The final phase of Raleigh-Durham International Airport’s Terminal 1 reconstruction project is underway, tearing down what’s left of an old building. The project is expected to cost between $6 million and $7 million. The airport is also in the process of developing a long-term master plan, which will include a number of infrastructure projects designed to carry RDU through the next 25 years. The planning phase of the master plan is expected to be completed by early 2017. Airport crews are revamping gate, C-21, so that it can be used for either domestic or international flights. The gate will need construction of a glass hallway and another set of doors so that flyers can enter a secure area en route to passport control.