THE CONCRETE BRIDGE MAGAZINE

WINTER 2018

ASPIRE is a quarterly magazine published by PCI in cooperation with the associations of the National Concrete Bridge Council. The editorial content focuses on the latest technology and key issues in the Concrete Bridge Industry.

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At the ground-breaking ceremony inaugurating the construction of the n e w Tr u n k H i g h w a y 1 0 1 B r i d g e reconnecting the cities of Chanhassen and Shakopee in Minnesota in June 2014, flood waters rose above the existing elevated roadway. As the r i s i n g w a t e r s s l o w l y a p p ro a c h e d the ceremonial mound of soil that had been put in place to signify the breaking of ground on the project, they demonstrated why the project was needed. A flood-mitigation study was performed in 2011 to investigate ways to improve local and regional mobility during seasonal flooding events of the Minnesota River, which would force closures of the highway. This crossing and the neighboring Trunk Highway 41 crossing in Chaska, Minn., had closed several times in the recent past, with closure times ranging from several days to several weeks and a projected cost to travelers of $1.675 million per day in 2030. The final design concept needed to minimize the risk of flooding without causing an increase in the 100-year floodplain elevation. A 4225-ft-long bridge across the Minnesota River floodplain was determined to be the preferred concept for mitigating flood risks by raising the bridge above the 100-year flood elevation and removing the existing causeway. The new bridge would provide four 12-ft-wide lanes for traffic, 8-ft-wide shoulders, and a 10-ft-wide multiuse trail separated from traffic to connect regional trails. With a bridge being selected as the preferred concept to address flooding risks, an optimal bridge type that met all of the project requirements had to be determined. To arrive upon an optimal solution to span the floodplain, various combinations of substructure and superstructure types along with span configurations were considered as the final horizontal alignment and vertical profile were also being determined. Most of the water runs off the ends of the bridge into ponds where it is treated. Scuppers were provided at select locations to prevent ponding. Pier Concept and Design Selecting a pier concept to span the w i d e M i n n e s o t a R i v e r f l o o d p l a i n that minimized cost, schedule, and environmental impacts was of first importance. Open pile-bent piers are commonly used in Minnesota for bridges over streams and wetlands because they are cost-effective and relatively easy to build. Unlike typical concrete piers, open pile-bent piers do not require any temporary works be placed in the water to construct the profile TRUNK HIGHWAY 101 BRIDGE / CHANHASSEN AND SHAKOPEE, MINNESOTA BRIDGE DESIGN ENGINEER: Minnesota Department of Transportation, Oakdale, Minn. PRIME CONTRACTOR: Ames Construction, Burnsville, Minn. PRECASTER: County Materials Corporation, Janesville, Wis.—a PCI-certified producer OTHER CONSULTANTS: Geotechnical engineer: Dan Brown and Associates, Sequatchie, Tenn.; Roadway engineer: Short Elliott Hendrickson Inc., St. Paul, Minn. TRUNK HIGHWAY 101 BRIDGE by Paul Gronvall and Benjamin Jilk, Minnesota Department of Transportation The existing causeway along with the temporary trestles served as a working platform during construction. Note the difference in the new and old roadway elevations. Completed Trunk Highway 101 Bridge. All Photos: Minnesota Department of Transportation. 18 | ASPIRE Winter 2018 P R O J E C T

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