the Second Avenue subway...

https://en.wikipedia.org/wiki/Second_Avenue_Subway

http://web.mta.info/capital/sas_alt.html

http://gothamist.com/2016/12/21/2nd_avenue_subway_history.php

http://www.amny.com/transit/the-second-avenue-subway-explained-1.11244882

http://www.theverge.com/2017/1/2/14145396/second-avenue-subway-nyc-mta-cuomo-photos

https://www.timeout.com/newyork/travel/news-on-nyc-subway-projects-including-the-second-avenue-subway

http://repone.net/portfolio-view/second-avenue-subway-new-york/

https://www.wired.com/2016/06/get-ready-quieter-nyc-subway-stations-yes-possible/

http://untappedcities.com/2013/07/24/descending-into-the-second-avenue-subway-photos-nyc/

https://www.google.ca/nyc_sub

https://en.wikipedia.org/wiki/Platform_gap_filler

https://en.wikipedia.org/wiki/191st_Street_(IRT_Broadway%E2%80%93Seventh_Avenue_Line)

https://en.wikipedia.org/wiki/Early_history_of_the_IRT_subway#History

http://theinfrastructureshow.com/podcasts/nycs-second-avenue-subway

https://www.google.ca/search?q=new+2nd+ave+subway&safe=off&espv=2&biw=1538&bih=738&tbm=isch&tbo=u&source=univ&sa=X&ved=0ahUKEwiyp8-e46XRAhVK9mMKHZQNDewQsAQITw&dpr=1.25