The fast rate is just one of many triumphs for the 6.2 m (20.2 ft) Robbins Main Beam TBM operating at the Indianapolis Deep Rock Tunnel Connector (DRTC). The veteran machine was originally built in 1976 and used on multiple projects, most recently on the Second Avenue Subway Project in New York City. The robust TBM has been rebuilt multiple times. The machine, owned by the Shea/Kiewit JV contractor, was refurbished and redesigned in Cleveland, Ohio and Mt. Pleasant, Pennsylvania. Its latest rebuild included a fitting with variable frequency drive motors and new components including a back-loading cutter head with 19 inch disc cutters and a rescue chamber. The TBM was launched in early 2013 and began its excavation in limestone and dolomite rock.