The building phase started on September 22, 1966, on the interchange that was to replace the intersection of Pacific Highway and Rosecrans Street. The cost of the interchange was projected to be $10.86 million (about $ in dollars). SR 109 was planned to follow Camino del Rio up to the Frontier traffic circle, where the city of San Diego would resume construction; both SR 109 and SR 209 were to be built in the future. The eight-lane freeway was projected to relieve traffic in the Frontier Street area coming from the San Diego Sports Arena. Bidding for the SR 109 contract was to begin in 1968, after the City Council endorsed the route in December 1967. Completion of both the interchange and SR 109 was planned for early 1969. An interchange was planned at Midway Drive, and the western end of the freeway was to be at Sunset Cliffs and Nimitz boulevards. The cost of the SR 109 project was estimated to be $2.3 million (about $ in dollars).