Montague Street Tunnel

The Montague Street Tunnel is a rail tunnel of the New York City Subway under the East River between the boroughs of Manhattan and Brooklyn, connecting the BMT Broadway Line and BMT Nassau Street Line with the BMT Fourth Avenue Line. The R train uses the tunnel at all times, the N train uses it during late nights, and several W trains in each direction also use the tunnel during rush hours. All of these services use the Broadway Line; the tunnel's connection with the Nassau Street Line has not been used in service since 2010. The tunnel was constructed as part of the Dual Contracts expansion of the subway system, and opened in 1920. After being heavily damaged by flooding caused by Hurricane Sandy in 2012, it was closed full-time from 2013 to 2014 to be reconstructed.

Tunnel data from Wikidata (CC0). Summary from Wikipedia (CC BY-SA).