Peter Lougheed Wildlife Overpass

The Peter Lougheed Wildlife Overpass (PLWO) is a wildlife crossing infrastructure project spanning the Trans-Canada Highway (TCH) in Alberta. Led by DIALOG, the project is the first wildlife overpass in Alberta constructed outside of a national park. Designed to reduce wildlife-vehicle collisions (WVCs), the PLWO provides safe passage for wildlife and motorists along one of the busiest stretches of the TCH, reconnecting the landscape and rich ecology of Canada’s Bow River Valley.

The TCH east of Banff National Park in the Bow River Valley is one of the busiest roadways in Alberta. It serves as a key access point to the mountain parks of the Canadian Rockies, and connects numerous rural communities, including the Stoney Indian Reserve of the Stoney Nakado First Nation, with the City of Calgary. Over the last decade, the Bow Valley region has experienced exurban growth of residences and businesses, as well as an influx of tourism. Combined with the large number of goods and services that traverse the TCH, these factors create high traffic volumes, noise, light pollution, and other human-induced impacts on the surrounding environment.

The site hosting the PLWO is located within Kananaskis Country – a network of protected provincial parks in the Canadian Rockies. This section of the TCH intersects key wildlife migration routes of the Rocky Mountains for wildlife including both small and large species, such as ferrets, coyotes, deer, bears, elk, and bighorn sheep. The project was initiated due to these conditions, which have historically contributed to high rates of WVCs along this section of the highway. In 2018, DIALOG was engaged by the Alberta Transportation and Economic Corridors (TEC) to design the new overpass structure to mitigate the anthropogenic impacts caused by the highway and to reconnect the fragmented landscape for the safe passage of wildlife and people.

Read the Summary Link to Full Case Study

Understanding and Assessing Impacts

Statistics provided by the provincial government indicated that over 60 incidents of WVCs were reported along this stretch of the TCH each year. WVCs not only affect wildlife, causing serious injury or mortality, but people as well, costing almost $1 million in damage annually, physical injury, and psychological distress. Early estimates indicated that the construction of a wildlife overpass at this location could reduce collisions by approximately 80%. 

During early planning and design discussions, DIALOG’s approach to the crossing evolved from a human-centered problem to a wildlife-first solution. By fragmenting the landscape, the TCH acts as a physical barrier to the safe movement of wildlife, adversely affecting the ecosystem and its biodiversity. The aim of the project was to address the ecosystem fragmentation caused by the TCH and reduce WVCs by physically reconnecting the ecosystem and enabling safe animal movement throughout the corridor. While human safety and collision reduction were initial drivers, the project presented opportunities to support wildlife connectivity, migration, and genetic variability which eventually became the central focus. To achieve these goals, the project engaged a transdisciplinary design team of landscape architects and engineers, as well as ecologists and wildlife biologists. In this way, the project rethinks road infrastructure by prioritizing ecology rather than human use. 

Use of climate information in decision-making:

Climate information directly informed the plant species selection to ensure the vegetation was not only reflective of the surrounding ecosystem, but also adaptive to projected climate conditions. A selection of native and climate-adapted plant species were prioritized to support long-term resilience. Specific decisions in planting and grading were also made to mimic the natural terrain and replicate the surrounding forest ecosystem and expected changes under future climate conditions. Wildlife movement modeling and historic migration data were used to determine the location of the overpass. In addition to provincial standards and transportation regulations, statistics provided by the provincial government also informed design decisions. 

From an engineering perspective, the focus was less on climate projections and more on structural durability, longevity, and material performance over time. In consideration of the embodied carbon of the structure, intentional structural decisions were made to extend the lifespan of the overpass to avoid reconstruction. This was viewed as a key climate-resilient strategy. With attention paid to reinforcing materials and the use of high-quality concrete and steel to improve durability and cost efficiency, long-term visioning and foresight to achieve resilience were central to the project.

Identifying Actions

Design considerations during the conceptual planning and design phase centered on achieving a balance between technical complexity, driver safety and experience, and ecological and wildlife needs. The overpass was designed as a 60-metre wide structure, complemented by 6km of wildlife fencing on each side of the highway. Twenty-two ‘jump-outs’ were incorporated into the design of the fencing to address the potential for animals to end up on the highway side of the fence. 

The crossing also required a design responsive of the surrounding landscape, topography and local ecology. To achieve this, DIALOG established a naturalized planting palette appropriate for the local ecology. The palette enabled the seamless integration of the structure into the landscape. As the vegetation matures, it will become an extension of the immediate habitat over time. 

Actions to address ecological impacts began at the site-selection stage, where broader land-use patterns and long-term planning were considered to identify opportunities and constraints for wildlife movement. Design intentions aimed to improve ecological quality, such as noise mitigation and visual screening efforts, and the clustering of vegetation for wildlife respite opportunities. Design strategies to support genetic diversity included considerations not only for large mammals, but also smaller species, insects, and pollinators. 

Balancing structural constraints with ecological goals represented a notable challenge during the planning and design phase, particularly soil depth and loading on the arch structure. Soil depth varied across the structure depending on structural capacity, which directly influenced the planting design. The team at DIALOG worked to recreate a natural ecosystem on top of a highly engineered structure, requiring close collaboration between the landscape architects and engineers to align the soil profiles and plants, based on structural performance. 

Durability of the structure for water management was also a primary consideration. An extensive waterproofing system was designed beneath the soil layer on top of the structure, which allows water to support ecological function above the structure while also protecting the engineered components. Localized water management was a critical part of the design process, requiring close collaboration between engineering and landscape architecture disciplines.

The specific location of the PLWO will accommodate future widening of Highway 1. The existing lane arrangement at the overpass location consisted of a 4-lane divided highway (2 lanes in each direction). During the planning and design phase, several highway lane arrangements were considered as this would significantly impact the overall project cost. Each highway configuration needed to accommodate future widening of the highway to 6 or 8 lanes, thus requiring a larger, more expensive structure overall. The final design solution was for a 6-lane divided highway split into twin arches, each with 3 lanes and associated shoulders. This configuration was found to have the most reasonable balance between accommodating future highway widening and current project costs. 

Summary of design intentions:

  • Address habitat fragmentation – Improve ecological connectivity and support genetic diversity by supporting wildlife to safely cross the TCH along established migration routes 
  • Reduce WVC – Improve safety for both wildlife and motorists
  • Integrated ecosystem design – Create a functional habitat that supports wildlife movement and natural processes with a seamless integration/extension of the surrounding landscape
  • Durable, sustainable, and cost-effective infrastructure – Strategic use of materials and engineering strategies to ensure long-term performance, and optimize economic and environmental efficiency

Implementation

Construction of the PLWO began in April 2022 and was completed in the fall of 2024. In June 2025, the overpass was officially opened and named after the former premier Peter Lougheed, known for his role in conservation efforts and in the creation of Kananaskis Country. The $17.5 million overpass structure features twin corrugated steel plate arches, one spanning each direction of the highway.

To mitigate traffic impacts during construction, the wide arch design intentionally allowed for a shift of four lanes of traffic onto one side of the divided highway, using a temporary median crossover while the arch was being constructed over the closed lanes. Traffic was then directed through the first completed arch for the construction of the second arch.

The overpass arches sit on cast-in-place concrete footings, backfilled with gravel, and are covered with a substantial layer of clay and topsoil to allow naturalized vegetation to establish. Early evidence during construction showed rapid wildlife adoption, ultimately reflecting the effectiveness of the design and long-term research behind it. 

Outcomes and Monitoring Progress

The PLWO has set a precedent for future work in landscape connectivity practices and green infrastructure for the safe passage of humans and wildlife. Using trail cameras, ongoing monitoring focuses on wildlife use which represents a primary indicator of success, as well as a proxy for broader ecosystem health. Wildlife cameras continue to document and monitor wildlife use of the crossing, with early results showing a broader range of species than initially anticipated, including large mammals such as elk, bears, and cougars. 

By leading with interdisciplinary collaboration from the outset, this high level of professional integration throughout project development distinguishes the PLWO from earlier crossings. Unlike earlier wildlife crossings constructed in Alberta – all of which are built within national parks – the PLWO was delivered at the provincial level, through coordination between transportation, parks, and other government ministries, as well as front-end collaboration across disciplines including engineers, landscape architects, and wildlife biologists. Having diverse professional perspectives designing animal-first infrastructure was critical to the project’s success and represents one of the major lessons from the project. Successful ecological outcomes required careful attention to materials, soil quality, and construction coordination, enabling the landscape to establish and function ecologically over time.

Long-term responses to climate change and shifting migration patterns remain uncertain and will be observed on an ongoing basis. The PLWO is part of expanding efforts in Alberta to reduce WVCs and improve connectivity for wildlife in this vital corridor of the Bow River Valley region. Building this type of green infrastructure represents a fundamental shift and a substantial investment in climate resiliency. Since completion, the project has been commended via various news outlets and has received accolades including a 2025 Award of Excellence by the Canadian Consulting Engineers as well as a 2025 Environmental Achievements Award by the Transportation Association of Canada. 

Highlights of the landscape architect:

The landscape architects at DIALOG were equal collaborators from the beginning of project development, contributing to the planning and design of the overpass and playing a crucial role in the overall holistic design approach taken. In addition to developing technical construction drawings and delivering overall project documentation, the scope of the landscape architects included elements related to the consideration of unique landscape conditions, such as areas for wildlife rest, sightlines, noise mitigation and feeding, as well as soil depth coordination, planting design, habitat creation, and integration of site materials, in collaboration with the engineers and wildlife biologists.

The contributions of the landscape architect on the PLWO demonstrate how in infrastructure–landscape projects of this kind, the profession is well positioned to work across multiple scales and communicate across various disciplines. From site-specific design decisions to integrated corridor-scale planning within the larger ecological system of the Bow River Valley, designing wildlife infrastructure requires a broad skillset. As generalists, facilitators, and collaborators, landscape architects play a key role in translating design and ecological intent between disciplines, bridging technical design requirements with broader project narratives. For the PLWO, their role ensured that the overpass was situated within a connected ecological system rather than treating it as a standalone piece of civic infrastructure.

Next Steps

In June 2024, Alberta’s Ministry of Transportation and Economic Corridors announced several new wildlife crossing and fencing projects on Highway 3, as well as plans for three new crossings, including an overpass, on Highway 1A. Future wildlife infrastructure projects are being cited with reference to the PLWO to strengthen corridor connectivity, and are viewed as one component with a larger province-wide infrastructure strategy. The province also plans to retrofit several existing highway bridges and culverts for animals to use as crossings, and has launched the Wildlife Watch Program – a new driver safety initiative that aims to improve driver safety and protect wildlife by identifying collision-prone locations along the highway.

This project demonstrates how built infrastructure can repair ecological fragmentation and represents a shift toward building environments designed explicitly for nature and wildlife, with measurable benefits. The project shows that wildlife crossings are feasible, effective, and can produce net-positive environmental outcomes, all of which are directly beneficial to humans too. The PLWO illustrates how collaboration, commitment, and early disciplinary integration make projects at this scale achievable. 

Resources

 

This case study was prepared and authored by Sabrina Careri (Design Communications) on behalf of the CSLA. It forms part of the landADAPT Case Study Series, an educational resource and advocacy tool developed by the CSLA with the support of Natural Resources Canada’s Climate Change Adaptation Program.