THE CONCRETE BRIDGE MAGAZINE

SPRING 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.

Issue link: http://www.aspiremagazinebyengineers.com/i/957336

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permits prohibited in-water work from January 1 to June 30 each year, with the caveat that work occurring inside a steel cofferdam would not be considered in-water work. Once the steel cofferdams were installed for the piers, work could proceed unrestricted on the pier foundations. Construction for this project began in May 2013, and the new bridge over the Intracoastal Waterway opened to traffic on April 22, 2016. Close coordination between the design team, owner, and precast concrete industry ensured that the bridge details were resilient, efficient, and economical. This partnership with the precast concrete industry facilitated the successful construction of the project, which was completed with minimal modifications proposed by the fabricator, and maintained the desired schedule for opening the bridge to traffic. _____________ Joseph Mumber is vice president, senior technical principal, and structures department manager; David Rue is a senior supervising engineer and senior technical principal; and Steve Esposito is supervising structural engineer and senior technical principal all with WSP in Lawrenceville, N.J. Pankesh Patel is the project manager for the New Jersey Department of Transportation in Trenton, N.J. _____________ AESTHETICS COMMENTARY by Frederick Gottemoeller Since it was built more than 50 years ago, the Dorland J. Henderson Memorial Bridge has been a distinctive bridge, recognized in architectural circles as well as among engineers. It has been noted for its graceful, tapered piers as well as its innovative “string of pearls” lighting. The New Jersey Department of Transportation (NJDOT) is justifiably proud of it. The agency’s decision to keep it and build a new similar bridge parallel to it is thus a double win. The original bridge is both preserved and amplified. The aesthetic value of these bridges begins with their tapered piers. It is amazing how much the basic decision to batter the piers in both directions can improve the appearance of a structure. The reason traces back to people’s intuitive impressions of vertical structures. A structure that is wider at the bottom than at the top looks (and is) more stable, and thus seems more satisfying. Nature provides a model: tree trunks are always thicker near their bases than at their tops. (The appearance of retaining walls can be improved the same way, and for the same reason, by simply battering their faces.) A taper can get out of hand if the structure is very tall, but that can be avoided by decreasing the degree of taper. Nature again offers a model: the degree of taper of a redwood trunk is much less than on a live oak, but they are both attractive trees. The piers borrow another feature from nature: the hammerheads join the pier shafts by means of a curve. Tree branches similarly curve as they join their trunks. It is nature’s way of minimizing the higher stresses of a re-entrant corner, a problem engineers also must resolve. The team’s development of a precast concrete construction option proves that these features can be applied even with precasting, though the contractor chose not to employ that technique. Finally, NJDOT’s decision to reinstate the string of pearls lighting using modern LED technology must be very heartening to the long-time residents of this recreational area. People come to Long Beach Island to relax and enjoy the attractive natural environment. When we insert something into such environments, there is a heightened responsibility to make sure that the new object adds to, and does not detract from, that environment. The new Manahawkin Bay Bridge meets that standard.

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