In 1972, Muni began planning a long-proposed extension of the J Church line along San Jose Avenue (a section of which was built along the former Ocean View Branch through the Bernal Cut) to Balboa Park. The extension was intended to provide transit service to the Outer Mission, allow J Church and N Judah trains to access the carhouses via San Jose Avenue rather than a roundabout route via the K Ingleside line, and allow future through-routing of the J and M lines. Construction on the extension began in January 1989, but was delayed by the earthquake later that year. On August 31, 1991, J and N streetcars began using the extension to access the yards, thus providing revenue J service to Balboa at limited hours. Full-time revenue service began June 19, 1993.