Spring 2019

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.

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Page 17 of 55

Parsons. T h e I n t e r s t a t e 7 5 / I n t e r s t a t e 5 7 5 (I-75/I-575) corridor northwest of the Atlanta Beltway, or Interstate 285 (I-285), runs through a densely populated and rapidly growing section in the Atlanta, Ga., metropolitan area. This corridor currently accommodates 2 9 7 , 0 0 0 v e h i c l e s p e r d a y, w h i c h almost meets the traffic projection of 310,000 vehicles per day by 2035 per the project's environmental assessment. Several planning studies over the past 15 years have looked for economical alternatives to alleviate daily traffic congestion, increase traffic capacity, and provide a construction scheme with minimal impact on existing traffic. In the fall of 2013, a public-private p a r t n e r s h i p , d e s i g n - b u i l d - f i n a n c e contract was executed to construct reversible managed toll lanes that will allow drivers to choose to pay a dynamically priced toll to bypass congestion. The project extended from the I-285 (Atlanta Beltway)/I-75 interchange parallel to I-75 to Hickory Grove Road (approximately 17 miles) and from the I-75/I-575 interchange parallel to I-575 to Sixes Road (approximately 12 miles). The project scope included 39 bridges, two major interchanges, roadway, signing, tolling facilities, intelligent transportation systems, and all ancillary structures for the project. Flyover ramps within the I-75/I-285 interchange are up to 2827 ft long with span lengths up to 175 ft and pier heights up to 90 ft to cross numerous roadways, existing flyover ramps, and irregular terrain. Prestressed concrete girders were used on several of the interchange bridges to construct cost-effective and low- maintenance structures. North of the I-75/I-575 interchange, mainline viaduct superstructures are 39.25 ft wide with four prestressed concrete bulb-tee beams, 72 to 74 in. deep, supported on single-column hammerhead piers. Bridge lengths range from 1298 to 5981 ft to span over existing local roads, railroads, streams, wetlands, and profile NORTHWEST CORRIDOR EXPRESS LANES / MARIETTA, GEORGIA BRIDGE DESIGN ENGINEER: Parsons, Peachtree Corners, Ga. OTHER BRIDGE CONSULTANT: Heath & Lineback Engineers, Marietta, Ga. PRIME CONTRACTOR: Northwest Express Roadbuilders, a joint venture of Archer Western and Hubbard Construction Company, Marietta, Ga. PRECASTER: Standard Concrete Products, Atlanta, Ga.—a PCI-certified producer POST-TENSIONING CONTRACTOR: Freyssinet Inc., Sterling, Va. OTHER MATERIAL SUPPLIERS: Mechanically stabilized earth wall panel fabricator: Reinforced Earth Company, Atlanta, Ga.; noise barrier panel fabricator: Oldcastle Precast Inc., Newnan, Ga.—a PCI-certified producer Northwest Corridor Express Lanes by Alan Kite, Parsons Corporation Project location and vicinity map. Photo: Project location and vicinity map. All Figures: Parsons. Aerial view of a mainline bridge. Bridge 25 parallels existing Interstate 75 southbound lanes and is over 1 mile long. Photo: Aerial Innovations of Georgia Inc. 16 | ASPIRE Spring 2019 P R O J E C T

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