Client expectations
Best in State:
Gold Award


Project: Granite Falls alternate route
Client: Snohomish County

Photo courtesy of WHPacific
A new road through Granite Falls was designed with three roundabouts to help reduce stop-and-go truck traffic.

The Mountain Loop Highway begins in Granite Falls, about 17 miles northeast of Everett in Snohomish County.

For years, increasing traffic in downtown Granite Falls — especially trucks heading to and from nearby quarries — has caused noise, dust and congestion, and heightened concerns for safety and the local quality of life. During the busiest periods, a truck drives through downtown an average of every 30 seconds.

Snohomish County’s solution was to build the Granite Falls alternate route, a new principal arterial that would connect the Mountain Loop Highway on the east side of town with state Route 92 on the west side. Though a good solution in theory, the new highway would have to be built over wide-ranging soils and wetlands, and through a heavily wooded area that closely bordered residential neighborhoods and schools.

The county chose WHPacific as its lead consulting engineer to provide design, surveying and construction management for the new highway.

WHPacific engineered textured concrete-block noise walls of varying heights and offsets, providing a noise barrier to nearby residents. They also designed several different types of retaining walls, including mechanically stabilized earth walls, gravity block walls, soldier pile walls in steep-slope areas prone to landslides, and walls to stabilize embankments while minimizing impacts to wetlands.

The project’s low-impact development techniques include a stormwater management strategy to control, clean and distribute stormwater along the route in a way that mimics natural conditions.

The highway gradually slopes downward to the west, allowing loaded westbound trucks leaving the quarries to use gravity and less gas. Its three roundabouts — used in place of stop signs or traffic signals — dramatically reduce stop-and-go situations, allowing truckers to save time and gas, reduce engine emissions and have a smoother ride. And residents and visitors now enjoy a safer, more pedestrian-friendly downtown.

The $13.9 million, 1.9-mile two-lane arterial not only improves traffic safety by routing truck traffic around Granite Falls, it reduces dust, noise, vibrations and traffic congestion, and was built for more than $11 million below the original estimate.

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