ST9304-CS010906To: Glenn Hollowell From: Teresa Turner
Fax: Pages:
Phone: Date: 09/06/01
Re: RR Preemption CC:
[] Urgent [] For Review [] Please Comment [] Please Reply [] Please Recycle
Glenn:
Based on my understanding of how the RR signal operates and the distance between the
tracks and Beltline Road, I believe that the 20 second warning is sufficient to clear the tracks
(see attached timeline). I have assumed a Preempt minimum green time of 4 seconds for
phases 2 & 6, a ROW transfer time of 4 seconds (3 yellow and 1 all red), and a 5 second
track clearance interval for phases 4 & 7. There should only be enough distance between the
tracks and Beltline Road to store approximately 3 vehicles. These should be able to clear out
in the 8 seconds (5 seconds green and 3 seconds yellow) provided during the track
clearance interval. In addition, I have assumed that the pedestrian indications go to a steady
Don't Walk at the beginning of the Preempt minimum green interval. This has the potential to
'trap' a pedestrian in the intersection however, this movement should be very light at these
locations. Look this over and see if you are in agreement. If not, let me know and I will go
back to the drawing board.