关于 inter-terminal transfer 的解释
Terminals 1, 2 and 3 are located in the main central terminal complex. Terminal 4 is on the south side of the airport.
Passengers with connecting flights should follow the Flight Connecti##被过滤## signs.
Pedestrian access between Terminals 1, 2 and 3 is by underground walkways, most by moving walkway.
On foot transfer between terminals can take up to 10 minutes so allow plenty of time.
Transfer between the central area terminals (Terminals 1, 2 and 3), and Terminal 4 is by the Heathrow Express train service. This transfer is free. Follow the signs.