1962 when the two sections converged at the 455-mile peg, and was officially opened on 1 September. Completion of the sealed road resulted in increased tourist traffic, and a longer tourist season. A large cyclone swept through the Carnarvon area in February 1961, causing much devastation to the road network. Many floodways were completely washed away, and North West Coastal Highway was immersed in flood water for either side of Onslow. Carnarvon was cut off from general traffic for two weeks, and the damage to the roads in the region took months to repair. Approval was given to realign the road further inland, where it would be less susceptible to flooding. By the 1960s North West Coastal Highway had become a crucial connection for development in the Pilbara – including the pastoral industry, tourism, and the emergence of iron ore mining. In 1966 the traffic volume was up to 125 vehicles per day, and the unsealed road needed constant maintenance to cope with this demand. There were also frequent delays due to flooding. In 1966 the state government announced that the sealed road would be extended to Port Hedland, over a nine-year period. Substantial portions of the highway would also be relocated above the flood plain. The new alignment on higher ground would be shorter, and would make bridging rivers easier. Work started at Carnarvon, and had been completed by 1969. Locally available material was used to great extent during construction, with techniques adjusted based on what was available; however, some resources were transported across vast distances. Water, scarce in the dry climate of the North West, was conveyed up to , aggregate up to , and bitumen up to . The project required thirty bridges, over riverbeds that could be dry all year, but might receive as much as of rainfall in three months, as had been the case at Onslow in 1961. The bridges were designed to withstand twenty-year floods, but more severe possibilities were anticipated – the approaches were built lower than the bridge decks, so that excess water would flow around the bridges, rather than over them. The sealing of North West Coastal Highway was nearing completion in 1973; additional resources provided to complete the work resulted in the final section, Port Hedland to Roebourne, being finished in only five months. An official opening ceremony was held at South Hedland on 6 December 1974, with the