The Portland Cement Association has named the winners of its recent Biennial Bridge Awards Competition. The competition, instituted in 1988, recognizes excellence in design and construction of concrete bridges.
The 2008 program attracted 42 entries from Canada and the United States, covering a variety of structure types and construction methods. All structures were completed between June 2006 and March 2008.
Winning projects were selected based on creativity, functionality and economy by a jury of three prominent bridge professionals: Edward Wasserman, civil engineering director, Structures, Tennessee Department of Transportation; Myint Lwin, director, Office of Bridge Technology, FHWA Washington, DC; and Barney Martin Jr, president, Modjeski and Masters, Inc.
This year's winners include projects in Florida and in Tennessee.
Precast concrete segmental bridge construction was used to achieve the owner's project goals for this Tampa, FL, overpass. The 5-mile-long elevated expressway needed to be built without interfering with at-grade traffic, its aesthetics had to satisfy nearby residents and business owners, and construction cost had to be within the budget. Using the span-by-span method of segmental construction, the 59-foot-wide deck was constructed on single 6-foot-diameter column bents located in the grassed 46-foot-wide median between the adjacent lanes of traffic. Simultaneous fabrication of the 3,032 segments, while the foundations and piers were under construction, shortened the construction time significantly. Full-width segments were lifted by the gantry crane or moved to the placement location over the completed spans. The new bridge met all the owner's goals, and after one year toll revenue was 25 percent more than estimates.
Project principals include Tampa Hillsborough Expressway Authority, owner; FIGG Bridge Engineers, engineer; PCL Civil Constructors, Inc., contractor and precast concrete; and CEMEX, concrete supplier.
"The designers are to be congratulated on building this difficult, but beautiful serpentine viaduct into the existing roadway section without disruption of traffic," noted the judges.
At the McEwen Drive Interchange in Franklin, TN, all traffic movement is aligned and curved to intersect at a single point. This is good for traffic, but it creates complexity for the roadway and bridge geometric design.
Engineers used high performance precast concrete bulb tee beams for the two-span bridge to minimize costs while maximizing the bridge's service life. The beams were installed in a fan arrangement, causing a variation in the length of each beam. To eliminate maintenance of expansion joints, the beams are designed as continuous with integral abutments and a fixed bent. Steel railings, attractive light poles and textured concrete piers on the bridge complement the character of the city known for its Civil War history.
Project principals include the city of Franklin/Tennessee Department of Transportation, owner; Gresham, Smith and Partners, engineer; Rogers Group, Inc., contractor; CPI Concrete Products, precast concrete; and Williamson County Ready Mix, concrete supplier.
"The designers of this urban interchange used simple framing and low-cost pre-stressed concrete beams to hold down costs," noted the jury, "while applying architectural treatments that demonstrate the flexibility of cast-in-place concrete, to send a message of welcome to the city of Franklin."