Bridge Description

CR 98 (Kia Boulevard) over I-85 in Troup County in west central Georgia

Tier 6 (longer but reduced by months/years)

ABC: 16.5 months of I-85 shoulder closure ; Conventional: 30 months of traffic impact

reduced traffic impacts; reduced onsite construction time; improved work-zone safety

384-ft-long and 119.25-ft-wide four-span prestressed bulb tee girder bridge (60 ft – 132 ft – 132 ft – 60 ft)

31000

Traffic management alternative, if constructed conventionally: extended use of detour

Each of the three interior substructures consists of eight 3.5-ft-square precast columns with four 4-ft-square precast pier caps joining two columns each. Abutments were conventional cast-in-place backwalls and wingwalls on steel H piles. The conventional superstructure cross-section consists of fourteen 72-inch-deep pretensioned bulb tee girders at 8.5-ft spacing in the 132-ft spans, and twelve AASHTO Type II pretensioned I-shaped beams at 8.5-ft spacing and 72-inch-deep bulb tee girder fascia beams in the 60-ft-long spans. Decks were cast-in-place after beam erection.

The precast caps and columns were fabricated offsite in a controlled environment, shipped to the site using conventional semitrailers, and temporarily stored onsite after delivery. The contractor closed one lane of I-85 and offloaded up to four columns and pier caps at a time. Lane closure was kept to a minimum, normally for 1.5 hours or less, and occurred during non-peak traffic hours. Cast-in-place column footings were constructed ahead of time with protruding reinforcing steel that fit into a specialized coupler on the bottom of the columns. A bed of high-early-strength grout was placed on the footing to receive the column, the column was erected, and additional specialized grout supplied by the manufacturer was hand pumped into the coupler’s inlet holes. The columns were then checked for alignment with surveying equipment. Two columns per day were set early in the project, increasing to four columns per day as experience grew. The pier caps were placed on top of the columns similar to the way the columns were set on the foundations except that the specialized couplers in the pier cap were required to simultaneously line up with reinforcing bars from the two adjacent columns. A steel jig was placed on top of the neighboring column as they were set to ensure proper alignment. Once the alignment was checked with the jig, the contractor was able to set one interior substructure (four pier caps) in one day.The Request for Proposal special provisions for this design-build project included an innovative contracting approach requiring the contractor to propose state-of-the-art methods to achieve specified performance goals, therein providing innovative recommended methods for monitoring and reporting various performance measures to achieve the Highways for LIFE goals. The Georgia DOT required the contractor to define the performance measure methods as project deliverables tied to an incentive-disincentive approach, which is unique in Georgia. Execution is as enforceable as any other deliverable in the contract. Data reporting assessment will help determine the performance measures for future Georgia DOT construction contracts.

The project showed that the use of precast elements was a viable technique for bridge construction. In particular, the grouted rebar splices worked very well. The Department will use this technique on other bridges as the need arises.