[2] The main argument for its construction was that a tunnel providing an additional opening on the north would lessen the constantly increasing traffic (horses, buggies and wagons), which was causing a dangerous jam at the corner of First and Spring Streets.

The roadway was lowered to decrease the grade, wood block flooring was installed to provide a noiseless surface for the traffic of teams and automobiles, and a false roof built inside the original shell.

The concrete archway of the Broadway Tunnel was 20 feet (6.1 m) high, and the entire bore was lined with white glazed tile.

The stairway on the outer face of the southern portal was extended to a rise of 65 feet (20 m) to Fort Moore Hill.

Due to the importance of the artery of travel, through which thousands of automobiles, teams and pedestrians would be passing daily, an event was held on Saturday, February 19, formally turning the tunnel over to the city, with the Automobile Club of Southern California in charge.