Consulting Civil and Environmental Engineers Since 1972

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Rehabilitation of CTDEP Bridge No. 6311 over Chatfield Hollow Brook
Chatfield Hollow State Park
Killingworth, Connecticut

THE CHALLENGE: Originally constructed in 1934, the Connecticut Department of Environmental Protection’s twin span Bridge No. 6311 carried 700 vpd over Chatfield Hollow Brook, providing the sole public exit roadway from Chatfield Hollow State Park. Extensive deterioration of the existing twin span steel stringer and plank deck superstructure resulted in a rating of "structurally deficient" by the CTDOT. A replacement superstructure was required that: enhanced site aesthetics; and, could be constructed in the spring and completed prior to opening the park to vehicles on Memorial Day. THE SOLUTION: The new bridge consisted of an AASHTO HS20 designed, pressure treated 8 3/4 inch thick longitudinal glued laminated timber slab superstructure. The 28 ft. long continuous span superstructure was set on modified bridge seats on the existing substructure. The superstructure included a 12’-3" wide travelway and a 4’-7" wide walkway separated by vehicular and pedestrian railing systems. A membrane waterproofing and bituminous wearing course were placed in the travelway. The vehicular railing system was a crash-tested design. The pedestrian railing system included wood-plastic composite rails which provided splinter free protection to pedestrians. To enhance site aesthetics, steel-backed timber guide rails were used at all approaches. All timbers were pressure treated with an oil-borne preservative and all bridge fasteners were hot-dipped galvanized. Substructure repairs included pointing of existing masonry stone walls.		CTDEP Bridge No. 6311 was closed for the construction of the new bridge, which was completed in 2000 after approximately 2 1/2 months of construction. Final construction cost was approximately $75,000. 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, shop drawing review, and periodic bidding and construction administration and inspection.

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