ASPIRE is a quarterly magazine published by PCI in cooperation with the associations of the National Concrete Bridge Council. The editorial content focuses on the latest technology and key issues in the Concrete Bridge Industry.
Issue link: http://www.aspiremagazinebyengineers.com/i/740919
Ross Clark Circle is a divided four-lane highway carrying State Route (SR) 210 that coincides with U.S. Highway 231 in a circle around Dothan, Ala., in the southeaster n cor ner of the state. Originally constructed in the 1950s, Ross Clark Circle has seen average daily traffic increase from 5000 vehicles per day to approximately 40,000 vehicles per day and is expected to exceed 73,000 vehicles per day in 20 years. On the west side of the city, Ross Clark Circle crosses Beaver Creek supported by a triple-barrel, 6-ft-rise-by-10-ft-span cast-in-place concrete box culvert. This culvert, under 18 ft of fill, has serious cracking and was slated for replacement in a consultant's original contract plans to widen Ross Clark Circle from four to six lanes. The Constraining Risk The decision to replace the culvert with another was made by the state's bridge hydraulics engineer during his site evaluation and was based on the culvert's drainage history. Much development has occurred inside Ross Clark Circle without regard to water runoff or detention. This has resulted in complete immersion of the opening with upstream flooding in severe rain events because the culvert was not designed to carry the increased flow of the creek. Changing anything with regard to the culvert's cross-sectional drainage area has the potential to change downstream drainage characteristics, which could result in legal liability and civil lawsuits against the state. A culvert the same size as the existing has to be in that location. The Consultant's Dilemma Going with a new box culvert was easier said than done. In order to accommodate the additional roadway width and a 3:1 backslope, the culvert would have to be lengthened 25 ft at one end and 30 ft at the other. Above-ground water and sewer pipes at both ends within those ranges prohibited this approach. The next plan was to consider building a shorter culvert with a retaining wall running over the ends. This idea was not considered feasible due to settlement and cost issues. In addition to these problems, the culvert would have to be built in two stages—half the culvert length at a time with traffic shifts. To do this the contractor would have to drive sheet piles on both sides of the culvert for soil retention and then drive unembedded sheet piles over the culvert. These unembedded sheet piles would have to be supported laterally with whalers, which would have to be secured to sets of nested piles driven on both sides of the culvert. After stage one completion, the sheet piles and the nested piles would have to be pulled and redriven and the whalers reattached at least 10 ft away to allow for construction of stage two. The perceived cost and constructability issues presented serious obstacles to moving forward. An Innovative Solution W h e n A l a b a m a D e p a r t m e n t o f Transportation (ALDOT) structural engineers were presented this scenario, they recognized the opportunity to apply an accelerated bridge construction (ABC) innovation as the solution. They determined that although the culvert was cracked, the cracks could be corrected and the culvert could continue to carry water without further concern profile BRIDGE OVER CULVERT ON SR 210 (US 231) / DOTHAN, ALABAMA BRIDGE DESIGN ENGINEER: Alabama Department of Transportation, Montgomery, Ala. PRIME CONTRACTOR: McInnis Constructs, Montgomery, Ala. PRECASTER: Forterra Building Products (Pelham), Pelham, Ala.—a PCI-certified producer OTHER MATERIAL SUPPLIERS: Hilman Rollers, Marlboro, N.J. Typical section for northbound bridge. All Photos and Figures: Alabama Department of Transportation. 1'-2 3'-9 3'-9 3'-8" 3'-8" 60'-5" 1'-2 1 2 " 1 2 " 58'-0" Gutter to Gutter 29'-0" 29'-0" 7'-7" 7'-7" 7'-7" 7'-7" 7'-7" 7'-7" 7'-7" 2'-6" 1 2 " 1 2 " ℄ Bridge 2% Slope Bridge Barrier Rail Typical by Paul E. Froede and Brantley Kirk, Alabama Department of Transportation Bridge over Culvert on SR 210 (US 231) 26 | ASPIRE Fall 2016 P R O J E C T