The CSX Transportation Railroad Bridge in Whitmire was designed and constructed with no disruptions to regular train travel, which was one of the client’s main goals going into this project. The goal of ensuring that any interruptions to train schedules would be minimal or nonexistent was crucial for this project because this particular stretch of rail line serves as the main line between the Chester and Clinton train hub areas. Therefore, any impacts sustained along this rail line would have negative ramifications throughout the state. This line runs more than ten trains per day and any schedule disruptions would have cost the railroad valuable time in the transportation of goods and services.
One of the major project issues facing the Vaughn & Melton team was that CSXT did not want to build a bridge adjacent to the existing bridge. This would have led to logistical, cost, and scheduling issues because the traffic would have to be rerouted during construction and then would need to shift back over once the new bridge was completed. The layout and construction of rail lines do not easily allow for such shifts in alignment. So the team’s solution was to complete the bridge project in the same location as the existing bridge. The next issue to solve for was that shutting down the railroad, even temporarily, was not an option. In order to meet this critical design issue, Vaughn & Melton used rigid frame bent foundations, also referred to by CSX as their “saddle cap” design, at strategically placed locations. The end bents and piers were designed so that all drilled shaft and column construction could take place on each side of the existing bridge deck in between existing trestles. The concrete cap was then formed and constructed under the existing bridge. This method ensured that all substructure work was completed without interruption to rail traffic. After the substructure was finished and cured, the superstructure spans were assembled onsite and erected in a stoppage window of 6 to 12 hours. Once a span was set and rails reconnected, traffic resumed until time to erect the next span. This procedure was followed span-by-span until the bridge was completed, thus any disruption to the traffic was minimized along with the least amount of environmental impact to the site.
This project was awarded an ACEC South Carolina Engineering Excellence Award in 2012.