rail line, but use surface streets to parallel sections where the rail line has dedicated rights-of-way. 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 eliminated and the N Judah line was extended in its place. A variety of service changes took place with the introduction of full service on the T Third Street line on April 7, 2007. The N Judah was cut back to Embarcadero station; the surface section 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 severe delays in the Market Street subway and forced N Judah riders to transfer to reach the Caltrain station when they previously did not. On June 30, 2007, Muni reversed several of the changes; the J Church and N Judah were restored to their previous configuration. On December 5, 2009, the N Judah was cut to Embarcadero on weekends as part of widespread service reductions. Weekend service was re-extended on October 15, 2011. After concerns from riders of constant overcrowding of the trains on the N Judah line, Muni debuted an express bus route called the NX Judah Express on June 13, 2011. Starting off as a pilot program, the NX (stylized as Nx) was intended to relieve overcrowding during rush hours every ten minutes. It follows the western end of the N Judah route from Ocean Beach to 19th Avenue, then operates nonstop from there to the Financial District where it stops at Bush and Montgomery Streets. In September 2016, Muni began running a pair of one-car shuttles between Embarcadero station and Carl and Hillway during morning rush hour to reduce crowding on the inner section of the line. A study after one month showed the shuttles had increased capacity on the inner part of the line by 18% and reduced the number of passengers unable to board overcrowded trains by 63%. In March 2018, the SFMTA board voted to shorten rush-hour headways from 7 minutes to 4 minutes, but to only use one-car trains on weekends. The changes were to take effect in the summer. COVID-19 On March 30, 2020, Muni Metro