Originally Posted by
Moderator2
Can't explain the beep, but I believe they exist to track shuttle buses. The airport has a lot of restrictions on buses.
This.
The airport will fine shuttles if they make excessive laps before leaving with passengers. I had a Shuttle Driver tell me if he makes more than 2 laps he gets fined $35 by the airport. I'm assuming it beeps because it uses the same system as FastTrack.