The Idaho Transportation Department’s (ITD) U.S. 95/McArthur Lake project was designed to improve safety — but ended up changing history with new information about the area’s Native American heritage.
Meanwhile, ITD’s first wildlife overpass hopes to create a better future for mule deer, elk, and the motorists who travel State Highway 21 just east of Boise.
Because of their significant impacts, the two projects recently received awards from the American Association of State Highway and Transportation Officials (AASHTO). The McArthur Lake project earned the President’s Transportation Award for Equity, while the SH 21 project received the President’s Transportation Award for Environment and Planning.
For the $11 million U.S. 95/McArthur Lake project in Boundary County, construction was fairly straightforward — rebuild a one-mile, two-lane section of highway; add wider shoulders; and replace a box culvert with a 300-foot span bridge to provide safe animal passage under the highway.
The project’s biggest impact came when excavation unearthed important artifacts. McArthur Lake has been a traditional use area for the Kootenai Tribe of Idaho for generations, but the newly discovered cultural resources show the earliest human existence in the upper Columbia River Basin came 4,000 years earlier than previously thought.
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Discovery of the artifacts required an orchestrated approach to ensure their preservation. That involved partnering efforts between ITD, the Kootenai Tribe of Idaho, and contractors.
Jyl Wheaton-Abraham, a member of the Kootenai Tribe, served as lead archaeologist. With the support of ITD, she trained tribal members as cultural resource monitors. Their work led to the discovery of the resources that required a full archaeological excavation by Willamette Cultural Resources Associates of Oregon. Hundreds of tribal artifacts were collected, catalogued, and will be further evaluated.
Throughout the project, “Construction challenges were overcome in a unique way, primarily driven by strong communication and a mutual understanding and appreciation of the goals each party brought to the table,” said Carrie Ann Hewitt, ITD’s Project Manager. “Every day, Jyl and her team would communicate with the construction foremen to strategize about the next step, ensuring everyone would be able to work in the space they needed to accomplish their goals and allowing monitors to continue overseeing construction areas that had potential for additional archaeological significance.”
Extensive partnerships also allowed for completion of the 150-foot-long SH 21 wildlife overpass, with more than a mile of big-game fencing placed parallel to the highway to guide animals to the crossing. Wildlife began using the overpass within a month of its completion.
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In conjunction with the existing SH 21 wildlife underpass and fencing to the south, the project targeted an 80 percent reduction in collisions between vehicles and wildlife on the busy highway section, while ensuring safe habitat connectivity for the area’s mule deer and elk.
ITD wildlife-vehicle crash safety data and Department of Fish and Game GPS data determined the location of the overpass by finding where most migrating mule deer and elk crossed the highway.
During construction of the $7.5 million project, “One of the major challenges was phasing/staging construction in a very constrained SH 21 corridor limited by curves, topography, and drainage issues — and doing it in a safe and sound manner for those working and completing the construction of the wildlife overpass, while also permitting motorists and commercial traffic to travel through the project corridor with minimal disruption,” said Scott Rudel, ITD’s Project Manager.
To address that challenge, Contractor STG Pacific proposed a 25 mph, two-lane bypass that cut the project’s single-lane closures from 20 to six, removed the need for a traffic light signal system, and increased schedule surety. In addition, that allowed construction personnel to work behind barricades to increase their safety.
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The wildlife overpass was partially funded through the Federal Lands Access Program. To fund the remaining portion and develop the project, ITD received support from the Idaho Department of Fish and Game, U.S. Forest Service, U.S. Army Corps of Engineers, the City of Boise, Ada and Boise counties, numerous nongovernmental agencies, and the Western Federal Lands Highway Division of the Federal Highway Administration.
