The stations at 86th and 72nd Streets were mined. This was challenging, given the number of expensive high rise properties in their vicinities. The 96th Street cut-and-cover station was about deep, making it one of the shallowest stations being built on the line; the shallowness was so that the new line could align with the preexisting piece of subway tunnel built in the 1970s between 99th and 105th Streets. Stations at the two mined stations are between deep in rock. The construction method that was used was supposed to ease concerns for buildings above the station sites, because only two shafts were required for excavation.