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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52 | ASPIRE Winter 2018 NEXT beams, and other pre- and post - tensioned precast concrete bridge elements. MDOT has worked with PCI Gulf South to implement use of these elements in a way that is consistent with surrounding states. This standardization has allowed MDOT to purchase these elements at much lower costs. Long-Span Post-Tensioned Systems Mississippi has traditionally turned to structural steel for long-span river and railroad crossings, grade separations, and bay bridges. However, because the cost of structural steel is high and the state lacks a strong steel industry with fabrication capabilities, prestressed and post-tensioned concrete systems have become the structures of choice for long spans. On August 29, 2005, Mississippi was severely affected by one of the most devastating hurricanes to strike the Gulf Coast. Hurricane Katrina destroyed two of the state's large bascule bridges along U.S. Highway 90 in Biloxi Bay and Bay St. Louis. With replacement costs at nearly $500 million, Mississippi began developing design-build documents to replace the two bridges. This was MDOT's second design-build project after the Mississippi Legislature opened the procurement process in 2004, and the estimated cost was 100 times that of MDOT's first design-build project, the replacement of a low- traffic, rural bridge. Under a conventional, expedited design-bid- build procurement format, MDOT expected project delivery would take between three and four years. However, design-build provided a project delivery of less than two years. The Bay St. Louis Bridge was constructed by a joint venture of Granite Construction, Watsonville, Calif., and Archer Western (Walsh Group), Atlanta, Ga., with HNTB, Baton Rouge, La., in charge of the design as well as construction engineering and inspection (CEI) (See ASPIRE ® Spring 2007). The Biloxi Bay Bridge was constructed by joint venture Kiewit Massman Traylor Constructors, Omaha, Neb., as the contractor and Parsons Transportation Group, Pasadena, Calif., as the designer, with Volkert in Jackson, Miss., conducting the CEI (See ASPIRE Winter 2012). Both bridges were completed in record time with prestressed, post-tensioned concrete girders as the superstructure elements. E a c h b r i d g e i s a f i xe d - s p a n h i g h - r i s e structure composed of prestressed concrete bulb-tee girders with a multispan, haunched, post-tensioned main span unit. The decks are cast-in-place (CIP) concrete and contain pedestrian lanes that are large enough to double as inspection lanes for under-bridge inspection vehicles. The result is two aesthetically designed, long- lasting, and low-maintenance concrete bridges, which have replaced costly, high-maintenance bascule bridges. The new bridges also feature artwork from local artists. The new pedestrian lanes have become so popular with local residents that MDOT authorized a project to build a new parking area near the Bay St. Louis Bridge to make pedestrian access easier. The new bridges are higher, wider, and longer than the str uctures they replaced. The record rebuild has helped reconnect communities, restore mobility, and renew the Gulf Coast infrastructure, economy, and culture. Communities on the Mississippi Gulf Coast are now stronger , and their futures are brighter. Innovative Solutions for Local System Bridges The City of Jackson closed a local bridge, located on Robinson Road between Raymond Road and the McDowell Road Extension, after a routine inspection indicated significant scour on the southeast corner of the bridge. After the closure on February 17, 2016 , the scour caused the collapse of the end span on the three-span channel-beam bridge in March 2016. Mississippi's local system traditionally uses 19-ft- to 31-ft-long reinforced concrete channel beams, but the City of Jackson was forced to search for an alternative solution to replace the bridge when this solution would not meet the following challenges: • Existing utilities could not be moved. • The existing roadway grade could not be raised. The bridge was closed for nearly a year while city officials, the Federal Highway Administration, and MDOT's Local Public Agency (LPA) Division acquired funding and developed plans. Volkert was selected to design the replacement bridge. With assistance from the local prestressed concrete industry, a design was developed for a bridge comprised of four FIBs that span 95 ft to address the needs of this project. The deck is CIP , and the abutments are CIP caps supported by concrete piles. The cap and piling were specifically designed and located to avoid After being damaged beyond repair following Hurricane Katrina in August 2005, the new Biloxi Bay Bridge was completed in record time with prestressed concrete girder approach spans and haunched post-tensioned concrete girders for the main spans. The aesthetically designed new bridge features artwork from local artists and pedestrian lanes offering beautiful views of Biloxi, Ocean Springs, and the Biloxi Bay. The new Bay St. Louis Bridge constructed after Hurricane Katrina is a fixed-span, high-rise bridge comprised of prestressed concrete bulb- tee girders with a multispan, haunched, post- tensioned concrete main span unit. The bridge connects Bay St. Louis with Pass Christian on the heavily traveled U.S. Highway 90 corridor along Mississippi's Gulf Coast.

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