Hedlund Bridge replacement

Location: Over the Kettle River, between the borders of Stevens and Ferry counties, north of the city of Kettle Falls

Owner/developer: Stevens County

Project team: Harcon Inc., general contractor; Central Pre-Mix Prestress, concrete contractor; Nicholls Engineering, structural engineer; Colville Valley Concrete, ready-mix supplier

Stevens County picked a post-tensioned concrete bridge to replace a 60-year-old steel-truss bridge over the Kettle River. The old single-lane bridge had deteriorated and was functionally obsolete. The new bridge has two lanes and spans 300 feet.

The final design strength for the bridge was 7,400 psi for the first span and 8,900 psi for the second. A 10,000 psi ready-mix concrete was used, which was challenging to design and deliver due to the concrete’s self-consolidating properties, its one-hour-plus haul times in the hot summer and its origination from a dry batch plant.

The bridge contains one of the longest single-span, pre-stressed, post-tensioned girders (nearly 203 feet long) in the state. The bridge’s girders were spliced together at an angle point, which the project team says could be a first in the country. The angled splice was needed to help compensate for a vertical sag curve that was forced into the bridge design to achieve a 10 percent grade up to state Highway 395.

The old bridge’s intermediate pier was reused for the new span. It had to be reduced in height to accommodate the deeper girder section and the cantilever had to be widened to support the new deck. County officials estimated they saved more than $1 million by reusing the pier.