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Subproblem 5b - Page 2 of 7 |
ID# C305B02 |
Sub-problem 5b:
Three-Phase
Traffic Signal Control with a Protected Westbound Left Turn
Step 2: Results
The signalized
intersection operational procedure requires a full specification of the
signal timing plan as input data. Appendix A to HCM Chapter 16 provides some
guidance on timing plan development. Three timing plan strategies are
mentioned in the HCM:
-
Equalizing the degree of saturation
among the critical movements on each phase.
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Equalizing the delay among the critical
movements on each phase.
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Minimizing the total delay to all
vehicles using the intersection.
Each of these strategies
was applied to the intersection in question. To facilitate comparison of the
effect of the strategy, the cycle length was fixed at 120 sec. The results
are summarized for comparison in Exhibit 3-39.
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Exhibit 3-39. Three-Phase Timing Plan Comparison: Krome Avenue and Okeechobee Road |
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|
QEM Results
(Sub-problem 5a) |
Full Operational
Analysis |
|
QEM
Timing |
Equal v/c
Timing |
Equal Delay
Timing |
|
Yellow + All Red
Time per Phase (sec) |
4 |
4 |
6 |
6 |
|
Green Time (sec): |
|
WBLT |
10.8 |
10.8 |
9.7 |
17.7 |
|
EB & WB Through |
86.2 |
86.2 |
81.8 |
68.0 |
|
NB Through |
11.0 |
11.0 |
10.5 |
16.3 |
|
v/c ratio |
|
WBLT |
|
0.75 |
0.84 |
0.46 |
|
EB Through |
|
0.79 |
0.83 |
1.0 |
|
NB Through |
|
0.79 |
0.83 |
0.53 |
|
Critical v/c ratio |
0.82 |
0.79 |
0.83 |
0.83 |
|
Control Delay (sec/veh) |
|
WBLT |
|
81 |
96 |
52 |
|
EB Through |
|
14 |
18 |
47 |
|
NB Through |
|
71 |
76 |
52 |
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Overall
Intersection Delay |
|
20.4 |
24.5 |
42 |
|
Level of Service |
|
WBLT |
|
F |
F |
D |
|
EB Through |
|
B |
B |
D |
|
NB Through |
|
E |
E |
D |
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Overall
Intersection LOS |
|
C |
C |
D |
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Sub-Problem 5b
