Ashland County STH 13 Roadway & Silver Creek Bridge

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The Wisconsin Department of Transportation, Northwest Region, retained Ayres to design the replacement of the culvert carrying Silver Creek under STH 13 in Ashland County and to prepare preliminary and final roadway plans to repair or replace decayed culvert pipes, flatten slopes, and repair existing box culverts on 18 miles of STH 13 between Mellen and Ashland. The project included roadway plan development from Golf Course Road just north of Mellen to Buttersworth Road just south of Ashland.

Ayres evaluated cost effectiveness and environmental constraints in determining the preferred structure type for the Silver Creek crossing – box culvert or bridge. Approaches were reconstructed to accommodate the preferred structure. Minor real estate acquisition was needed, and wetland impacts required delineation.

Roadway plan development for STH 13 between Golf Course Road and Buttersworth Road included agency coordination; reports; environmental document; supplemental survey; right-of-way plat; public involvement; and plans, specifications, and estimates. Seven box culverts underwent repairs for separated joints, broken wing walls, scour holes, and associated slope failure. More than 70 culverts and channel crossings were evaluated for the project. The sizes of existing channel crossings were checked against current standards, and if the existing crossing was inadequate, a recommendation was made for an adequately sized replacement crossing.

In July 2016 a flood washed out box culverts at two sites along the project. Ayres was already designing a replacement for one of them (Silver Creek) before the washout occurred, and an emergency replacement for the second (Trout Brook) was added to our project. We had surveyors on the scene within two days, and design was accelerated to get both open before the end of the year.

Ayres provided conceptual design and hydraulics services for the replacement bridge over Trout Brook. WisDOT provided final structural design.

Project Information

Client's Name

Wisconsin Department of Transportation, Northwest Region


Ashland County, WI

Primary Service

Roadway Design


State + Federal + Tribal