All five terminals at Houston airport are connected by an underground train (Subway) and the Skyway (elevated train).
The Skyway connects Terminals A, B, C, D, E and the International Arrivals Building (IAB) for passengers with connecting flights in different terminals and provides sterile airside connections. This allows travellers to travel within the airport without having to re-enter security. The service is for free and operates every day.
The Subway provides transportation between terminals while outside security (pre-security). It departs from Terminals A, B, C, D/E, and the Airport Hotel Marriott. The Subway operates daily from 3:30 a.m. to 12:30 a.m. and it's closed between 12:30 a.m. and 3:30 a.m.
All Terminals have direct access to the Subway Station and the Skywalk (Terminal D is connected with Terminal E via a walkway and the Skywalk is located on the Terminal E side of this walkway. Anyway, passengers from both Terminals have access to it.
- Subway Station is located in the Level LL of all Terminals.
- Skywalk Station is located in Level 3 of each Terminal.