ST0501-CS080829
MEMORANDUM
FROM THE
DEPARTMENT OF ENGINEERING
To: Ken Griffin, P.E., Director of Engineering and Public Works
From: DiWanna Baskins, Graduate Engineer
Date: August 29, 2008
RE: Request for Traffic Signal at the Intersection of Deforest Rd. and
MacArthur Blvd.
This traffic study is in response to requests from citizens in subdivisions adjacent to Deforest
Rd., inquiring if a signal could be installed to enhance the intersection due to the widening of
Deforest Rd. The Texas Manual on Uniform Traffic Control Devices is used to decipher if the
intersection warrants a traffic signal based off the traffic study conducted on March 27, 2008.
Refer to Section 4C.01, Studies and Factors for Justifying Control Signals for this study.
Warrant 1, Eight –Hour Vehicular Volume
Standard: The need for a traffic control signal shall be considered if an engineering study finds
that one of the following conditions exist for each 8 hours of an average day:
A.The vehicles per hour given in both of the 100 percent columns of Condition A in
Table 4C-1 exist on the major-street and the higher- volume minor- street approaches,
respectively, to the intersection;
This intersection does not meet this requirement.
OR
B.The vehicles per hour given in both of the 100 percent columns of Condition B in
Table 4C-1 existing on the major-street and the higher- volume minor-street
approaches respectively, to the intersection.
This intersection meets this requirement.
Standard: The need for a traffic control signal shall be considered if an engineering study finds
that both of the following conditions exist for each 8 hours of an average day:
A.The vehicles per hour given in both of the 80 percent columns of Condition A in
Table 4C-1 exist on the major-street and the higher-volume minor-street approaches,
respectively, to the intersection;
This intersection does not meet this requirement.
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AND
B.The vehicles per hour given in both of the 80 percent columns of Condition B in
Table 4c-1 exist on the major-street and higher-volume minor-street approaches,
respectively, to the intersection.
This intersection does not meet this requirement.
Warrant 2, Four –Hour Vehicular Volume
Standard: The need for a traffic control signal shall be considered if an engineering study finds
that, for each of any 4 hours of an average day, the plotted points representing the vehicles per
hour on the major street (total of both approaches) and the corresponding vehicles per hour on
the higher-volume minor-street approach (one direction only) all fall above the applicable curve
in Figure 4C-1 for the existing combination of approach lanes. On the minor-street, the higher
volume shall not be required to be on the same approach during each of these 4 hours.
This intersection meets this requirement.
Warrant 3, Peak Hour
Standard: This signal warrant shall be applied only in unusual cases. Such cases include, but are
not limited to, office complexes, manufacturing plants, industrial complexes, or high-occupancy
vehicle facilities that attract or discharge large numbers of vehicles over a short time.
This intersection does not meet this requirement.
The need for a traffic control signal shall be considered if an engineering study finds that the
criteria in either of the following two categories are met:
A.If all three of the following conditions exist for the same 1 hour (any four consecutive 15
minute periods) of an average day:
1.The total stopped time delay experience by the traffic on one minor-street
approach (one direction only) controlled by a STOP sign equals or exceeds: 4
vehicle-hours for a one-lane approach; or 5 vehicles-hours for a two lane
approach,
AND
2.The volume on the same minor-street approach (one direction only) equals or
exceeds 100 vehicles per hour for one moving lane of traffic or 150 vehicles per
hour for two moving lanes,
AND
3.The total entering volume serviced during the hour equals or exceeds 650 vehicles
per hour for intersections with three approaches or 800 vehicles per hour for
intersection with four or more approaches.
B.The plotted point representing the vehicles per hour on the major street(total of both
approaches) and the corresponding vehicles per hour on the higher-volume minor-street
approach (one direction only) for 1 hour (any four consecutive 15 minute periods) of any
average day falls above the applicable curve in Figure 4C-3 for the existing combination
of approach lanes.
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Warrant 4, Pedestrian Volume
Standard: The need for a traffic control signal at an intersection or midblock crossing shall be
considered if an engineering study finds that both of the following criteria are met:
A.The pedestrian volume crossing the major street at an intersection or midblock location
during and average day is 100 or more for each of any 4 hours or 190 or more during any
1 hour;
This intersection does not meet this requirement.
AND
B.There are fewer than 60 gaps per hour in the traffic stream of adequate length to allow
pedestrians to cross during the same period when the pedestrian volume criterion is
satisfied. Where there is an divided street having a median of sufficient width for
pedestrians to wait, the requirement applies separately to each direction of vehicular
traffic.
This intersection does not meet this requirement.
Warrant 5, School Crossing
Standard: The need for a traffic control signal shall be considered when an engineering study of
the frequency and adequacy of gaps in the vehicular traffic stream as related to the number and
size of groups of school children at an established school crossing across the major street shows
that the number of adequate gaps in the traffic stream during the period (see Section 7A.03) and
there are a minimum of 20 students during the highest crossing hour.
Before a decision is made to install a traffic control signal, consideration shall be given to the
implementation of other remedial measures, such as warning signs and flashers, school speed
zones, school crossing guards, or a grade-separated crossing.
The School Crossing signal warrant shall not be applied at locations where the distance to the
nearest traffic control signal along the major street is less than 300 ft., unless the proposed traffic
control signal will not restrict the progressive movement of traffic.
This intersection does not meet this requirement.
Warrant 6, Coordinated Signal System
Standard: The need for a traffic control signal shall be considered if an engineering study finds
that one of the following criteria is met:
A.On a one-way street or a street that has traffic predominantly in one direction; the
adjacent traffic control signals are so far apart that they do not provide the necessary
degree of vehicular platooning.
This intersection does not meet this requirement.
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B.On a two-way street, adjacent traffic control signal do not provide the necessary degree
of platooning and proposed and adjacent traffic control signal will collectively provide a
progressive operation.
This intersection does not meet this requirement.
Warrant 7, Crash Experience
Standard: the need for a traffic control signal shall be considered if an engineering study finds
that all of the following criteria are met:
A.Adequate trial of alternatives with satisfactory observance and enforcement has failed to
reduce the crash frequency; and
This intersection does not meet this requirement.
AND
B.Five or more reported crashes, of types susceptible to correction by a traffic control
signal, have occurred within a 12- month period, each crash involving personal injury or
property damage apparently exceeding the applicable requirement for a reportable crash;
and
This intersection does not meet this requirement.
AND
C.For each of any 8 hours of an average day, the vehicles per hour (vph) given in both of
the 80 percent columns of Condition A in table 4C-1 (see Section 4C.02), or the vph in
both of the 80 percent columns of Condition B in Table 4C-1 exists on the major-street
and the higher- volume minor-street approach, respectively, to the intersection, or the
volume of pedestrian traffic is not less than 80 percent of the requirements specified in
the Pedestrian Volume warrant. These major-street and minor-street volumes shall be for
the same 8 hours. On the minor street, the higher volumes shall not be required to be on
the same approach during each of the 8 hours.
This intersection does not meet this requirement.
Warrant 8, Roadway Network
Standard: The need for a traffic control signal shall be considered if an engineering study finds
that the common intersection of two or more major routes meets one or both of the following
criteria:
A.The intersection has a total existing, or immediately projected, entering volume of at least
1,000 vehicles per hour during the peak hour of a typical weekday and has 5- year
projected traffic volumes, based on an engineering study, that meet one or more of
Warrants 1, 2, and 3 during an average weekday; or
This intersection does not meet this requirement.
OR
B. The intersection has a total existing or immediately projected entering volume of at least
1,000 vehicles per hour for each of any 5 hours of a non-normal business day (Saturday or
Sunday).
This intersection does not meet this requirement.
A major route as used in this signal warrant shall have one or more of the following
characteristics:
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A.It is part of the street or highway system that serves as the principal roadway network for
through traffic flow;
This intersection does meet this requirement.
OR
B.It includes rural or suburban highways outside, entering, or traversing a City; or
This intersection does not meet this requirement.
OR
C.It appears as a major route on an official plan, such as a major street plan in an urban area
traffic and transportation study.
This intersection does meet this requirement.
Recommendation/Comments
According to Section 4C.01 of the TMUTCD manual, the intersection of Deforest Road and
MacArthur Blvd satisfies two of the warrants for justifying control signals. The intersection of
Deforest Road and MacArthur is unique because it is located approximately 750 ft. north of the
signalized intersection of Samuel Blvd. and MacArthur Blvd. Although, the intersection at
Samuel Blvd. can be timed to coordinate with the Deforest Rd. and MacArthur intersection, it is
not recommended to space signalized intersections less than 1000 ft. Taking into consideration
the directional flow of traffic during peak hours, recommended cycle length time, and the fact
that approximately 37 vehicles can be stacked in-between the signalized intersections may not
create ideal conditions during peak hours because turns onto MacArthur may create a
“bottleneck” effect. However, the nearest signalized intersection south of Samuel Blvd. and
MacArthur Blvd. is Parkway Blvd and MacArthur Blvd. Appropriate signal timing may
eliminate a bottleneck effect if vehicles proceeding onto MacArthur during peak hours are
allowed through the intersection of Samuel and MacArthur by coordinating both signals,
provided that stacking does not exceed occupancy in-between the next signalized intersection.
In the event that a traffic signal is installed, the intersection of Deforest Road and MacArthur
should be closely monitored so that the timing of the traffic signals will allow vehicles to
progress smoothly.
"CITY OF COPPELL ENGINEERING - EXCELLENCE BY DESIGN"