 Meanwhile , the tunnel boring machine dug at a rate of approximately 50 feet ( 15 m ) per day . The machine finished its run at the planned endpoint under 65th Street on February 5 , 2011 . S3 partially disassembled the TBM and backed it out of the tunnel . It was repositioned in the east starter tunnel to begin boring again . Because the east side of Second Avenue has some soft ground not compatible with the Robbins TBM , ground @-@ freezing was undertaken to prepare the soil for the TBM . On March 28 , 2011 , S3 , having completed its task of completing the 7 @,@ 200 @-@ foot ( 2 @,@ 200 m ) west tunnel to 65th Street , began drilling the east tunnel , with the first 200 feet ( 61 m ) being through soil frozen by S3 using calcium chloride solution fed through a network of pipes . The TBM drilling the east tunnel will negotiate the curve onto 63rd Street and break through the bellmouth at the existing 63rd Street subway station . The portion of the west tunnel remaining to be created will be mined using conventional drill @-@ and @-@ blast methods , because the curve S3 construction teams would have to negotiate is too tight for the TBM . On September 22 , 2011 , the TBM completed its run to the Lexington Avenue – 63rd Street station 's bellmouth . 
