4 tour buses apparently idle in "pad" all day

I was told buses were idling in the pad one hour before I arrived.  Indeed, when I arrived they were all idling.  I was told they have been there all day, and idling all day.
 
It is unclear why any vehicles are allowed in this location. They appeared to be tour buses for Rush.  These buses were parked at grade with their headlights facing out. They were idling.  They were parked directly across from residences.  
 
Below is a photo of the four buses in the pad.  The following link is a video for sound.  The visual is from walking along the fence separating the public from the buses.  The sound increases as I walk by each running engine.  http://www.youtube.com/watch?v=o-0_QniycWk