In 1972, a lawsuit was filed against
Caltrans over the construction of Interstate 105, and a preliminary injunction issued by the judge halted construction on the freeway until the project complied with the
National Environmental Policy Act of 1969 and the
California Environmental Quality Act of 1970. In 1979, Caltrans signed a
consent decree to allow construction of the fiercely opposed Century Freeway (
Interstate 105), which included provisions for a transit corridor in the freeway's median as a way to help communities impacted by the new freeway. Construction began in 1987 on the corridor as a light rail line, envisioned as a connection with the bedroom communities in the
Gateway Cities along the Century Freeway with the then-burgeoning aerospace center in
El Segundo. The section in El Segundo would be fully elevated and follow the route of the
Harbor Subdivision. From the beginning of the project, several compromises were made. Because Caltrans dropped a plan for the freeway to cross through Norwalk to Interstate 5, the line was denied a connection to the then-new Metrolink station. The collapse of jobs in the area and the compromises made during construction limited the line's utility, earning it the nickname "the train to nowhere." Ridership on the C Line has not been as high as the A Line, although it did have higher ridership than the
L Line (then known as the Gold Line) until 2013. and have been known for having sanitation issues; escalators are also often out for maintenance or, with the C Line in particular, only available downward.
Overhead line replacement Beginning on August 12, 2023,
Los Angeles Metro began a multi-phased project to gradually replace the aging
overhead lines on the almost 30-year-old C Line. This will involve closures on segments of the line at different time periods. The first of these closures ran from August 12 to August 19, between and stations, and August 20 to September 24 between Redondo Beach and stations. Service was replaced in the meantime by
temporary bus shuttles. The debate over service patterns proved somewhat contentious, as the final pattern must balance the needs of riders, operational needs, and the political constituencies of Metro's board members. In 2018, with the line then scheduled to open within the year, the Metro Board of Directors overrode a recommendation by operations staff that would've had a single line operating between Expo/Crenshaw and
Norwalk station. Passengers from the Redondo Beach area would have been served by a shuttle to the LAX area, where they would need to transfer to another train to continue east or north. Instead, board members approved a one-year pilot of a configuration that would combine an Expo-to-Norwalk line with another line that would connect Redondo Beach with
Willowbrook/Rosa Parks station, allowing transfers to the A and J Lines. The approved plan would incur higher operating expenses, but board members argued it would retain better transfer opportunities for
South Bay residents. Ongoing construction delays led to a reassessment of that plan in 2022. Metro recommended public outreach aimed at reformulating the operating plan before the connection to the C Line opens in 2023; in March 2023, Metro indicated that it would recommend Option 2 in the figure above, in which the K Line would run north–south from Expo/Crenshaw to Redondo Beach, and the C Line would run from Norwalk to LAX. On June 22, 2023, Metro's board of directors officially approved the implementation of
Option 2 based on staff recommendation and public opinion. In preparation for the opening of the
LAX/Metro Transit Center, Metro initiated a service change on November 3, 2024, with the opening of
Aviation/Century station. The C Line was redirected from its alignment west of
Aviation/Imperial station running to
Redondo Beach station to Aviation/Century station. The segment between Aviation/Century station and
Redondo Beach station became part of the K Line. == Future developments ==