Creative Bridge Design Reduces Wildlife-Vehicle Collisions by 85 Percent

Owner: Oregon Department of Transportation (ODOT Region 4)

Project Name: US 97-South Century Drive to USFS Boundary, Deschutes County, Oregon

Author: Scott Wallace - President and Principal Geologist with Wallace Group, Inc., based in Bend, Oregon

May 9, 2022

US 97 is the primary north-south transportation and freight corridor through central Oregon and parallels the eastern foothills of the Cascade Mountain Range.  Traffic volumes on US 97 have increased dramatically over the past decade with current volumes estimated at over 12,000 vehicles per day.  The US 97 corridor also marks a geographic transition from the forested volcanic Cascades to west, to the juniper, pine, and sage-covered High Lava Plains to the east.  This area also provides critical habitat for a variety of wildlife that like motorists, are always on the move.  Unfortunately, these paths cross and there are over 6,500 crashes involving wildlife reported in Oregon each year. 

Starting in 2012, ODOT initiated a series of projects to increase highway capacity to address the growing traffic volumes between Bend and Gilchrist in northern Klamath County.  However, highway widening significantly impacted wildlife movement including thousands of mule deer that migrate seasonally from the Cascades to the High Lava Plains, and back again.  To mitigate for vehicle-wildlife collisions, ODOT and the US Forest Service incorporated a suite of bridge underpasses and parallel highway fencing to funnel animals to the underpasses and provide safe passage for a variety of species including deer, elk, bobcat, badgers, and squirrels.  

The most-recent project improves safety and mobility along a three-mile segment between the South Century Drive (Sunriver) Interchange and Vandevert Road.  ODOT began work in 2020 to extend the four-lane divided highway, improve the Vandevert Road intersection, and construct wildlife migration structures.  When complete in summer 2022, the new segment will tie into 15 miles of widening, interchange, median barrier, and wildlife crossing improvements along US 97 in southern Deschutes County.  

Wallace Group provides geotechnical monitoring, inspection, and quality control testing during bridge/undercrossing construction for the Contractor (Carter & Company) to help document the US 97-South Century Drive project complies with ODOT plans, specifications, and safety objectives.  At Wallace Group, our engineers, earth scientists, special inspectors, and technicians are the recognized Geosystem experts working at the intersection of the natural and built environments.  We are gratified to be part of ODOT’s construction team that has helped reduce wildlife-vehicle collisions on this segment of US 97 by 85 percent since 2012.  

There are only five wildlife passage structures in Oregon, all along US 97.  While they provide a huge biological return on taxpayer investment, there is more to be done.  Other western states have had great success with wildlife passage infrastructure.  Colorado has 69 structures followed by California and Utah with 50, and Nevada with 23.  The Oregon legislature passed a recent bill allocating $7M in one-time funding to ODOT for wildlife corridor projects.  This funding should help make Oregon’s highways safer, but dedicated annual funding is needed to reduce Oregon’s wildlife passage gap with other western states.


A herd of mule deer use a US 97 bridge underpass to avoid highway traffic near Sunriver, Oregon.  
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