N Judah

The N Judah is a light rail line of the Muni Metro system in San Francisco, California. The line is named after Judah Street that it runs along for much of its length, and is named after railroad engineer, Theodore Judah.
Operation.
As with all Muni lines, service begins around 5 a.m. on weekdays, 6 a.m. on Saturdays, and 8 a.m. on Sundays and holidays. Daytime headways are 10 minutes on weekdays and 12 minutes on weekends.
History.
On January 10, 1998, Muni opened the Muni Metro Extension to 4th and King/Caltrain. It was originally served by a temporary shuttle service, the E Embarcadero, which ran between Embarcadero station and 4th and King/Caltrain. On August 22, 1998, the E Embarcadero line was removed and the N Judah line was extended to its place. 
A lot of service changes took place at the time when the T Third Street line began service in April of 2007. The N Judah was cut back to Embarcadero station; the surface part on the Embarcadero was served only by the T Third Street line, plus the J Church line at peak hours. The changes were unpopular with the public; they caused big delays in the Market Street subway and made N Judah riders transfer to reach the Caltrain station when they did not before. On June 30, 2007, Muni reversed several of the changes; the J Church and N Judah were put back to their previous routes.
Future plans.
Future plans, according to the SFMTA Rail Capacity Strategy, include a new subway tunnel that connects the Market Street subway to 9th Avenue. Additionally, the N Judah line will be rebuilt to run three-car trains. Further plans include a connection between the L Taraval and N Judah lines, which may run on 46th Avenue.