Originally Posted by threeoh

The "TTB" bus (airside between T1, T3, T5) returns March 1:

https://www.flyertalk.com/forum/34926532-post352.html

Pickups are at B1 in T1 and M13 in T5, plus some pickups in T3.

Sounds like you can go both directions, so if arriving domestic or pre-clearance in T5 you could hop right on, or if arriving int'l you could choose to re-clear TSA in T5 and take the TTB instead of taking ATS (landside train) and clearing TSA in T1/T2/T3.

Hours are 11:30-21:30.