One of the most noticeable features of Phoenix's 6 week old light rail system is that it does not stop at the airport. The decision to bypass was made because of the cost of tunneling under existing roadways, and the impossibility of grade intersections with these roads. So instead, there's a shuttle bus from the terminal that takes passengers to the rail line.
Ridership was initially projected at 600 for the rail link, but is coming in about 40% higher, representing nearly 1% of all airport passengers. In 2013, a new automated people mover will replace the current shuttle buses.