Bridge Description

Somerset, in Southern Kentucky

Tier 1 (within 1 day)

ABC: overnight deck replacement over multiple nights with one of two lanes kept open; Conventional: months

reduced traffic impacts due to modular construction; improved site constructability due to lighter deck weight with less dead load on the truss

700-ft long and 36.3-ft wide three-span continuous deck truss bridge (200 ft – 300 ft – 200 ft)

25000

Traffic management alternative, if constructed conventionally: extended detour

The two-lane bridge is heavily used by vehicular and truck traffic and provides a major north-south road for the area. Its deck was deteriorated and required replacement.

The exodermic replacement deck consists of a 4.25-inch-thick steel grid with 4-inch-thick precast reinforced concrete composite topping. The plans required that the grid be produced by a member of the Bridge Grid Flooring Manufacturers Association licensed to produce exodermic bridge decks. The steel grid was galvanized in accordance with ASTM A123, and the steel reinforcement was epoxy coated. The concrete was cast on the steel grid and fully cured prior to placement of the grid deck.The Kentucky Transportation Cabinet opted to replace the existing 33.2-ft wide bridge deck during nighttime hours, keeping both lanes open during the day and one lane open at night. Traffic was routed to one lane at 6:00 pm and opened back to both lanes at 6:00 am. The slab between floor beams (spaced at 25 ft) was removed and replaced with the full-depth deck panels. Using high-early-strength concrete allowed the joints between deck panels to be poured and opened to traffic the next morning. Precast New Jersey barrier railing was attached, and a latex-modified concrete overlay was placed.