I-70 East Vail Pass Wildlife Crossings
A Priority Initiative of Summit County Safe Passages
Why Vail Pass?
Ecologically Significant
Nestled in the mountains between Copper Mountain and the top of Vail Pass, I-70 East Vail Pass has long been identified as an ecologically significant site both within and beyond Colorado for a variety of wildlife.
Encompassed by National Forest
Encompassed entirely by the White River National Forest, including the Eagles Nest Wilderness to the north, East Vail Pass is one the most intact and important habitats for many wildlife species along Colorado's mountain corridor.
Canada Lynx
East Vail Pass is home to one of the few known breeding populations of Canada lynx outside of southwest Colorado. Reintroduced to the state in the late 1990s, lynx are federally listed as a threatened species.
Vail Pass provides important summer and winter habitat for these beautiful native cats as well as their primary prey, snowshoe hare.
Rocky Mountain Elk
Vail Pass also provides important summer habitat for another of Colorado's iconic species, Rocky Mountain elk.
Reconnecting landscapes that are otherwise intact, like Vail Pass, is key to ensuring these majestic animals have access to the resources they need to survive.
Mule Deer
Vail Pass is also important summer habitat for mule deer. Both mule deer and elk present a significant hazard to drivers on I-70 so providing safe passage for them will also improve safety for the traveling public.
Summit County Safe Passages Plan
The Summit County Safe Passages Plan, which identifies areas with the greatest need for wildlife to move safely across highways within Summit County, was completed in 2017 and identifies East Vail Pass as a priority initiative.
Current Conditions
Divided Highway
I-70 on East Vail Pass is a divided highway with a wide, natural, open median. West Tenmile Creek and the Vail Pass Recreation Trail wind down the middle of the median.
Important Travel Corridor
An important travel corridor for Colorado’s adventure community, residents, tourists and industries, this stretch of I-70 sees, on average, 23,000 vehicles a day.
This much traffic presents a significant barrier and many animals no longer attempt to cross. Those that do are often unsuccessful.
Traffic Volume
Research from Wyoming shows that mule deer need a break in traffic of at least 60 seconds to be able to cross a roadway safely (Riginos et al. 2018).
This 60-second video of traffic on East Vail Pass was taken midday on a fall weekday, and shows that gaps in traffic along this stretch of I-70 are rare, even outside of peak travel times.
Existing Span Bridges
Five large span bridges exist on the eastbound lanes of I-70 on East Vail Pass. However, only one is present on the westbound lanes along this five-mile stretch of highway.
No direct connections exist between these bridges to allow for safe wildlife passage across the entire highway.
Existing Structures on East Vail Pass
I-70 on East Vail Pass currently has five large span bridges on the eastbound lanes, but only one on the westbound lanes. Click through the images below to learn more about these existing structures and see how adding the three proposed structures will reconnect East Vail Pass by creating a full system of safe crossing opportunities for wildlife.
Wilder Gulch
Smith Gulch
Stafford Gulch
Guller Creek
West Tenmile Creek
Corral Creek
Proposed Overpass
Proposed Underpass
Proposed Underpass
Wilder Gulch
Heading east from the top of Vail Pass, the Wilder Gulch span bridge underpass is the first existing structure on the eastbound lanes at MP 191.0.
Smith Gulch
The next existing span bridge underpass structure on the eastbound lanes is at Smith Gulch at MP 192.0.
Stafford Gulch
The third existing span bridge underpass structure crosses over Stafford Creek at eastbound MP 192.5.
Guller Creek
The fourth existing span bridge underpass structure is over Guller Creek at eastbound MP 193.5.
West Tenmile Creek
The fifth and final existing span bridge underpass structure on the eastbound lanes is at MP 194.0 over West Tenmile Creek and the Vail Pass Recreation Trail.
Corral Creek
The only existing span bridge underpass structure on the westbound lanes crosses over Corral Creek near the top of Vail Pass at MP 191.5.
Proposed Overpass
Proposed hourglass overpass structure on the westbound lanes at MP 192.3.
Proposed Underpass
Proposed arch underpass structure on the westbound lanes at MP 193.0.
Proposed Underpass
Proposed buried bridge underpass structure on the westbound lanes at MP 193.5.
Feasibility Study
The Summit County Safe Passages Plan recommends three wildlife crossing structures - two underpasses and one overpass - for the westbound lanes of I-70 on East Vail Pass. With funding from Vail Resorts, Arapahoe Basin, and the Center for Large Landscapes, the Wood Engineering team completed the I-70 East Vail Pass Wildlife Crossings Feasibility Study in late 2020. This study developed and evaluated preliminary engineering designs for the three recommended locations.
Wildlife Needs and Feasibility
The I-70 East Vail Pass Wildlife Crossings Feasibility Study considered wildlife needs and the feasibility of each crossing relative to cost, traffic, environmental conditions, topography and constructability at each crossing location.
Wildlife Exclusion Fencing
Wildlife mitigation must be accompanied by wildlife exclusion fencing to ensure success of the project. On East Vail Pass, the eastbound and westbound lanes of I-70 must each be fenced so that the habitat in the wide, open median remains useable for wildlife.
Buried Bridge Underpass
Proposed Structure MP 193.5
The Summit County Safe Passages Plan recommends an underpass structure at MP 193.5
A diversity of structure types (both underpasses and overpasses) were evaluated on East Vail Pass to ensure suitable crossing opportunities for the greatest variety of species.
Three underpass options were considered in the feasibility study - a buried arch, a traditional bridge, and a buried bridge.
The study recommends a buried bridge at MP 193.5
Important for Elk
This location is important for elk and is across from an existing bridge under the eastbound lanes, creating a nearly direct connection across I-70.
By providing a larger underpass at MP 193.5 and an overpass at MP 192.3, elk passage is accommodated across the widest geographic area.
Underpass Height
Underpass openings must be high enough to accommodate large animals like elk and moose.
Preliminary design of the buried bridge assumes a standard precast concrete girder bridge with a 15 foot clearance below.
Underpass Width
Underpass openings must also be wide enough to encourage animals to enter.
Preliminary design assumes an 85 foot opening that will retain connectivity for target species if a third lane is added in the future.
Underpass Length
The overall length of the proposed underpass structure from outside edge to outside edge would be 45 feet.
Underpass Fill
A buried bridge is essentially a traditional bridge with four feet of fill on top of the bridge deck. This provides insulation to avoid the icing concerns of a traditional bridge.
Before and After - Buried Bridge Underpass
Use the slider to see what the proposed buried bridge underpass location looks like now and what it will look like once the structure is built.
Before and after at the proposed buried bridge underpass location
Arch Underpass
Proposed Structure MP 193.0
The Summit County Safe Passages Plan recommends an underpass structure at MP 193.0
A diversity of structure types (both underpasses and overpasses) were evaluated on East Vail Pass to ensure suitable crossing opportunities for the greatest variety of species.
Three underpass options were considered in the feasibility study - a buried arch, a traditional bridge, and a buried bridge.
The study recommends a buried arch underpass at MP 193.0
Although smaller than the other underpass options, the proposed arch underpass was designed with adequate vertical clearance and opening size to accommodate mule deer, lynx and possibly elk once they habituate to the structure.
Underpass Height
Preliminary design of the buried arch underpass assumes a precast concrete arch with a 13.5 foot clearance below.
Underpass Width
Preliminary design assumes a 44 foot opening that will retain connectivity for target species if a third lane is added in the future.
Underpass Length
The overall length of the proposed underpass structure from outside edge to outside edge would be 45 feet.
Underpass Fill
Four feet of fill on top of the bridge deck would provide insulation to avoid the icing concerns of a traditional bridge.
Before and After - Arch Underpass
Use the slider to see what the proposed arch underpass location looks like now and what it will look like once the structure is built.
Before and after at the proposed arch underpass location
Hourglass Overpass
Proposed Structure MP 192.3
The Summit County Safe Passages Plan recommends an overpass structure at MP 192.3
A diversity of structure types (both underpasses and overpasses) were evaluated on East Vail Pass to ensure suitable crossing opportunities for the greatest variety of species.
Two overpass options were considered in the feasibility study - a traditional angled wall overpass and an hourglass overpass.
The study recommends an hourglass overpass at MP 192.3
Important for Elk
Although more expensive than an underpass, an overpass would provide better connectivity for a wider variety of species, especially elk which require excellent visibility and openness to feel comfortable using a structure.
By providing an overpass at MP 192.3 and a larger underpass at MP 193.5, elk passage is accommodated across the widest geographic area.
This would be the first hourglass-shaped wildlife overpass in the U.S.
This design offers a unique aesthetic appeal, innovative engineering, and the visibility of an overpass provides an excellent public education opportunity.
Overpass Width
An appropriate overpass width was calculated based on the distance wildlife must travel to get across the structure.
Overpass Width
Despite a narrower width at the center point, the hourglass overpass is the same width as a traditional overpass in the approaches to the crossing structure. This narrower width potentially brings down the cost of the structure.
Overpass Slope
The hourglass design also has a more gentle and even grade across the length of the structure, providing better visibility for wildlife crossing over the structure.
Overpass Roadway Opening
The preliminary design provides an 80-foot opening for I-70. This accommodates three 12-foot lanes, a 4-foot inside shoulder, and a 10-foot outside shoulder with a buffer to account for snow storage.
Before and After - Hourglass Overpass
Use the slider to see what the proposed overpass location looks like now and what it would look like once the structure is built.
Before and after at the proposed overpass location
Special Considerations
The feasibility study included a preliminary engineering and environmental review to identify potential factors that could affect the design or construction of the wildlife crossings. Each location has special considerations that will require continued review as the project moves onto the next phase of project design and National Environmental Policy Act (NEPA) clearance.
These considerations include snow storage, wetlands, traffic detours, and accommodating a potential future third lane. Additional considerations are necessary for the overpass structure including shading, noise and light attenuation and blowing snow.
Snow Storage
The feasibility study evaluated providing a wider shoulder to offset the potential effects of CDOT’s snow plowing operations at both underpass locations. Plowing could create pileups on the ground below the roadway, partially blocking the entrance to the structure. However, as much as 60 feet of additional roadway would be needed to provide adequate snow storage and this would be detrimental to wildlife usage. Larger animals have generally migrated out of the area during winter, and medium and small bodied species that inhabit the area year round would have adequate clearance even with the expected snow pileup.
Wetlands
As the project moves onto the next phase of project design and NEPA clearance, each location will be analyzed for potential wetland impacts. Preliminary investigation identified multiple wetland areas in the project area, including what is likely a fen. Fens can take thousands of years to form and are a high priority for conservation and restoration. The next phase of project design and environmental clearance will ensure impacts to the wetlands and other riparian areas are avoided or minimized to the greatest extent possible through design and location adjustments.
Traffic Detours
In accordance with CDOT’s lane closure policies for I-70 in this location, no long-term closures will be allowed and two lanes of traffic must be maintained during construction. The underpass structures would be constructed with a traffic detour to maintain the necessary traffic lanes. Temporary detours would not be required for the proposed wildlife overpass as the majority of the construction would be completed outside of the traveled way. Night closures would be required to perform any overhead, safety-critical work.
Third Lane Accommodation
I-70 on East Vail Pass is currently two lanes in both directions, but the feasibility study took into consideration that the proposed structures cannot preclude the potential construction of a third lane. The proposed overpass concept provides a wide enough opening for the roadway to accommodate a third lane. Likewise, the proposed underpass concepts are wide enough that connectivity won't be impacted by the extra distance wildlife will have to travel through the structure if a third lane is added.
Shading
Shading refers to the overpass blocking the sun, which impacts snow and ice melt. A shading investigation was conducted to determine the typical number of hours of shading at various locations on the roadway adjacent to the structure. As seen in this image, areas that are completely shaded throughout the day (dark blue) are outside of the traveled way or directly under the structure. Additional study will determine if the shading creates a safety issue requiring mitigation.
Noise and Light Attenuation
Soil berms have traditionally been used along either side of an overpass to block wildlife from the light and noise impacts of the traffic passing below. However, soil berms create a large footprint on an overpass, necessitating a wider structure, and add deadload to the structure. Noise walls provide the same function as soil berms with no added footprint.
Blowing Snow
Strong winds and blowing snow may cause cornices to form at the edge of the overpass and drop snow onto I-70. To dissipate blowing snow and reduce the likelihood of cornice formation, the feasibility study developed a hybrid noise and permeable wall solution consisting of a 4-foot-high solid wall topped by a 4-foot-high permeable fence.
Wildlife of East Vail Pass
Wildlife monitoring is an essential step in assessing how effective wildlife crossing structures are in restoring wildlife movement corridors. Community scientists have been helping to monitor wildlife along East Vail Pass since 2015 through the Colorado Corridors Project, an initiative of Rocky Mountain Wild and Denver Zoo. Nearly every species of wildlife found in Colorado’s mountains has been documented using habitat along I-70 East Vail Pass.
Points do not depict exact locations.
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Next Steps
Now that the The I-70 East Vail Pass Wildlife Crossings Feasibility Study is complete, next steps include conducting environmental review processes, completing final engineering designs, and constructing the mitigation infrastructure.
Project Scoping and Final Design
The next phase will begin with project scoping to ensure that the proposed designs do not negatively impact the environment. Once this has been established, the designs can be refined and approved, at which point they will be ready for bidding and construction.
Construction
Once final design drawings are completed, the project can be advertised for bidding. Construction will include monitoring to ensure environmental compliance with stakeholder and permit requirements. Construction will also be scheduled to minimize traffic interruptions and detours as I-70 is an important transportation corridor through the Rocky Mountains.
Fundraising
While wildlife crossings provide important ecological and economic benefits, all of these steps will require nearly $21 million to complete. Support can come from a variety of private, public, state and federal sources.
What Can You Do?
Donate Now
Funds are needed to complete the design and construction of these wildlife crossings on East Vail Pass.
Every dollar helps!
Spread the Word
Talk with your friends about the impact that I-70 traffic has on wildlife and the importance of reconnecting wildlife habitat.
Become a Community Scientist
Community scientists help monitor wildlife along East Vail Pass using remote triggered cameras. This helps to understand what species are impacted by traffic along I-70.
Participate in an Event
Summit County Safe Passages host events throughout the year to raise awareness and funds for wildlife crossing projects. Show your support by volunteering, attending or sponsoring an event.
