Problem 5: Signalization of
Okeechobee Road
Printable Version
The
Manual of Uniform Traffic Control Devices (MUTCD) is the
primary resource for determining whether a traffic signal
is the appropriate application for a particular location. The MUTCD has a
series of signal warrants that evaluate various aspects of an intersection
to provide the engineer with guidelines for consideration in making this
decision.
An HCM analysis of an unsignalized intersection alone is not
enough to justify that a traffic signal is warranted at a particular
location. In the case of this particular intersection, the engineering study
considered the primary function of Okeechobee Road, adjacent facilities that
could be considered, and the feasibility of a higher type interchange in
concert with the operations of the Krome Avenue northbound movement.
That being said, we have estimated
that a TWSC will result in significant delay to the northbound leftturn
movement onto Okeechobee Road from Krome Avenue, and a
traffic signal should be considered as a potential control alternative to accommodate the projected traffic
volumes.
Problem 5 will explore various aspects of the HCM treatment of signalization
as it applies to this intersection.
Procedures are provided in
HCM Chapter 16 for the analysis of signalized intersections. The procedures may be applied to each
lane group to produce
separate
control delay estimates. The lane group values may then be combined
in a volumeweighted manner to produce aggregate estimates for each approach
and for the intersection as a whole.
Subproblem 5a.
Twophase Traffic Signal Control
Subproblem 5b. Threephase Traffic Signal Control, adding
a protected left turn
Subproblem 5c.
Pretimed vs.
TrafficActuated Operation [ Back ]
to Problem 4 [ Continue ] with
Problem 5 
Page Break
Problem 5:
Signalization of Okeechobee Road
The HCM suggests in
Chapter 16 that freeflowing right turns that are not under signal
control should be removed entirely from the analysis. We have already
established that the northbound and eastbound right turns are free flowing
because of channelization. Therefore, neither of these movements will be
considered as a part of the signalization.
The current TWSC operation
at this intersection provides only one lane for the northbound left turn (see
photo).
Because of the available space and the capacity advantage of a second lane
under signal control, two lanes will be assigned to this movement. In
addition, because of the geometrics of this T intersection, the northbound
left turn has more of the characteristics of a through movement than a left
turn. Therefore, for purposes of signal analysis, the northbound left turn
will be considered as a through movement.
The signal analysis
subproblems will be based on the following demand volumes:
Exhibit 335. Peak Hour
Volumes: Krome Avenue at Okeechobee Road
For Signal
Analysis 
Approach 
Left 
Through 
Right 
Northbound 
 
257 
 
Southbound 
 
 
 
Eastbound 
 
2,010 
 
Westbound 
120 
358 
 
Discussion:
Consider
the following issue as you proceed through this problem: what
criteria is necessary to define right turns as freeflowing right turns?
Take a few minutes to consider this question. When you are ready to
continue, click continue below to proceed. [
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Problem 5 [ Continue ] to
Subproblem 5a 
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Subproblem 5a: TwoPhase
Traffic Signal Control
Step 1. Setup
A twophase control plan
provides no protected phases for any of the left turns that are opposed by
through traffic. The westbound approach has the only leftturn movement in
this category. With a volume of 120 vph, it is conceivable that this
movement could be accommodated without a protected phase.
Some agencies would decide
to provide a protected leftturn phase for this movement, without further
analysis, because of the high speed (50 mph) of the approaching traffic.
This is a legitimate issue. The
twophase alternative is therefore presented in this subproblem primarily
as an illustration of the details of the HCM procedures. For some agencies,
the outcome of this analysis will be a moot point with respect to the decision itself.
We will examine the
twophase alternative using both the Quick Estimation Method (QEM) presented
in HCM Chapter 10 and the full operational analysis procedure presented in
HCM Chapter 16.
Consider the following as you proceed through this
problem:

The Quick Estimation Method (QEM) uses the critical
movement technique (also known as the critical movement analysis) to
estimate the intersection capacity. At a conceptual level, how would you
use the critical movement technique to estimate the capacity of an
intersection? 
 The QEM is similar to the critical movement analysis in
that they are both planning level analyses. What factors will cause
variation between the QEM and the full operational analysis? 
Discussion:
Take
a few minutes to consider these questions. Click continue when you are
ready to proceed. [ Back ] [ Continue ] with
SubProblem 5a 
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Subproblem 5a:
TwoPhase Traffic Signal Control
Step 2: Results
The QEM represents an
extension of a technique known as Critical Movement Analysis, or CMA. This
technique has appeared in the literature in several forms and is intended
primarily for planning level analysis, though it is also very useful in both
operational and design reviews. The QEM produces an estimate of the
status of the overall intersection with respect to its capacity, based on
the assumption that the signal timing plan will produce an equal degree of
saturation among the critical movements on each phase. The intersection
status is determined from the sum of the v/c ratios for the critical
movements on each phase.
The QEM produces, as a by
product, a synthesized signal operating plan consisting of:

A
phasing plan determined by the left turn treatments for each approach. The
leftturn treatments may be specified, or they may be synthesized, based
on the volumes of the leftturn movement and its opposing through
movement. 

A cycle
length that will produce a target
v/c ratio of 90%. 

An allocation
of phase times that will equalize the degree of saturation among the
critical movements on each phase. 
The HCM offers the caveat
that the synthesized plan may not be suitable for implementation because it
does not include important considerations such as minimum green times.
Nevertheless, it usually provides a good starting point for an operational
analysis, which requires the signal timing plan to be specified along with
several other items of geometric, operational, and traffic data that are not
always available at the planning level.
[
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Subproblem 5a:
TwoPhase Traffic Signal Control
Both the QEM and the
operational analysis procedure have the same underlying logic. In many
places, the QEM
uses assumed or default values and the operational analysis
procedure uses more precise sitespecific data. Therefore, some differences
can be expected in the results, and those differences are generally
attributable to the approximate nature of the QEM.
The QEM provides two
checks to evaluate the need for a protected left turn on each approach. The
first involves computing the product of the volumes for the left turn and
its opposing through movement. The cross product criterion has been
described in the literature as a popular technique that generally preceded
the availability of more complex computational models. Different cross
product thresholds have been adopted by different agencies, and the threshold
values are generally dependent on the number of available lanes. Thresholds
of 50,000, 90,000 and 110,000 are typically recommended for 1,2 and 3,
through lanes respectively.
[
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Subproblem
5a: TwoPhase Traffic Signal Control
The application of the QEM
cross product check to this subproblem is summarized as follows:
Exhibit 336. QEM
data summary 
Left turn volume 
120 vph 
Opposing thru volume 
2,010 vph 
Cross product 
241,200 
QEM
threshold for two lanes of opposing traffic 
90,000 
So, the QEM cross product
check suggests the need for a protected left turn.
The second leftturn
protection check in the QEM involves the determination of sneaker capacity,
i.e., the number of left turns that can be accommodated assuming that two
vehicles proceed at the end of each permitted phase. Sneakers are
considered to create extra capacity for a leftturn movement. The HCM
suggests that most of the capacity for permitted left turns will be
generated by sneakers whenever the through vehicle equivalence of a left
turn exceeds 3.5. HCM Exhibit C163 provides a table that expresses the leftturn
equivatents as a function of the opposing flow and the type of left
turn lane (shared or exclusive). The QEM prescribes a check for sneaker
capacity when the leftturn equivatents suggest that most of the capacity
will be associated with sneakers.
[
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Subproblem 5a:
TwoPhase Traffic Signal Control
The application of the QEM
sneaker check to this subproblem is summarized as follows:
Exhibit 337. QEM Results Summary 
Left turn volume 
120 vph 
Left turn equivalence 
9.6 (i.e., > 3.5) 
Cycle length 
120 sec 
Cycles per hour (3,600/120) 
30 
Capacity at 2 veh/cycle 
60 
So, the QEM sneaker check
also suggests the need for a protected left turn, because the leftturn
demand (120 vph) is greater than the apparent sneaker capacity (60 vph).
The operational procedure
presented in HCM Chapter 16 offers the perspective of delay and v/c ratio for the leftturn movement.
These more detailed performance measures are beyond the scope of the QEM.
Applying the operational procedure using the twophase signal timing plan given by the QEM, we see the following results for the WB left turn:
Exhibit 338. Operational Procedure Results Summary 
v/c ratio 
1.02 
Control Delay per Vehicle 
98 sec 
Level of Service 
F 
These results confirm from
three different perspectives that a signal operation is unlikely to
accommodate the westbound left turn satisfactorily without a protected
phase. The next subproblem will examine a threephase operation with
protection for this movement.
[
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Subproblem 5b:
ThreePhase Traffic Signal
Control with a Protected Westbound Left Turn
Step 1. Setup
Having established
the need for westbound leftturn protection in Subproblem 5a, we will now
examine the HCM treatment of protected left turns. Because of the isolated
and high speed characteristics of this intersection, we would expect to
implement a control scheme in which all movements are trafficactuated. We
will, however, limit the investigation to pretimed control in this
subproblem, leaving trafficactuated control for Subproblem 5c. There are
two reasons to separate the control treatment into different subproblems.
First, we can get a better idea of how these control modes differ if we
examine both of them in detail. Second, the timing plan based on pretimed
control is often a useful input into the analysis of trafficactuated
operation.
Consider:

During this subproblem, signal timing strategies are
explored. There are three different schools of thought on the issue: one
thought is to equalize the v/c ratio for each approach, another is to
equalize the delay, and the last is to minimize delay. What pros and cons
do you think are associated with each of these strategies? Considering
roadway volumes, lane groupings, and other issues that may affect each of
the parameters, do you think one solution will always be desirable? 
 After you have read through this subproblem, reflect
on the first question and see if your initial thoughts still hold true. 
Discussion:
Take
a few minutes to consider these questions. Click continue when you are
ready to proceed. [
Back ] to SubProblem 5a [
Continue ] with SubProblem 5b 
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Subproblem 5b:
ThreePhase
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.

Equalizing the delay among the critical
movements on each phase.

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 339.
Exhibit 339. ThreePhase Timing Plan Comparison: Krome Avenue and Okeechobee Road 

QEM Results
(Subproblem 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 
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 
Overall
Intersection LOS 

C 
C 
D 
[
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SubProblem 5b 
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Subproblem 5b:
Threephase
Traffic Signal Control with a Protected Westbound Left Turn
The Equal v/c
Strategy
The equal v/c strategy
was explored to some extent in the last subproblem as the basis for the QEM
timing plan synthesis. The QEM results are repeated in one column of Exhibit
339. The next column shows what happens when the QEM timing plan is
transferred directly into the operational procedure. The following
observations are offered:

The critical phase v/c ratios computed
by the operational procedure are nearly, but not quite, equal (0.75 vs.
0.79). In other words, the more detailed treatment of saturation flow
rate, lost time, etc., by the operational procedure has produced minor
differences in the results. 

Additional performance measures are
provided by the operational procedure, including v/c ratios delays and
level of service for each lane group. The QEM does not carry its
computations to this level. 
The default yellow
plus all red time for the QEM is 4 seconds per cycle per phase. The
unusually wide intersection and high speed approaches dictates a longer
intergreen period. For purposes of this discussion, values of 5 sec yellow
and 1 sec all red will be used as an approximation of the local agency
practice. While a 4second intergreen is generally a reasonable default
value for planning level analysis, this is a case in which the QEM
assumptions do not apply to the intersection in question.
[
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SubProblem 5b 
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Subproblem 5b:
Threephase
Traffic Signal Control with a Protected Westbound Left Turn
This analysis was repeated
with two modifications. First, the intergreen times were increased from 4
sec to 6 sec. Second, the green times were redistributed by trial and error
to produce a closer agreement between the v/c ratios for the critical
movements. The results are shown in the next column of
Exhibit 339. The
following observations are offered:

The critical v/c ratio for the whole
intersection was increased from 0.79 to 0.83 as a result of increasing the
intergreen times and thereby reducing the effective green times.


The increase in v/c ratios was,
predictably, accompanied by an increase in delay; but the delay increase
was not sufficient to change the level of service for any of the
movements. 

The critical v/c ratios for each phase
are in closer agreement (0.83, 0.83 and 0.84). This was the closest
possible agreement that could be produced by trial and error with 0.1 sec
resolution in the green times. 

The control delays and levels of
service differ widely among the various movements. This observation makes
it clear that equalizing the v/c ratios does not necessarily equalize the
delays among competing movements. Note that the delays varied from 18 sec
per vehicle to 96 sec per vehicle and the LOS varied from B to F. 
[
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SubProblem 5b 
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Subproblem 5b:
Threephase
Traffic Signal Control with a Protected Westbound Left Turn
The Equal Delay Strategy
The equal delay
strategy was implemented by redistributing the green times, again
by trial and error, to produce a closer agreement between the delays for the
critical movements. The results are shown in the next column of
Exhibit 339.
The following observations are offered:

The signal timing for this strategy is
noticeably different than the corresponding timing for equalizing the v/c
ratios. 

The previously equal v/c ratios for the
competing movements now vary from 0.49 to 1.0 as a result of
redistributing the green times. 

The critical v/c ratio for the whole
intersection has not changed from its previous value of 0.83. The critical
v/c ratio is not affected by the distribution of green times. The
computations for this performance measure are always based on the
assumption of equal v/c ratios. This is an important point. The critical
v/c ratio is a measure of overall intersection sufficiency and does not
reflect the actual distribution of green times. 

The control delays are now in much
closer agreement among the competing movements. The EB through movement
still has a slightly lower delay (47 sec per vehicle vs. 52 sec per
vehicle for the other two movements). Note that the v/c for this movement
is 1.0. To fully equalize the delays for all movements, the EB through
movement would have to be forced to operate beyond its capacity. It is
common signal timing practice to halt the iterative distribution of green
times when further redistribution would create an oversaturated movement.


In spite of the slight difference
in the
control delay values, LOS D now applies to all of the competing movements
and to the overall intersection. 
[
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SubProblem 5b 
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Subproblem 5b:
Threephase
Traffic Signal Control with a Protected Westbound Left Turn
These observations
reinforce the notion that, in the search for an equitable distribution of
green times, there is a tradeoff between equalizing the v/c ratios and
equalizing the delays. The question of which strategy is preferable raises
an interesting philosophical question. Note that equalizing the delays has
reduced the overall intersection LOS from C to D. So a reporting scheme that
considers only the overall LOS would tend to favor the equal v/c strategy.
On the other hand, the improvement in overall intersection LOS was achieved
at the expense of the lower volume movements that were forced to operate at
LOS E and F. So, a reporting scheme that is concerned with individual
movements might look more favorably on equalizing the delay.
This debate might spawn a
third strategy, namely that of equalizing the LOS among the competing
movements without worrying too much about differences in delay. The results
would be expected to fall somewhere between the two strategies that we have
explored.
Now here is a question to
ponder: why is the overall intersection delay of 42 sec per vehicle lower
than the delays for any of the movements shown in
Exhibit 339? The answer is
that our analysis has focused on the critical movements and has neglected
other movements such as the WB through traffic, which was not involved in
any of the computations for the signal timing strategies we explored.
The procedure prescribed by the HCM for estimating overall intersection LOS
takes all movements into account, not just the critical movements.
[
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SubProblem 5b 
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Subproblem 5b:
Threephase
Traffic Signal Control with a Protected Westbound Left Turn
The Minimum Delay Strategy
The final strategy
mentioned in the HCM is that of minimizing the sum of the delays to all
vehicles entering the intersection. This strategy seeks an optimal solution
instead of an equitable solution to the design of the signal timing plan.
The overall intersection delay shown in
Exhibit 339 was 24.5 sec/vehicle for
the equal v/c strategy, compared to 42 sec/vehicle for the equal delay
strategy. It is this performance measure that we seek to minimize.
The minimum delay strategy
also requires an iterative process that can be implemented either with
available software or by trial and error. It is common practice to start
this process using the equal v/c strategy as an initial solution. Following
this practice, it was found that the equal v/c solution could not be
improved upon by redistributing the green times. In other words, it was not
possible to lower the overall intersection delay below 24.5 sec/vehicle. So
we must conclude that the equal v/c solution in this case was also the
minimum delay solution.
While this outcome
should not be interpreted as a general signal timing principle, it will be
found that the outcomes of these two strategies are frequently not far apart
at isolated intersections, such as the one in question. Delay minimization is
a more important strategy in coordinated systems where other design
parameters related to the quality of progression between intersections must
be optimized.
[ Back ] [
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SubProblem 5c 
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Subproblem 5c: Pretimed vs.
TrafficActuated Operation
Step 1. Setup
In Subproblem 5b, we
explored various strategies for allocating green time with pretimed
control. Because of the isolated highspeed nature of this intersection, it
is important that trafficactuated control be used. In this subproblem, we will examine the HCM
treatment of trafficactuated control to see how it differs from pretimed
control.
Consider:

What are the primary operation effects of using
actuated control? 

What additional information is needed beyond the data
already used in Subproblem 5b? 

How can actuated control improve the efficiency of a
signalized intersection? 
 How can actuated control improve the safety of a
signalized intersection? 
Discussion:
Take
a few minutes to consider these questions. Click continue when you are
ready to proceed. [ Back ] to SubProblem 5b [
Continue ] with SubProblem 5c 
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Subproblem 5c:
Pretimed vs. TrafficActuated Operation
The signal timing
specification for trafficactuated control has the same format on the HCM
worksheets as pretimed control. The phasing plan is required in both cases,
along with the allocation of green times. In the case of pretimed control,
the green times are expected to be the actual green time settings for the
controller. In the case of trafficactuated control, the actual green times
will vary from cycle to cycle. The values expected by the HCM procedure are
the average green times that will be generated over the analysis period by
the controller logic. Appendix B to HCM Chapter 16 gives guidelines for
determining average green times.
What are the primary operation effects of using actuated
control?
The input data associated
with trafficactuated control (e.g., lower cycle lengths) will often produce
lower delay estimates than those associated with pretimed control. There is
only one difference in the analytical treatment of pretimed and
trafficactuated control at isolated intersections. That difference is found
in the k parameter of the incremental delay equation. HCM Exhibit 163
gives a table of k values that account for trafficactuated control as a
function of the
unit extension and the
v/c ratio.
What additional information is needed beyond the data
already used in Subproblem 5b?
Because the v/c ratio is
already computed for pretimed control, the only additional piece of
information you need to apply the procedure to trafficactuated control is
the unit extension time setting. This setting represents the duration of the
gap between vehicles on the approach being serviced that will cause the
controller to terminate the phase. Smaller unit extensions will produce
smaller k values, and smaller k values will produce lower delay estimates.
For purposes of this discussion, we will adopt the default setting of 3.0
seconds given in HCM Chapter 10.
[
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Subproblem 5c:
Pretimed vs. TrafficActuated Operation
Step 2: Results
Three cases involving
different timing plans will be examined in this subproblem: The first will
use the optimal timings from Subproblem 5b. The difference in the results
will be due solely to differences in the HCM treatment of trafficactuated
control. The results are summarized in Exhibit 340.
Note that there
were no differences in the v/c ratio, g/c ratio, or uniform delay values in
the comparison of pretimed and trafficactuated operation. The k values
were all 0.5 for pretimed control and 0.37 for trafficactuated control.
The reduction in the k values produced a slight decrease in the incremental
delay for all movements, and this decrease was reflected in the control
delay. The overall intersection delay decreased by 1.5 seconds per vehicle, or about 6
percent.
Exhibit 340. Comparison of
Pretimed and Trafficactuated Control with the Same Timing Plan 

Pretimed
Subproblem 5b 
Actuated
Subproblem 5c 
Eastbound Through 


v/c 
0.83 
0.83 
g/c 
0.68 
0.68 
Uniform delay 
14.1 
14.1 
k value 
0.5 
0.37 
Incremental delay 
3.6 
2.7 
Control delay 
17.6 
16.7 
Westbound Left 


v/c 
0.84 
0.84 
g/c 
0.08 
0.08 
Uniform delay 
54.4 
54.4 
k value 
0.5 
.37 
Incremental delay 
41.7 
33.6 
Control delay 
96.1 
88.0 
Northbound
Through 


v/c 
0.83 
0.83 
g/c 
0.09 
0.09 
Uniform delay 
53.9 
53.9 
k value 
0.5 
0.37 
Incremental delay 
21.9 
16.9 
Control delay 
75.8 
70.8 
Overall
intersection delay 
24.5 

[
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Subproblem 5c:
Pretimed vs. TrafficActuated Operation
One of the purported
benefits of trafficactuated control is a more efficient timing plan.
Appendix B of HCM Chapter 16 provides a method for estimating the average
green times as a function of the traffic volumes, geometric configuration,
left turn treatments, and detector parameters. The methodology of this
appendix is iterative and somewhat complex analytically. It cannot be
applied productively without software designed for the purpose.
While all of the
controller and detector parameters can influence the cycle length and green
times for actuated control, the most important setting is the maximum green
time for each phase. The HCM suggests that it is clearly essential that
some maximum green times must be imposed to control the apportionment of
time between the competing phases.
A number of techniques for
assigning maximum green times have appeared in the literature. Most
techniques involve some adjustment to the optimal green times for pretimed
operation. Three different ways of using the pretimed optimal green times
to determine the actuated average green times will be examined in this
subproblem:
 Direct use of the optimal green
times as average green times, as discussed in the first example in this
subproblem.
 Application of the HCM appendix
with maximum green times set equal to the optimal green times.
 Application of the HCM appendix
with maximum green times set equal to 150 percent of the optimal green
times.
[
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Subproblem 5c:
Pretimed vs. TrafficActuated Operation
The results are presented
on the next page in
Exhibit 341. While there was a wide variation in the
resulting cycle length, there was very little difference observed in the
overall intersection delay. The shortest cycle, 109 sec, was obtained by
using the pretimed optimal greens as maximum greens. The longest cycle (140
sec) was obtained from 150 percent of the optimal greens.
So, what have we learned? In this example, the only way that trafficactuated control
could beat
optimized pretimed control in this table is by assuming that the actuated controller
would generate an optimal timing plan; consistent with the optimized
pretimed average green times. Of course, this is all predicated on the
completely unrealistic assumption that the approach traffic volumes will be identical
for each day and for every cycle. On the other hand, there is nothing
built into conventional actuated control logic that maintains average splits
at an intersection without tight control of the maximum green times.
How can actuated control improve the safety of a
signalized intersection? Someone might
question whether trafficactuated control at highspeed isolated
intersections should be applied because of the operations analysis. The
answer is an emphatic yes, because of the dilemma zone protection that is
possible with the proper placement of detection zones on each approach and
proper timing settings within the controller. Certainly, support for this
answer will not always come from an HCM analysis, but it is always important
to keep considerations such as this in mind when making implementation
decisions.
[
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Subproblem 5c:
Pretimed vs. TrafficActuated Operation
Exhibit 341.
Comparison of TrafficActuated Timing Plans 

Method of
Determining Average Green Times 
Optimal
Pretimed Values Used Directly as Average Green Times 
HCM Chapter 16
Appendix B with Max Greens Based on Pretimed Optimal Values Multiplied
by a Factor 
Factor = 1.0 
Factor = 1.5 
Green Time (sec): 



WBLT 
9.7 
10 
15.0 
EB & WB Through 
81.8 
70.5 
91.6 
NB Through 
10.5 
11 
16 
Cycle Length 
120 
109.5 
140.6 
v/c ratio 



WBLT 
0.84 
0.74 
0.63 
EB Through 
0.83 
0.88 
0.87 
NB Through 
0.83 
0.72 
0.64 
Critical v/c ratio 
0.83 
0.85 
0.81 
Control Delay
(sec/vehicle) 



WBLT 
88 
65 
67 
EB Through 
17 
20 
24 
NB Through 
71 
55 
63 
Overall
Intersection Delay 
23.0 
23.3 
26.6 
Level of Service 



WBLT 
F 
E 
E 
EB Through 
B 
C 
C 
NB Through 
E 
D 
E 
Overall
Intersection LOS 
C 
C 
C 
[ Back ] [
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