Allen Street Bridge

Client: Washington State Department of Transportation

Project location: Kelso, Washington

Project cost: $14 million

 

DMJM Harris provided structural engineering services for a replacement of the Allen Street Bridge, which originally carried two lanes of traffic and pedestrian sidewalks over the Cowlitz River between East and West Kelso and Longview. The old bridge consisted of three 169-foot steel truss spans, one 111-foot steel truss movable span, and two 41-foot concrete approaches for an overall length of about 700 feet. Initial phases involved performing an analytical estimate of the fatigue life of the existing steel bridge, inspection and materials testing.

 

The new structure is elevated over the railroad tracks at the east end of the bridge to eliminate safety concerns with at-grade crossing of the old bridge. DMJM Harris coordinated with the Burlington Northern Santa Fe Railway on issues including vertical and horizontal clearances, construction staging, mutual use of the railroad’s right-of-way, and railroad funding for part of the bridge project. Under the second phase of the project, DMJM Harris conducted a design study and prepared a National Environmental Policy Act environmental assessment; a scour analysis; and a type, size, and location design report. DMJM Harris prepared the plans, specifications, and estimates for the new bridge. All stages of the project involved coordination with Kelso, Longview, Cowlitz County, and the Washington State Department of Transportation.