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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In 2010, the Massachusetts Bay Tr a n s p o r t a t i o n A u t h o r i t y ( M B TA ) determined that two, century-old rail bridges over the Neponset River had reached the end of their fatigue service life. The bridges, which are on the Fairmount commuter line, connect the Fairmount and Readville stations in the Hyde Park neighborhood of Boston. Both bridges were structurally deficient, with fatigue ratings below statutory limits, but replacing them posed several challenges. There had to be a minimum disruption of traffic, which required a phased construction plan. Work needed to be done quickly under tight constraints at the site, without fouling the adjacent track. The new structures were to require minimal future maintenance, with no fatigue concerns. Given these constraints and economic considerations, the design engineer proposed a long-span, precast, prestressed concrete New England bulb-tee beam bridge. This type of bridge reduces material costs, future maintenance, and environmental impact, while also improving aesthetics in the surrounding area. The bulb-tee beam optimizes the strength- to-weight ratio, maximizing the carrying capacity for live loads. At the same time, the wide top flange of the bulb-tee beam eliminated the need for formwork when profile FAIRMOUNT LINE BRIDGES / BOSTON, MASSACHUSETTS BRIDGE DESIGN ENGINEER: The Louis Berger Group Inc., Morristown, N.J. PRIME CONTRACTOR: S & R Construction Enterprises Inc., Newton, N.H. GEOTECHNICAL ENGINEER: GEI Consultants Inc., Woburn, Mass. PRECASTER: Northeast Prestressed Products LLC, Cressona, Penn.—a PCI-certified producer OTHER MATERIAL SUPPLIERS: High load multi-rotational bridge disc bearings, The D. S. Brown Company, North Baltimore, Ohio Commuter rail train (inset) passing over one of the new bridges. All photos: The Louis Berger Group Inc. by Aboud Alzaim, Malek Al-Khatib, and Daniel Deng, The Louis Berger Group Inc. Rehabilitating Boston's commuter rail line FAIRMOUNT LINE BRIDGES 20 | ASPIRE , Spring 2014 P R O J E C T AspireBook_Spr14.indb 20 3/21/14 2:20 PM

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