New York, NY
Tuskegee Airmen (formerly 100th Street) Bus Depot
Replacing a 108-year-old streetcar barn, the 100th Street Bus Depot opened in 2003. Shortly after construction, the elevated concrete floor slabs cracked. The contractor attempted to repair the 280,000 sq ft of elevated decks and ramps, but subsequent cracking, including some through the previous repairs, raised concern about the service life of the depot. SGH investigated the cause of cracking in the concrete slabs.
In 2006, SGH completed a field investigation to document all cracks. We used ground penetrating radar (GPR) to collect information related to the depth of the reinforcing steel and slab thickness. In our laboratory, we evaluated extracted concrete core samples. SGH concluded widespread cracking resulted from several construction issues and attempts to fill the cracks did not penetrate sufficiently.
SGH developed several options to repair the cracks. Since the facility was already in use and the decks could only be out of service for a limited time, we suggested trial applications of three repair materials at high-traffic ramps to evaluate the performance. Based on information we collected during the trial applications, we developed a remedial program providing the owner with a 75-year service life for the depot with routine maintenance.