Initially constructed to bypass the grades of the street's namesake Bunker Hill, one bore of the dual-bore tunnel served as the roadway of Hill Street while the other facilitated streetcars and interurban trains via a double track dual-gauge railway.
[1] The rail bore was built by the Los Angeles Pacific Railroad and was opened for traffic on September 15, 1909.
[2][3] The company rebuilt five miles (8.0 km) of their track as standard gauge the night before the tunnel's opening.
[8] The Los Angeles Railway ran streetcars through the southern tunnel starting in July 1939.
[1] The northern tunnel was partially filled with dirt and remained unused until 1967 when part of it was excavated and turned into underground storage for the rebuilt Los Angeles Unified School District offices on the surface.