identify Ecological Processes (Water Flow, Animal Movement, Other)

2.1.3: Identify Landscape and Topographic Features That May Affect Movement and Mitigation

2.1.4: Identify Engineering and Maintenance Concerns

2.1.5: Weigh Cost Concerns with Potential Benefits

2.1.6: Identify Appropriate General Wildlife Crossing Type

2.1.7: Other Mitigation Options

2.1.8: References

2.1.5 Weigh Cost Concerns With Potential Benefits

The cost of wildlife crossings is probably the number one stated reason why some Departments of Transportation and Ministries of Transportation choose not to build them. For those unfamiliar with transportation project costs, a few statistics will put the cost of wildlife crossings into perspective. The Washington State Department of Transportation asked other states what the average costs were to build one mile of one lane of highway (a single-lane mile). In 2002, 25 state Departments of Transportation reported the cost averaged from $1 million to $8.5 million, with an average cost of $2.3 million (WSDOT 2002, White 2007). White (2007) reported that the American Road and Transportation Builders Association (ARTBA) stated that road construction projects put into place in 2006 totaled $105 billion. Within that context, wildlife crossings can cost from approximately $10,000 for a small culvert, to several million dollars for an overpass. In 1997, 2 wildlife overpasses were built over the Trans Canada Highway. The overpasses each cost $1,851,000 in Canadian dollars, or $1,350,799 U.S. dollars (http://www.mountainnature.com/Articles/CrossingStructures.htm). Consumer Price Index adjusted costs (1 Jan 1997-31 July 2007) would be ~$1,753,000, but may not account for the increased cost of some materials. Costs may be higher in different localities. Colorado is working to raise $4.5 million in federal funding to build an overpass in the vicinity of milepost 188 over I-70 west of Vail Colorado. An overpass was selected by advocates and consulting companies over an underpass in part because of 'engineering constraints, and the fact that a span bridge for wildlife to cross under the road would be cost prohibitive and would create unnecessary traffic delays' (Southern Rockies Ecosystem Project, url: http://www.restoretherockies.org/wildlife_bridge.html) . An estimate from engineers and planners can help weigh the cost of a box culvert versus a bridge, but financial costs are just part of the decision process. To illustrate an example of the struggle of weighing cost concerns, the Utah Department of Transportation is weighing the possibilities of installing an overpass, bridges, and box culverts to pass mule deer and elk across Interstate-70. If the least expensive box culvert is installed in a particular place, there is a much higher chance that the elk will refuse to use it than if it was a bridge underpass. Based on the results of the research project that led to this decision guide, in all of the United States, only 4 elk have ever been recorded in reports and papers, passing through a box culvert. That is after over 30 years of monitoring wildlife crossings and existing box culverts. If the less costly box culvert is chosen, additional considerations include the consequences of elk refusal to use it and possible attempts by elk to compromise the fence in order to cross the road. Certainly costs need to be considered with safety and ecological effectiveness in mind. Step 2.5 of the guide instructs on how to estimate cost effectiveness.


2.1.1: Identify Species to Benefit from Potential Mitigation

2.1.2: Identify Ecological Processes (Water Flow, Animal Movement, Other)

2.1.3: Identify Landscape and Topographic Features That May Affect Movement and Mitigation

2.1.4: Identify Engineering and Maintenance Concerns

2.1.5: Weigh Cost Concerns with Potential Benefits

2.1.6: Identify Appropriate General Wildlife Crossing Type

2.1.7: Other Mitigation Options

2.1.8: References