In western Weber and Davis Counties, just north of Salt Lake City, the Utah Department of Transportation expects a 74% increase in residents by 2050. With a strong demand for new housing, commercial development and active transportation, a substantial improvement to mobility was needed in the area to keep up with expected growth.

That improvement came this past January as communities along the corridor came together to celebrate the opening of the West Davis Highway, a transformative project that will reshape how the region moves for decades to come.

Shared vision for mobility

The West Davis Highway is part of UDOT’s long-range vision to improve mobility and enhance quality of life in northern Utah. It provides key connections to I-15 and Legacy Parkway (SR-67) north of Salt Lake City. UDOT utilized a best value, design-build delivery method to accelerate the project schedule by two years.

HNTB served as the project’s lead design consultant — along with more than 10 design partners — to Farmington Bay Constructors (FBC), a joint venture made up of Ames Construction, Wadsworth Brothers Construction and Staker Parson Materials & Construction. This design-build team worked together to deliver on UDOT’s goals of improving regional mobility, enhancing peak-period mobility, increasing interconnection between transportation modes, supporting local growth objectives and providing more pedestrian and bicycle options.

The highway project is a complex 16-mile segment involved a freeway-to-freeway interchange and several service interchanges, multiple grade separations, 40 structures and a greenfield alignment through soft soils with a high-water table. It also included Utah’s longest span bridge with integral bents.

“FBC, along with HNTB as our design partner, was committed to a team environment and project success,” said Robert Patcheck, FBC project manager, Ames Construction. “The collaborative process we established generated numerous innovative ideas. HNTB brought knowledgeable design build engineers that understood construction methods and the importance of schedule.”

To enhance communication and efficiency, the contractor and design project team co-located in a workspace, with UDOT’s project team.

Innovation in a context-sensitive design

Drawing on expertise in offices across the country, the design-build team developed a context-sensitive design and met almost daily with UDOT through the design stage to advance ideas around design geometry, materials, constructability and maintenance. Together, the agency and the project team assessed how the project design would meet the goals of maximizing design and construction quality and minimizing stakeholder and environmental impacts. Additionally, the future needs of West Davis Highway were taken into account by reducing the long-term costs for maintaining the infrastructure.

Reviewing the bridges and crossings along the alignment, the team identified the I-15/Legacy Parkway southeast interchange and the nearby 650 West overpass as key areas for innovation.

UDOT’s preliminary southeast interchange design staggered the northbound and southbound ramps, spreading them out over a mile. The revised design co-located the ramps, making them more compact. The reconfiguration proved less costly to construct, reduced construction time and minimized wetland impacts.

Another innovation was a change to the initial crossing design of West Davis Highway and 650 West. Instead of having West Davis Highway cross over 650 West, it goes under it.

“However, there were buried petroleum and high-pressure gas lines in this area,” said Yvette Abdelmalek, HNTB design manager. “The lines had minimal tolerance to settlement, and the more soil placed on them, the more they would have deflected. We needed to achieve zero inches of deflection of those lines. By reversing the configuration — taking 650 West up and over West Davis Highway — we reduced the amount of fill needed and eliminated settlement risk.”

Early investment pays off

The area’s geotechnical conditions also offered opportunities for innovation. Soils along the alignment are extremely soft. A year before UDOT awarded the project contract, the contractor team invested in the construction of a test fill. Monitoring the huge dirt stockpile over 12 months allowed the team to determine how much the existing soils would settle or rebound.

“The test fill gave us a year of site-specific data over and above what UDOT provided and gave us certainty about what to expect as the project progressed,” Abdelmalek said. “That investment by our contractor team shortened the schedule by a year, informed our design and helped us significantly reduce geotechnical risk.”

Based on testing site results, the team was able to accurately predict the resulting settlement and plan the work more efficiently. They also elected to use lightweight geofoam fill, which reduced the weight placed on the soft soils, minimizing settlement adjacent to I-15 and UPRR railroad tracks.

Protecting the Great Salt Lake ecosystem

The highway lies adjacent to two environmentally sensitive areas: the 4,400-acre Great Salt Lake Shorelands Preserve managed by The Nature Conservancy and Farmington Bay, a 18,000-acre, state-managed waterfowl management area. A combined 800 acres of wetland and upland habitat was added to these two areas for environmental mitigation.

UDOT worked closely with The Nature Conservancy and the Utah Division of Wildlife Resources to mitigate the new highway impacts to the wetlands and its wildlife. Because of the area’s environmental sensitivity, UDOT’s technical criteria required a quiet pavement and dark sky lighting, and communicated a preference for a lower-profile roadway that would limit visual and noise impacts.

The design-build team met these criteria and found additional ways to enhance the environment by expanding the size of a waterfowl pond and replacing high-maintenance irrigation ditch systems with pressure irrigation systems.

Stakeholder engagement and community impact

To continue to support and capitalize on the strong stakeholder relationships UDOT had built throughout the environmental process, the agency and the design-build team established a resident working group (RWG) that met regularly during design and construction.

The RWG included representatives of local area governments, businesses, residents, emergency services and other stakeholders. RWG members acted as liaisons for their neighborhoods, and the meetings allowed the project team to share updates, gather feedback and respond to member questions.

Also important to UDOT was the creation of a trail system that parallels the length of West Davis Highway. The finished project includes 14.5 miles of new trails and two horse crossings that improve user experience for the area’s active trail community, including cyclists, pedestrians and equestrians.

The project’s trail design:

• Eliminated 3,160 feet of out-of-direction travel for Legacy Parkway Trail users.
• Reduced the length of steep grades on Buffalo Ranch Trail.
• Used an equestrian trail pavement section that creates a safer and more horse-friendly surface with greater traction for equestrian users along Buffalo Ranch and Great Salt Lake Shoreline Trails.
• Connected the West Davis Trail to the Emigrant Trail, Rail Trail and Legacy Parkway Trail to create an expansive, connected trail system.
• Where the trails run within 50 feet of the highway, crash-rated barriers were installed to ensure safety for trail users.

Delivering a transformative corridor

Opened January 6, 2024, the West Davis Highway improves regional mobility for the area’s growing population while minimizing impacts to the environment and the communities it serves. Six new interchanges connect the new highway to I-15, Legacy Parkway, and key state and local roads to increase travel capacity in Davis County.

The opening took place nine months ahead of schedule, the result of what UDOT Executive Director Carlos Braceras called, “a concerted effort to open up this new highway as soon as possible because we know it will immediately make a huge difference in people’s lives.”

“Behind the project’s success was a shared vision by the design-build team to deliver on UDOT’s goals,” said Juan Uribe, HNTB project executive. “The collaboration among the team, with the client and with the communities enabled us to achieve best value — a blend of innovations, construction speed, cost effectiveness and an accelerated schedule.”

Plans are already underway for a second phase that will extend the West Davis Highway northward, supporting the next stage of growth in the area and ensuring achievement of UDOT’s vision to “Keep Utah Moving.”