Construction of the Yuan 70bn ($US 11.3bn) airport is due to start next year and be completed in 2018. It will have six runways for commercial flights and a seventh for military use. The airport is forecast to carry 45 million passengers a year initially rising to 70 million by 2025 and will bring much needed relief to Beijing Capital airport which handled 82 million passengers last year and is expected to reach saturation within two years.