was completed. The road was paved after World War I, and several blind turns were opened up ("daylighted"). Even with these improvements in the 1920s, it became clear that a new route was needed to keep up with increasing demand. In 1927, plans were drawn up for a "Ridge Route Alternate", named as it was planned as an addition to the existing Ridge Route and not as a replacement. It opened in 1933 as a three-lane highway through the mountains. The middle or "suicide lane" was used as an overtaking lane for cars in both directions. This route was a great improvement, faster and shorter than the old Ridge Route, but was not enough to satisfy demand, and a conversion to a four-lane expressway was needed. The outbreak of World War II delayed this until 1948 and the fourth lane was completed in 1952. However, just three years later, plans were begun for converting the four-lane expressway to a six-lane freeway. The last major alteration to the Ridge Route began in the early 1960s. By then, the plan for a six-lane freeway had expanded to eight lanes. This construction project made the most changes to the route. Many of the curves that followed the mountainside were cut through. To climb the mountain on the south side of Castaic more easily, traffic lanes were reversed (southbound lanes to the east and northbound lanes to the west). To prevent head-on collisions, the two ends of the route were separated on two different mountainsides, and the section through Piru Canyon was moved to an entirely new alignment to make room for Pyramid Lake. The project was completed by 1970 and brought the Ridge Route to its current alignment. San Joaquin Valley When the Interstate Highway System was created in 1956, there was discussion about which way to route the interstate through the San Joaquin Valley (Central Valley). Two proposals were considered. One was to convert the Golden State Highway (US 99, later SR 99) into a freeway. The other was to use the proposed West Side Freeway (current Interstate 5). The Golden State Highway route would serve many farming communities across the San Joaquin Valley, but the West Side Freeway proposal would bypass all the Central Valley communities and thus provide a faster and more direct north–south route through the state and so was eventually chosen. Construction began in the early 1960s. There