OHL North America subsidiary Community Asphalt, Corp., was a majority partner in the joint venture, that won the $567 million design-build-finance contract in 2009—the largest interchange project in Miami at the time.
Community Asphalt reconfigured and expanded the interchange that connects SR-826 (Palmetto Expressway) and SR-836 (Dolphin Expressway). The project enhanced safety, increased capacity, and improved the efficiency of motorists using the interchange.
The scope of work included demolition of 20 bridges, construction of 46 bridges, many of which were multi-level structures. New direct ramps for major movements and collector-distributor ramps eliminated geometric and operational deficiencies. Project’s totals included 1.08 million square feet of bridge decking, 783 precast bridge segments, 738,958 square feet of MSE walls, 120 columns, 168 foundations and 2427 driven piles. The entire corridor improvement totaled 16 miles. Besides the large quantities of roadway work, improvements included relocation of the canal between NW 6th Street and NW 16th Street, as well as installation of a new drainage system to treat roadway runoff, new traffic signals, lighting, and overhead electronic devices providing up-to-date traffic advisories.
The interchange is in the glide path for Miami International Airport runways 9-27, and construction required close coordination with Miami-Dade Aviation Department and FAA to not impact airport operations. Time was also a critical factor for this project. The DBF team realized that the critical path depended on speed of construction of the segmental bridges and decided to build them “from the top down.” The crews used a 460-foot, self-launching overhead gantry to build the precast bridges in balanced cantilever over the core of the interchange that carries 430,000 vehicles per day. The overhead erection method provided safer travelling environment by eliminating the need for falsework and cranes, as well as five MOT phases that would have impacted the flow of traffic.
The project also served as proving ground for diabolos – FDOT allowed their use for the first time based on their successful application on segmental bridges in other states. Traditional bent steel pipes were eliminated, and segment weight was reduced allowing for variable tendon geometry and continuous external tension ducts. External tendons also reduced future maintenance costs through improved future access for tendon replacement, as well as upgrading and stressing of any single strand inside the box. In addition, the pier caps were designed to support the balanced cantilever during construction and include loop tendons through the caps to tie down the launching gantry and curved balanced cantilever superstructure.