Geotechnology & Geotechnical Testing Play Vital Roles in Foundation for New Missouri River Bridge

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The Missouri Department of Transportation (MoDOT) opened a new $63 million Highway 47 bridge over the Missouri River in December 2018, replacing a deteriorating bridge built in 1936. The project involved building a new 2,560-foot-long bridge directly upstream (west) of the existing span.

HDR Engineering, Inc., designed the new bridge and Geotechnology, Inc., provided geotechnical services. Alberici Constructors was the contractor.

HDR Engineering designed the bridge using Load and Resistance Factor Design (LRFD) methodology. The design called for a mechanically stabilized earth (MSE) wall to be built on the south end of the bridge and a new approach embankment north of the bridge. The embankment is approximately 15 feet tall and 500 feet in length.

In 2012, Geotechnology began drilling and testing land and river borings for the proposed bridge and proposed mechanically stabilized earth wall, as well as the planned north approach embankment, and the planned approach pavement on both sides of the river. Seismic liquefaction of loose sands along the north approach embankment and lateral spreading at the north abutment during the design earthquake, were identified as geotechnical design issues.

Twelve borings were drilled to bedrock at depths of 17 to 98 feet using Geotechnology exploration rigs on a river barge. The dolomite rock was highly to slightly weathered and was cored up to 40 feet into sound rock. Because of the variable depth to rock, bridge foundations along the south shore bear on spread footings, foundations in the center of the river bear on drilled piers, and foundations on the north and south shores are supported on driven piles. Load Resistance Factor Design (LRFD) analysis and design methods were used in accordance with MoDOT’s Engineering Policy Guide (EPG). Tiered mechanically stabilized earth (MSE) walls were designed to improve slope stability at the south abutment.

The older bridge had two 11-foot lanes, no shoulders, restrictive weight limits and required a regular cycle of maintenance work. The new span has two 12-foot lanes, 10-foot shoulders and a 10-foot protected path for bicyclists and pedestrians. It also has a 100-year design life with limited maintenance and several other enhancements, including variable depth, haunched steel girders, and fluted bridge piers with architectural reveals. An overlook, where walkers and bikers can stop and view the river, is provided at the center bridge pier.

Located between Jefferson City and St. Louis, the bridge connects Warren County to the north and Franklin County to the south, a growing commercial and residential area.

“This bridge is vital to the community, with approximately 11,000 vehicles traveling on it each day,” said Geotechnology Vice President Frank Callanan, P.E., D.GE. “It was critical that thorough geotechnical examinations were conducted to ensure its safety and viability.”

Established more than 30 years ago, Geotechnology, Inc. is a professional corporation offering a comprehensive range of consulting services in applied earth and environmental sciences, including geophysics, water resource management, geotechnical and environmental engineering, materials testing and drilling. Geotechnology has provided expertise on thousands of major construction projects in the Midwest and Mid-South regions. Geotechnology is ranked #406 in ENR’s Top 500 Design Firms in 2018. Geotechnology, Inc. is based in St. Louis, Mo., and has 10 offices in Missouri, Illinois, Kansas, Ohio, Kentucky, Tennessee, Mississippi and Arkansas. For more information, visit www.geotechnology.com.

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