Los Angeles World Airports has awarded a $336-million contract to enlarge three terminals and build some infrastructure for the future people mover, an elevated train that will ferry passengers around the airport.

The people mover will also provide a direct link between the airport and Metro’s Crenshaw and Green lines via the future Airport Metro Connector 96th Street Station. People mover trains are scheduled to run every two minutes, 24/7, for free.

The terminal extension project involves building three new structures to expand the terminal space, creating room for walkways, escalators, elevators, and other installations necessary to help people move between the terminals and the people mover trains.

“These new structures will also provide space that can be used for offices, baggage claims, restrooms, airport lounges, or other airport uses,” LAWA said in an announcement.

LAWA, which operates LAX, says the extension project will enlarge terminals 5 and 6, plus the Tom Bradley International Terminal. The project is expected to begin construction in early 2019 and be complete in 2021.

Four additional terminal expansions will be built on a different timeline by American Airlines, Delta Air Lines, and Southwest Airlines at the other terminals. Those are expected to be operational by 2023, when the people mover comes online, LAWA spokesperson Charles Pannunzio tells Curbed.