Roundabouts designed to accommodate high volumes of large-sized vehicles.
Getting the gravel going. Snohomish County needed a heavy vehicle bypass route for the City of Granite Falls. When the three gravel pits north of the City are in operation, the Quarry Road averages three dump-trucks with trailers per minute and the County needed to divert them away from the downtown area. As a subcontractor to WH Pacific, Reid Middleton was selected to provide geometric design, paving, plans, grading, channelization, and signing for three roundabouts on the Granite Falls Alternate Route (Quarry Road). The single-lane roundabouts are a three-leg (at SR 92), a four-leg (at Burn Road), and a five-leg (at Jordan/Engebretsen Road), all with high-speed approaches. To better facilitate the high rate of heavy vehicle traffic, all circulating lanes were concrete. The roundabouts were also designed to accommodate a 112-foot, 12-axle lowboy truck that makes approximately four trips to the gravel pits per year. The SR 92 roundabout required review and approval by WSDOT. Reid Middleton engineers also designed and prepared construction documents for soldier pile walls- structural earth walls that support the roadways that run through mountainous terrain and wetlands that are located in areas of high risk for potential slide hazards and pass over poor soils. The result is an alternate route that keeps the heavy vehicles and regular traffic moving.