By Suze Parker, Contributing Author
By 2050, a 74% increase in residents is predicted in western Weber and Davis Counties just north of Salt Lake City.
The area’s explosive population growth has driven not only a strong demand for new housing and commercial development, but also for substantially expanded transportation infrastructure that can accommodate this increase in people.
The Utah Department of Transportation (UDOT) delivered on that improvement need this past January as area communities came together to celebrate the opening of the West Davis Highway, a transformative corridor that will reshape how the region moves for decades to come.
A 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 Interstate 15 and Legacy Parkway (State Route-67) north of Salt Lake City.
In response to the area’s escalating transportation needs, UDOT utilized a best value, design-build delivery method, which accelerated 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 and Construction.
This design-build team worked collaboratively 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.
To enhance communication and efficiency, FBC and the design project team colocated in a workspace with UDOT’s project team.
“FBC, along with HNTB as our design partner, was committed to a team environment and project success,” said Robert Patcheck, FBC project manager at Ames Construction. “The collaborative process we established generated numerous innovative ideas.”
Innovation in a Context-Sensitive Design
The West Davis Highway project is a complex, 16-mile segment that 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.
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. The team also considered the West Davis Highway’s future needs 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 State Route 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 colocated 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.
“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 — the design team reduced the amount of fill needed and eliminated settlement risk.
Early Investment Shapes Geotechnical Response
The area’s geotechnical conditions also offered opportunities for innovation. Soils along the alignment are extremely soft.
To reduce risk to schedule, the team created a geotechnical testing site a year before UDOT awarded the project contract. They built a 40-foot-high test fill near the I-15/Legacy Parkway southeast interchange.
Over 12 months, the team monitored the huge dirt stockpile to determine how much the existing soil 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 shaved a year off the schedule, 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 Union Pacific Railroad tracks.
Protecting the Great Salt Lake Ecosystem
The West Davis 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, an 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, The Nature Conservancy and the Utah Division of Wildlife Resources worked closely together to mitigate the new highway’s impacts to the wetlands and its wildlife.
Because of the area’s environmental sensitivity, UDOT’s technical criteria for West Davis Highway required a quiet pavement and dark sky lighting, in addition to communicating a preference for a lower-profile roadway that would limit visual and noise impacts.
The design-build team not only met these criteria, but also 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.
An Expanded System for an Active Trail Community
To continue supporting and capitalizing 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 served as liaisons for their neighborhoods, and the meetings allowed the project team to share updates, gather feedback and respond to member questions.
UDOT also prioritized 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.
A Corridor that Reshapes the Region
The West Davis Highway improves regional mobility for the area’s growing population and meets future transportation needs while minimizing impacts to the natural environment.
Six new interchanges connect the new highway to I-15, Legacy Parkway and key state and local roads to increase travel capacity in Davis and western Weber Counties.
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, 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.” RB
Suze Parker is a public relations consultant and writer who frequently writes about roads, bridges and other infrastructure projects.
