Monmouth County Bridge MA-11

French & Parrello Associates (FPA) was retained by Monmouth County to provide engineering services for the replacement of Bridge MA-11 on Aberdeen Road over Matawan Creek in the Borough of Matawan, NJ. The existing structure, built in 1944 and rehabilitated in 1961, is a 46 ft. long, three-span bridge with a 26 ft. wide roadway. It consists of precast reinforced concrete adjacent slab beams supported by reinforced concrete pier caps with original timber pile bents and timber abutments. The bridge is constructed perpendicular to the roadway, with a separate timber pedestrian bridge carrying the sidewalk immediately west of Bridge MA-11.

The bridge was determined to be functionally obsolete and structurally deficient due to inadequate deck geometry and deterioration of the substructure. The proposed replacement is a 75 ft. single-span bridge with an out-to-out width of 44 ft., carrying two 12 ft. lanes, two 5 ft. shoulders, and one 6 ft. sidewalk. The superstructure consists of pretensioned prestressed concrete AASHTO I-beams supported by full-height concrete abutments on pile-supported foundations. Roadway improvements extend 0.36 miles along Aberdeen Road, widening the roadway from 28 ft. to 34 ft.

The existing low point of Aberdeen Road is at elevation 3.94 ft. and is susceptible to frequent tidal flooding. To increase resiliency, the project proposes to raise the roadway by approximately 1 ft. above the FEMA flood elevation, with a proposed low point of 14 ft. Due to highly compressible soils, ground improvements using a Column Supported Embankment System are necessary to mitigate settlement. Without these improvements, post-construction settlement was estimated to range from 12 to 18 in. The project also includes installation of more than 2,000 linear ft. of anchored high modulus steel sheet pile walls to retain the widened and elevated roadway embankment.