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Replacement of Upper North Main Street Bridge over Great Brook
Town of Chester, Connecticut

THE CHALLENGE: The existing Upper North Main Street Bridge was a 19.5ft. clear simple span built in the 1920s. Construction had consisted of a monolithically cast reinforced concrete tee-beam and deck on masonry rubble stone abutments and wingwalls. In 1949, the superstructure was widened to one side with the addition of steel beams and concrete deck. The Connecticut Department of Transportation had determined that the bridge was structurally deficient and therefore eligible for funding through the Federal Local Bridge Program.
THE SOLUTION: The new bridge consisted of an AASHTO MS18 (HS20) designed, twin 4 m (13ft.) span by 2.1 m (7ft.) rise precast reinforced concrete box culvert. The 11.2 m (37ft.) long culvert carries a horizontally curved roadway over the Pattaconk Brook and includes cast-in-place reinforced concrete cut-off walls, return walls, wingwalls and parapets. Geometry of the project was complicated by differing box culvert end skews, horizontally curved parapet and sidewalk, u-shaped wingwalls with reverse curves, and a lowered barrel floor to meet fish passage requirements. A membrane waterproofing with bituminous protective course was placed over the box culvert prior to placing the roadway gravel. To enhance site aesthetics, all exposed faces of the parapets and wingwall stems were form-lined and color-stained. The parapet’s two-rail aluminum bridge rail system was anodized, and a steel-backed timber approach rail pressure treated with an oil-borne preservative was used at all four approaches. North Main Street was closed for the construction of the new bridge, which was completed in 2001 after approximately 7 months of construction. Final construction cost was approximately $610,000. Complete bridge engineering services were provided by Nathan L. Jacobson & Associates, Inc., of Chester, Connecticut. Project management was directed by a principal of the firm specializing in bridge design. Services included survey, planning, design, right-of-way maps, permit procurement, bidding, shop drawing review, and periodic construction administration and inspection.

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