At the same time, California and Arizona had been looking to replace the Old Trails Bridge, as the structure had become insufficiently narrow and too weak for post-war truck and car traffic. Highway engineers determined the retired Red Rock Bridge could serve as a more than adequate replacement. The Red Rock Bridge had previously been rebuilt and reinforced twice during the early 20th century to handle heavier and faster train traffic. The railroad had planned on tearing down the Red Rock Bridge, but instead donated the structure to the states of California and Arizona along with of right of way on either side of the bridge. This was done partially due to the cost of converting the bridge into a highway crossing being less expensive than demolishing the veteran structure. Both states began surveying and planning to rebuild the Red Rock Bridge into a new Colorado River crossing for US 66. Once planning had been completed, the state governments of California and Arizona agreed to split the cost of conversion. The tracks were removed from the bridge and a concrete roadway put in its place. On May 21, 1947, the Red Rock Bridge was reopened to automobile traffic for the first time in 31 years, this time as a dedicated highway crossing. US 66 was immediately re-routed off the Old Trails Bridge onto the Red Rock Bridge. The Old Trails Bridge was originally to be demolished but was instead purchased by the Pacific Gas and Electric Company and now carries part of a natural gas pipeline between California and Texas. In 1946, the Arizona State Highway Department began planning a major improvement along US 66 between Flagstaff and Winslow. The plan was to construct a new highway between Flagstaff and Winona to shorten the travel time and the overall distance between Winslow and Flagstaff. The project was estimated to cost around $1,300,000 (equivalent to $ in ). Originally meant to be a single contract construction project, the bypass was later divided into two separate contracts. Bidding for both construction projects were opened on January 9 the same year with a scheduled completion date of September 30, 1947. The Fisher Construction Company and Tanner Construction Company were both awarded the contracts, with Fisher to construct the first east of Flagstaff and the remaining to be constructed by Tanner. By May 10, 1946, 30 percent of the section being constructed by Fisher