In 1929 the state decided to build a new bypass of the central portion through Piru Canyon, and to upgrade the north portion over Tejon Pass and down the hill to Grapevine. This Ridge Route Alternate, or Ridge Alternate Highway, shortened the route by and increased the minimum curve radius from . This was done for the safety of the road, which had many accidents, and to increase the road's capacity. The old highway was to be relinquished to Los Angeles County and incorporated into the county road system. Construction began in 1930, and the road south of Tejon Pass opened on October 29, 1933; replacement of the Grapevine grade was completed in 1936. The three-lane road, with a center suicide passing lane, cost $3.5 million (about $ in 2019), paid for by the state gas tax. It was estimated that it would pay itself off in 2.5 years with the savings in time and gas. A new bypass of the Newhall Tunnel, through Weldon Canyon, had opened on May 28, 1930, giving drivers a better route all the way from Los Angeles to Bakersfield. The roadway was widened to an expressway by 1952 at a cost of $13.5 million (about $ in 2019), with two lanes in each direction and a center median, but still with at-grade intersections.