The K Ingleside is a hybrid light rail/streetcar line of the Muni Metro system in San Francisco, California. It mainly serves the West Portal and Ingleside neighborhoods. The line opened on February 3, 1918, and was the first line to use the Twin Peaks Tunnel. Route description The outer terminal of the K Ingleside is at Balboa Park station, where it shares a terminal loop plus loading and unloading platforms with the J Church. The line runs in a dedicated median in Ocean Avenue as far as Ocean Avenue/CCSF Pedestrian Bridge station, then in mixed traffic to Junipero Serra and Ocean station. Surface stations are typically boarding islands located between the tracks and the outer traffic lanes. The line again has a short dedicated median on Junipero Serra Boulevard. It joins the M Ocean View at St. Francis Circle station, from where the lines run in mixed traffic to a junction with the L Taraval outside West Portal station. The K Ingleside runs through the Twin Peaks Tunnel and Market Street subway to its inner terminal at Embarcadero station. Operation The K Ingleside begins service at 5 a.m. on weekdays, 6 a.m. Saturdays and 8 a.m. Sundays, with the end of service occurring around 12:30 a.m. each night. Weekday daytime headways are 10 minutes. Weekend daytime headways are 12 minutes. Service is provided by overnight Owl buses during the hours that rail service is not running. The serves the portion between West Portal and Embarcadero, and the serves the portion between Balboa Park and West Portal. The K Owl bus runs a limited number of trips during late nights and early mornings. Prior to the COVID-19 pandemic, on weekends, service is provided by K Ingleside Bus, which runs from 5 a.m. until the start of rail service. The bus line largely follows the rail line, but it uses surface streets to parallel sections where the rail line has dedicated rights-of-way. History Market Street Railway The Market Street Railway opened a branch – built in just six days – of its Mission Street line along Ocean Avenue to Victoria Street on December 4, 1895, to serve the new Ingleside Racetrack. The line was extended to the Ingleside House (where Ocean Avenue now meets Junipero Serra Boulevard) shortly thereafter. The 1906 earthquake damaged many cable car and streetcar lines; in the aftermath, the United Railroads (URR) – successor to the Market Street