total in length. The contract included a $58 million option to dig three tunnel pits and three emergency shafts and to complete an open cut. The TBMs, which could dig through several types of earth, were the first such machines to be used in the New York City area. The two TBMs began digging on the Queens side in April 2011. On December 22, 2011, breakthrough was achieved in Tunnel "A" of the four Queens tunnel drives from the 63rd Street Tunnel bellmouth. By July 25, 2012, all four Queens tunnel drives were complete. In April 2014, contracts were awarded for the final modifications for the tunnels, as well as for communication systems. The project also added two bypass tunnels for Amtrak trains within Harold Interlocking. While eastbound Amtrak trains to New England would be able to go through the interlocking without crossing the paths of East Side Access trains, westbound Amtrak trains to Penn Station would use tracks that intersected East Side Access tracks. East Side Access trains to Grand Central came from the east and would diverge to the northwest while Amtrak trains to Penn Station came from the north and would continue west, so the final environmental impact statement called for a bypass for westbound trains. Around $295 million was allocated for the bypass in 2011, and work on this project started in 2013. However, by October 2015, the tunnels were behind schedule because Amtrak and the MTA could not cooperate on track access schedules. These delays ultimately raised construction costs by almost $1 billion as of April 2018, and in a report that month, the MTA attributed the delays to a lack of cooperation on Amtrak's part. The work at Harold Interlocking also included the installation of a microprocessor-based signal system, replacing the old track circuit-based signal system. In July 2018, workers started realigning tracks to make way for the construction of the Queens tunnel portal, which was the final major contract not underway at the time. The realignment of the three westbound Main Line and Port Washington Branch tracks, as well as the construction of a new eastbound Main Line track to replace an existing track, were completed by the end of summer 2018. The last major construction contract—$60 million to move tracks in Harold Interlocking and build a tunnel portal structure for Tunnel B/C—was awarded to Skanska in October 2018. Work on the tunnel