to better align with BART's late-night service. J Church service resumed subway service on February 19, 2022. Future Several further expansions have been proposed. SFMTA has studied extending the Central Subway as an above-ground light rail line through North Beach, and into the Marina district, with the possibility of eventually terminating in the Presidio. A project to grant the M Ocean View its own separated right-of-way called the Muni Subway Expansion Project, building off of a 2014 SFCTA study, has received preliminary engineering studies by the SFMTA as of 2018. The project would extend the Muni subway service in a tunnel under 19th Avenue, providing grade-separated service from Embarcadero station to a proposed Parkmerced station. The 20-year Capital Plan for the SFMTA, released in 2017, also listed both a Geary Light Rail project (a surface-subway light rail line to the Richmond District via Geary Boulevard) and a Geneva Avenue Light Rail project (a light rail line connecting Balboa Park station to the terminus of the T Third line). Infrastructure The Muni Metro system consists of of standard gauge track, seven light rail lines (six regular lines and one peak-hour line), three tunnels, 12 subway stations, 25 surface stations, and 87 surface stops. The backbone of the system is formed by two interconnected subway tunnels, the older Twin Peaks Tunnel and the newer Market Street subway, both controlled by automatic train operation systems to run trains with the operators closing the door to allow the train to pull out of a station. This ATO system was upgraded in 2015 to replace outdated software and relays. The tunnels, in total length, run from West Portal Station in the southwestern part of the city to Embarcadero Station in the heart of the Financial District. Three lines—the K Ingleside, the L Taraval, and the M Ocean View—feed into the tunnel at West Portal, while two lines, the J Church and N Judah, enter at a portal near Church Street and Duboce Avenue in the Duboce Triangle neighborhood. Two lines, the N Judah and T Third Street, enter and exit the tunnel at Embarcadero. An additional tunnel, the Sunset Tunnel, is located near the Duboce portal and is served by the N. The interconnected tunnels contain nine subway stations. Three stations—West Portal, Forest Hill and the now-defunct Eureka Valley—were opened in 1918 as part of the Twin Peaks Tunnel, while the other seven—Castro Street, Church