Engineering Inc. - July/August 2008 - (Page 25)

A Walkway Across The Missouri PROJECT: MULTI-PROJECT FEATURE Missouri River Pedestrian Bridge, Council Bluffs, Iowa, and Omaha, Neb. FIRM: hNTB Corporation, Kansas City, Mo. O ver the past 15 years, Omaha, Neb., has undertaken a $2 billion infrastructure redevelopment of its downtown and riverfront. The project is intended to transform the once heavily industrial area into an urban center. The final piece of this transformation is the $24 million cable-stayed pedestrian bridge that crosses the Missouri River and links Omaha with Council Bluffs, Iowa, a town in the throes of its own redevelopment. The engineer of record for the pedestrian bridge, Kansas City, Mo.–based engineering firm HNTB Corp., began the design and environmental study and permitting processes in the summer of 2006. The company is responsible for the design of the entire bridge and for providing construction oversight. General contractor APAC-Kansas, Inc., of Overland Park, began construction in October 2006, and the concrete bridge is scheduled for completion in November 2008. The final product will be approximately 2,500 feet long with a 506-foot main span and two 253-foot back spans and will feature singletower pylons rising more than 200 feet above the river. The dynamic, curvilinear design begins with a sweeping curve leading to the cable-supported river spans that alternate from side to side between the main tower pylons in a graceful S-curve. “The city’s goal is to create a pedestrian bridge that promotes recreational river access, encourages economic development, emphasizes historic and cultural resources, improves wildlife habitat, improves water quality and endorses responsible flood plan management,” explains Christian J. Brown, HNTB’s associate vice president. With 150 miles of trails on both sides of the river, planners say, the bridge will be a safe and exciting way for bicyclists and pedestrians to cross the river. HNTB’s biggest challenge is to provide a signature bridge solution that stays within the team’s $24 million design and engineering budget. “The budget restrictions required that we develop a design that maximizes construction and focuses on optimizing the most important design and safety elements,” says Brown. Innovative strategies employed by the company to minimize design complexity include developing a cable-stayed structure using two planes of cables to enhance the curvilinear design, developing cost-effective solutions for simplifying the steel fabrication process with minimal variations while ensuring symmetry, avoiding the use of temporary falsework and supports for foundation and pylon construction and superstructure erection and designing a structural system with proven past performance in resisting wind- and pedestrian-induced vibrations. “We envision the bridge becoming a destination simply because of the interest created by the gently curving pathway and ever-changing vistas,” says Brown. Christian J. Brown The $24 million cable-stayed pedestrian bridge crosses the Missouri River, linking the city of Omaha with Council Bluffs.

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Engineering Inc. - July/August 2008 Table of Contents From ACEC to You News & Notes Market Watch Legislative Action Congressman Kendrick Meek Going Global 2008 Professional Liability Insurance Survey Bridging the Gap 2008 Convention Wrap Up 2008-2009 Executive Committee 2008 Fall Conference Primer Business Insights Members in the News One on One

Engineering Inc. - July/August 2008

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