# Signal Coordination Example II by malj

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SIGNAL COORDINATION
More Examples
Signal Coordination – Example II
Signal Coordination Example II
   Find the offset for a link 1,500 ft, Given:
 platoon  speed = 40 fps
 discharge headway = 2 sec/veh

 start-up lost time = 3 seconds

 When
a.   No standing queue at downstream
b.   Standing queue of 8 vehicles per lane
(a) Without Queue
   Offset = tideal = L/S
 L: distance btw signalized intersections
 S: average vehicle speed (fps)

   Offset = 1500(ft) / 40 (fps) = 37.5 seconds
(b) With Initial Queue
   Offset = L/S – (Q×h +tL)
 Q:  # of vehicle of queued vehicle = 8
 h: discharge headway = 2 sec/veh
 tL: start-Up Lost Time = 3 sec.

   Offset = (1500/40) – (8×2+3) = 18.5
More Thoughts
   When there is queue at downstream
 Offset< OffsetIdeal
 Need to turn on the green early enough
→   Queue can disappear
Signal Coordination – Example III
RP&M 26-7
   You have two intersections 3,000 feet apart and
have achieved some success with a 50-50 split, 60-
second cycle length, and simultaneous system.
a)   Draw a time-space diagram and analyze the reason
b)   A developer who owns the property fronting the first
2,000 feet of the subject distance plans a major
employment center. She plans a major driveway and
recommendation, and why?
Solution (a)
   Progression Speed = 3000 /
60 = 50 fps = 34.0 mph
   The progression speed is                 distance
reasonable for arterial
speeds
   Bandwidth, BW = 30 sec         3000 ft
   Bandwidth Efficiency EffBW =
(BW/C) × 100% = 50%

time
30 s
Cycle Length
Solution (b)
   Assuming progression speed
of 34 mph is representative                                     Red time for driveway
of average speed, the ideal               distance
location would be at the mid-
point, or 1,500 ft from the
first intersection
   This allows the maximum
3000 ft

green for the major driveway
without affecting the
bandwidths of the arterial
progression
time
Red time for arterial
30 s
corresponds to green
time for major                             Cycle Length         Feasible greens for
driveway                                                             driveway

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