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194
Traffic Signal Systems Operations and Design: Isolated Intersections
3. What are the respective roles of minimum green time and vehicle extension time in producing efficient
operations?
In this activity, you will see the importance of the minimum green time during the early portion of
the green indication, and how you can define the roles of the minimum green time and the vehicle
extension time to ensure efficient intersection operations. You will again observe the operation of the
southbound approach of Line Street, at State Highway 8, and make observations about the operation.
You will again consider stop bar detection, with a detection zone length of 22 feet.
Open the movie file, A33.wmv.
Figure 118 shows the controller screen for the ASC/3 database editor. Observe that the minimum green
time is set to 5 seconds for phase 4 for the first case and 10 seconds for phase 4 for the second case. The
vehicle extension time is set to 2.2 seconds for phase 4.
Figure 118.
ASC/3 Database Editor
A
ctivity
33: D
etermining
the
L
ength of
the
M
inimum
G
reen
T
ime