PZ Item 10 - Queueing Memo
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TEXAS
FORT WORTH
DENTON
ALLEN
SAN ANTONIO
CYPRESS
SUGAR LAND
GEORGIA
BLAIRSVILLE
ALBANY
TEXAS
FORT WORTH
DENTON
ALLEN
SAN ANTONIO
CYPRESS
SUGAR LAND
GEORGIA
BLAIRSVILLE
ALBANY
Memorandum
To: City of Southlake, Stephanie Taylor, P.E. – Transportation Manger
From: Chris Edwards, P.E.
CC: Philip Varughese, P.E.
Date: April 8, 2020
RE: Keller ISD Queueing Analysis: Florence Elementary
School Replacement
Teague Nall & Perkins, Inc. has performed a queuing analysis to evaluate the on-site storage
demands for the proposed Florence Elementary School Replacement in Keller Independent School
District (KISD). Florence Elementary is located at the intersection of Johnson Road and Harrell Drive
in Southlake, Texas. The site location and site plan are shown in Figure 1 and Figure 2, respectively.
Figure 1: Florence Elementary School Site Location
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Florence Elementary School Replacement is planned to open in August 2021, with an initial
population of 472 students served by approximately 40 faculty and staff. In August 2031 (10
years after opening), the school is expected to reach an ultimate capacity of 572 students. The
parking areas are divided into two separate areas to accommodate faculty and staff parking,
parent drop-off/pick-up, and bus loading zones. The available parent pickup drive is
approximately 1,065 linear feet (LF) from entrance to the furthest pick-up location. The bus drive
is expected to be approximately 725 LF. In addition, the site provides 169 on-site parking spaces,
of which 8 are accessible parking spaces.
Figure 2: Proposed Florence Elementary School Replacement Site Plan
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I. DATA COLLECTION
Trip generation data is based on information provided in the Trip Generation Manual, 10th Edition,
2017 and the Trip Generation Handbook, 3rd Edition, 2014, developed by the Institute of
Transportation Engineers (ITE). The average Weekday, PM Peak Hour of Generator trip rate for
Elementary Schools (ITE Land Use 520) is 0.34 trip generations per student (see Appendix A).
The traffic characteristics assumed for this analysis are as follows:
• The afternoon pickup will have a longer queue than the morning drop-off. Morning drop-off
activity is more temporally distributed and queue occupancy times are significantly lower.
For afternoon pickup, many vehicles arrive prior to release time and must wait in queue
until students are dismissed. Therefore, the afternoon pickup is considered more important
for calculating on-site storage queue lengths;
• The PM Peak Hour of Generator coincides with the KISD dismissal time for elementary
schools, currently 3:10 PM.
• From previous data collection, 67% of vehicular trips will queue before student dismissal,
and 33% will arrive after dismissal;
• The students will board the buses in the bus loading zone, precluding buses from using queue
storage in the student pick-up lanes;
The number of PM peak trips generated by the proposed Florence Elementary School Replacement
in the opening year of 2021, and the ultimate design year of 2031, are computed in Table 1.
Table 1: Expected Florence Elementary School Replacement Personal Vehicle Volumes
II. QUEUE LENGTH ANALYSIS
To accommodate queue length, the proposed elementary site has the following characteristics. The
proposed parent loop for student pick-up/drop-off is designed to be 24’ wide to accommodate
two lanes of queuing, resulting in 2,130 LF of storage.
A total of 169 parking spaces are provided on site and the school employs approximately 40
faculty and staff members. Assuming each faculty and staff member drives separately to work, 121
spaces remain available for parent parking (does not include accessible parking), which may further
reduce the expected queue by 2,420 LF (assuming 20’ per car).
To estimate queue lengths generated prior to school release, the following assumptions were made:
• Each vehicle occupies 20 feet of queue length;
• 67% of the projected vehicles are expected to arrive at the school prior to student release;
• There are 169 parking spaces planned on the campus, of which 8 are accessible spaces.
A total of 121 spaces are available after allowing for faculty/staff and leaving accessible
spaces open.
Year:2021 2031
Total Number of Students: 472 572
Total PM Peak Trips Generated (0.34 trips/student):160 194
Percentage of Trips Queueing before dismissal: 0.67 0.67
Personal Vehicles expected in Peak Queue: 108 130
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Using these assumptions, the estimated storage length needed to accommodate the expected total
queue length before the school release time is approximately 2,160 LF, based on 108 vehicles in
2021. The storage length needed in 2031 is approximately 2,600 LF, based on 130 vehicles. The
following table contains the calculated and provided length of queuing space as designed on the
site plan for the initial student population in 2021 and with full build-out conditions and enrollment
in 2031.
Table 2: Calculated and Provided Queue Storage
Figure 3 shows the proposed Florence Elementary School Replacement and some of the surrounding
roadway network. The figure shows that the calculated pick-up queue (2,160 LF in Year 2021 and
2,600 LF in Year 2031) can be accommodated within the proposed elementary school site if a
portion of the available parking is utilized.
2021 472 108 2,160 2,130 2,420 4,550
2031 572 130 2,600 2,130 2,420 4,550
Year No. of
Students
No. of Personal
Vehicles
expected in
Queue
Linear Feet of Queue Storage
Storage
Needed
Queue Lane
Storage
Parking
Storage Total Storage
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Figure 3: Proposed Florence Elementary School Replacement Pickup Queue
III. CONCLUSIONS AND RECOMMENDATIONS
The queueing study for the proposed Florence Elementary School Replacement in KISD is
provided to determine the expected storage requirements for afternoon pickup based on the
peak vehicle queue typically occurring during dismissal. This study is based on expected
characteristics of the proposed school, characteristics of nearby schools, and information
provided in the Trip Generation Manual, 10th Edition, 2017 and the Trip Generation Handbook,
3rd Edition, 2014, developed by the Institute of Transportation Engineers (ITE).
The queuing analysis shows that all queued vehicles will be maintained within the school property
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during the peak periods and not impede the flow of traffic on adjacent streets. The parent loops
are designed to minimize or eliminate any crossing of traffic flows within the queuing area. In
addition to the parent loops, there are 121 open parking spaces available to accommodate an
additional 2,420 LF of queue.
Based on best planning practices, the following strategies to minimize peak queuing conditions
on school campuses can be considered:
• Create safe routes for pedestrians and bicyclists to encourage use of these modes instead
of trips by vehicle. School administration can also actively promote walking or biking to
school among students.
• Utilize the 121 standard parking spaces expected to be available for parents that arrive
early. To ensure parents use these spaces instead of the joining the queue, it is suggested
that they receive direction to use these parking spaces.
• Enforce “No Parking” along the circulation path during drop-off and pick-up operations.
• Student pick-up area is inside the school campus and not along the street.
• No unattended vehicles should be in the queue line. Parking spaces are provided if parents
need to leave their vehicles.
• Staff and/or volunteers should assist in loading students.
• It is recommended that a school representative stand near the entrance to the parent pick-
up driveway and, if the drives are full, direct traffic to use the available parking spaces
for queueing purposes.
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Appendix A
ITE Trip Generation for Elementary Schools
(Land Use 520)
PM Peak Hour of Generator