The Muni Metro subway did much to improve downtown movement when it replaced surface running along Market St. in the early 1980s.  Still, with five lines using it, travel could be subject to operational issues. 

In the earlier years of the subway, trains often consisted of cars that joined together or were separated at the stations just beyond the two portal areas.  With a new class of vehicles, and with signaling improvements under downtown and track reconfiguration beyond Embarcadero, that practice ceased.  Normal operation is now generally efficient. 

Heading southwest, Muni shares with BART the tube and the upper concourses  of the first four stations.  Muni tracks are one level below, and BART, two.  After BART veers off, there are three more stops in the subway.  During this stretch two light rail lines, the N-Judah and J-Church, branch off to reach the surface at Duboce. 

The route for the remaining three lines transitions underground past Castro into the much older Twin Peaks Tunnel.  There is one further subterranean stop at Forest Hill before the West Portal station marks the beginning of surface operation.  Just beyond that station the L-Taraval turns off to the west.  The other two lines, K-Ingleside and M-Ocean View, continue along West Portal Ave. 

The two closely spaced trains in this photo are at the Civic Center station.