ABSTRACT
ABSTRACT: Constructed in 2007, the $15 million Ramp ‘X’ Bridge project was designed by Gandhi Engineering, Inc. as the final stage of the 5-stage Hawthorne-to-Pleasantville corridor improvement process initiated by the NYSDOT approximately 25 years ago. The project is located in a narrow north-south oriented ecologically sensitive segment of the Pocantico River, and is hemmed in by State Route 9A/100, the Taconic State Parkway, a wide bikepath, and Beech Hill Road, all of them framed by the surrounding Pocantico Hills, in the town of Mount Pleasant, Westchester County, NY, about 31 miles north of Times Square in New York City. The bridge connects southbound Route 9A to Southbound Taconic State Parkway. The central feature of this project is a sharply skewed flyover bridge tightly aligned on compound horizontal alignment involving a circular arc segment joined by a tangent. The irregular curvature of the bridge’s steel framing required detailed analysis of stresses and deflections using finite element method. The average span of the curved girders is about 51 meters (167 ft) as the span follows a pronounced vertical curvature which further complicated the detailing and fabrication of superstructure. The bridge deck crosses the 6-lane State Highway 9A joining its southbound lanes with those of the Taconic State Parkway. In addition to the bridge structural work, the project required the construction of long box culverts adjacent to bridge foundations and extensive use of tall retaining walls faced with granite veneers that secure the fills of bridge approach embankments and the embankments of relocated bikepath.
