Section 6-1 Traffic Impact Analysis 2026.pdf
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CHAPTER 6: TRANSPORTATION
SECTION 1: TRAFFIC IMPACT
ANALYSIS
Engineering Design Standards
City of Buckeye, Arizona
January 2026
6-1 Traffic Impact Analysis
City of Buckeye
2026
Summary of 2026 Section 6-1 Updates
Section 6-1 is an extensive overhaul/update to the prior version of this section. Applicants
are encouraged to familiarize themselves with the document in its entirety.
6-1 Traffic Impact Analysis
City of Buckeye
2026
Table of Contents
6-1.000
General Information ........................................................................................... 2
6-1.001
Traffic Infrastructure Requirements...................................................................................... 2
6-1.002
Acronyms, Definitions, and Abbreviations ....................................................................... 2
6-1.003
Design Policy .......................................................................................................................................... 5
6-1.004
Diligence .................................................................................................................................................... 7
6-1.005
Private Streets ........................................................................................................................................ 7
6-1.006
Standards ................................................................................................................................................. 7
6-1.100
TIA Reports .......................................................................................................... 8
6-1.101
General Requirements ................................................................................................................... 8
6-1.102
Traffic Statement (TS) .................................................................................................................... 8
6-1.103
Traffic Impact Analysis / Report ............................................................................................. 10
6-1.200
Traffic Analysis Scenarios ............................................................................... 17
6-1.201
Updating an Existing TIA ............................................................................................................... 17
6-1.202
TIA Amendment / Update ........................................................................................................... 17
6-1.300
Analysis Criteria ................................................................................................ 18
6-1.301
Area of Influence ................................................................................................................................ 18
6-1.302
Study Horizon Years ......................................................................................................................... 18
6-1.303
Trip Generation Thresholds ........................................................................................................ 18
6-1.304
Trip Generation ................................................................................................................................... 18
6-1.305
Trip Distribution and Assignment .......................................................................................... 21
6-1.306
Capacity Analysis ............................................................................................................................. 21
6-1.307
Right Turn on Red Reduction .................................................................................................... 22
6-1.308
Traffic Counts ...................................................................................................................................... 22
6-1.309
Peak Traffic Hours ............................................................................................................................ 22
6-1.310
Seasonal Adjustments ................................................................................................................. 22
6-1.311
”K”-Factor ............................................................................................................................................... 23
6-1 Traffic Impact Analysis
City of Buckeye
2026
6-1.312
Data Collection Requirements ............................................................................................... 23
6-1.313
Traffic Signal Warrant Analysis ............................................................................................. 24
6-1.314
Traffic Impact Analysis Methodologies ........................................................................... 25
6-1.315
Mitigation Measures ...................................................................................................................... 25
6-1.316
Proposed Development - Mode Split ............................................................................... 25
6-1.317
Level-of-Service (LOS) Analysis ........................................................................................... 26
6-1.318
Turn Lane Storage Analysis ...................................................................................................... 26
6-1.319
Improvement Analysis ................................................................................................................ 28
6-1.320
Additional Criteria for School Sites ..................................................................................... 28
6-1.400
Traffic Analysis Software ................................................................................ 29
6-1.401
Trafficware – Synchro .................................................................................................................. 29
6-1.402
Trafficware – SimTraffic ............................................................................................................. 29
6-1.500
Master Traffic Impact Analysis for CMPs ...................................................... 31
6-1.501
General Information: ....................................................................................................................... 31
Table of Tables
Table 1 – Analysis Criteria ......................................................................................................................................... 20
Table 2 – Table of Recommendation .............................................................................................................. 30
Table of Figures
Figure 1 – TIA City Signature/Approval Block ................................................................................................ 10
Figure 2 - Graphical Representation of Improvements ..................................................................... 30
6-1 Traffic Impact Analysis
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6-1 – Traffic Impact Analysis
This section provides policy and standards establishing criteria for completing a Traffic
Impact Analysis (TIA). The requirements of this section are set by the City of Buckeye (City)
for all public and private streets. This standard provides guidance on the section and
requirements for Traffic Impact Analysis (TIA).
The City Engineer is required, pursuant to Chapter 23, Article 23-2, of the City Code, to develop
standards and details regarding improvements to be constructed within the city. The
standards, design criteria, and policy set forth in this section were developed and
recommended by the City Engineer pursuant to Chapter 23, Article 23-2, and adopted by the
City Council in Resolution No. 04-26 on 1/20/2026.
Implementation: The requirements of this section shall become effective in accordance with
City Code. The standards and requirements of this section shall apply to all new traffic
analyses, including traffic analyses seeking a new City Engineer’s signature or a re-approval
from the City Engineer, submitted to the City following the effective date of the City Council’s
adoption of the resolution approving the standards and requirements of this section.
Modification Authority: The City Engineer or designee may approve variances to the
requirements of this section. For deviations to Section 6-1 only, variances shall be established
by documented correspondence and concurrence with the City Engineer or designee. The
documentation or correspondence shall be included in an appendix to the Traffic Impact
Analysis.
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6-1 Traffic Impact Analysis
6-1.000 General Information
6-1.001 Traffic Infrastructure Requirements
A. It is the City’s responsibility to provide an interconnected transportation
system to ensure the mobility of people and goods.
B. Developers/Landowners shall construct, at their expense, all on-site/internal
and off-site/external transportation and parking infrastructure necessary to
serve their developments and to mitigate off-site traffic impacts that will
otherwise be caused by their development. Infrastructure shall be
determined in accordance with the results of a City-approved traffic analysis
or as otherwise required by the City.
C. The City will stipulate that certain items be the responsibility of the Developer
as a condition of development approval. Such items may include additional
right of way (ROW) dedication or acquisition, street improvements, traffic
signals and/or transportation demand management measures deemed
necessary to mitigate transportation deficiencies as identified by the TIA.
6-1.002 Acronyms, Definitions, and Abbreviations
•
AASHTO - The American Association of State Highway and Transportation
Officials
•
Approach Taper - A lateral shift of a through traffic lane in order to add a new
lane, such as for the addition of a left turn lane at the approach to an
intersection.
•
Area of Influence - The geographic area surrounding the site from which the
development is likely to draw a high percentage (80% or more) of the total
site traffic.
•
Area of Significant Traffic Impact - The geographic area which includes the
facilities significantly impacted by the site traffic.
•
A.R.S. - Arizona Revised Statutes
•
Buildout year - The year that the entire development is intended to be
completely constructed and operational.
•
Capacity - The maximum volume of vehicles that a lane or roadway can
accommodate while efficiently moving traffic (level of service D or better).
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Capacity is usually expressed as vehicles per hour (vph), passenger cars per
hour (pcph), persons per hour (pph), or average daily vehicles per day (ADT)
•
City - City of Buckeye
•
City Engineer - The City of Buckeye City Engineer or designee.
•
City Traffic Engineer – The City of Buckeye City Traffic Engineer or designee.
•
Clustered Signals – Traffic signals that are closely spaced or spaced at
regular intervals such that capacity and LOS are interrelated.
•
CMP - Community Master Plan
•
COB - City of Buckeye
•
Developer - Shall mean the individual or entity proposing Development of
land in the City, including Development companies authorized to act on
behalf of the Developer and the term Developer shall also mean a contractor
(“Contractor”) authorized to act on behalf of the Landowner or Developer.
Developer shall also be interpreted to mean Landowner.
•
Development - Shall have the same meaning as defined in the City
Development Code.
•
DHV – Design hourly volume.
•
Engineer - An engineer registered professionally in the State of Arizona
pursuant to the provisions of A.R.S. §32-101; §§32-121-131; §§32-141-152, as
amended.
•
HCM - Highway Capacity Manual, latest edition
•
ICU - Intersection Capacity Utilization. A planning method for measuring a
roadway intersection’s capacity.
•
Internal Capture – A trip that begins and ends within the same development,
thus not causing trips external to the development. This can occur when
developments include multiple land uses.
•
ITE - Institute of Transportation Engineers
•
Landowner - Shall mean the owner of the land in the City on which
Development occurs. “Landowner” shall also be interpreted to mean
Contractor and/or Developer, including Development companies authorized
to act on behalf of the Developer/Landowner.
•
LOS - Level of service - A qualitative measure describing operational
conditions within a traffic stream, based on service measures such as speed,
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travel time, freedom to maneuver, traffic interruptions, comfort, and
convenience. Six levels of service are defined for each type of facility that has
analysis procedures available. Letters designate each level, from A to F, with
LOS A representing the best operating conditions and LOS F the worst. Each
level of service represents a range of operating conditions and the driver’s
perception of those conditions. Safety is not included in the measures that
establish service levels.
•
Median - A reserved area that separates opposing direction of travel. It may
be a raised or recessed area that is landscaped, or it may be a striped area
on the roadway surface.
•
Mode Split - The estimation of the number of trips made by each mode of
traffic (automobiles, pedestrian, transit, etc.)
•
MUTCD - Manual on Uniform Traffic Control Devices, as approved by the State
of Arizona.
•
Pass-By Trip - Intermediate stops between an origin and a primary trip
destination; for example, a normal home-to-work trip that stops for gas or
coffee. This trip is existing on an adjacent roadway but still shows as entering
and exiting a site access for the proposed development.
•
Peak Hour - The 60-minute interval that contains the largest volume of traffic
during a given time period. An a.m. peak is generally the highest hour in the
morning, and the p.m. peak is the highest in the afternoon.
•
Peak Hour of Generator - The single hour of highest volume of traffic entering
and exiting a site.
•
PHF – Peak Hour Factor – A measure of traffic demand fluctuations within the
peak hour. Determined by adding the total traffic counts in a peak hour (sum
of 4 consecutive 15 min periods) divided by the product of the highest traffic
count in one of those 15-minute segments, within that peak hour, multiplied
by 4.
•
Progression – The process of coordinating traffic signal operations (phasing
and timing) of multiple traffic signals along a corridor to maximize vehicle
throughput along the corridor.
•
Queue Length – The maximum anticipated length of vehicles waiting to
execute a turning movement in the right turn lane or left turn lane under
typical peak hour conditions.
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•
Storage Length – The length of right turn lane or left turn lane that can be
utilized by stopped vehicles waiting to execute a turning movement. Typically
described as the distance from the stop bar to the end of the turn lane stripe.
•
Traffic Impact Analysis (TIA) - A traffic engineering study which determines
the potential traffic impacts of a proposed traffic generator. A complete
analysis includes an estimation of future traffic with and without the proposed
generator, analysis of the traffic impacts, and recommended roadway
improvements which may be necessary to accommodate the expected
traffic.
•
Traffic Statement (TS) - A traffic statement is a smaller version of a TIA. It
typically summarizes the trip generation for the proposed project. It may
provide a comparison of the trip generation for the proposed project against
the land use for the same parcel that was approved in the overall TIA for the
master development. Depending on the proposed project some analyses
may be included in the traffic statement.
•
Traffic Impact - The effect of site traffic on roadway operations and safety.
•
Traffic Generator - A designated land use (residential, commercial, office,
industrial, etc.) or change in land use that generates vehicular and/or
pedestrian traffic to and from the site.
•
Traffic Mitigation - It is the reduction of traffic impacts on roadways and/or
intersections to an acceptable level of service by way of roadway
construction improvements, the upgrade of existing traffic control devices, or
the modification of the site plan.
•
Traffic Generation - The estimation of the number of originations from and
destinations to a site as a result from the proposed land use activity on that
site.
•
Trip Distribution - The allocation of the site-generated traffic among all
possible approach and departure routes.
•
Trip Assignment - The assignment of site plus non-site traffic to specific
streets and roadways.
6-1.003 Design Policy
A. Developers/Landowners are required, pursuant to the City Code, to provide a
Traffic Impact Analysis to show the impact of the development on all existing
and future roads within and adjacent to their sites. The TIA shall be in
accordance with this design standard.
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B. The purpose of a Traffic Impact Analysis is to evaluate the impact of a
proposed development on the surrounding transportation system. Based on
the information provided in the Traffic Impact Analysis, the City determines
the adequacy of the existing or planned transportation improvements by
comparing forecasted directional hourly and daily volumes with the traffic-
handling capacity of an improved facility.
C. Project traffic forecasts and capacity are used to establish the number of
through lanes, length of auxiliary lanes, signal timing improvements, right of
way needs, and other characteristics, so the facility can operate at an
acceptable level of service through the design year or horizon analysis years.
D. This document provides guidance and general requirements for a TIA;
however, specific requirements for a TIA depend on a variety of factors. These
include but are not limited to:
1.
The current transportation system and operational characteristics in the
site vicinity.
2.
The interface between the on-site circulation system and the adjacent
circulation system.
3.
The intensity and character of the proposed development.
4.
The anticipated trip generation potential of the proposed development.
5.
The anticipated directional distribution and routing of project-generated
traffic.
6.
The anticipated geographical extents of the development’s traffic
impact (i.e., influence area).
7.
The roadway improvements the development is responsible for
constructing.
8.
The future roadway improvements that will be constructed by others (or
by the development).
9.
The future trips generated from approved developments that are not
fully built out.
E. Approval of the TIA/TS is required prior to any entitlement on the property
which could be one of the following (whichever comes first), approval of any
Community Master Plan or amendment, preliminary plat, final plat, site plan,
or any other document determining intensity, density or use.
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F. Any modifications to the entitlement at a later stage of the project will require
an updated TIA/TS.
1.
The traffic analysis (report or letter) needs to be updated with current
traffic counts and analyses.
6-1.004 Diligence
A. Developers/Landowners shall verify the need and requirements for a TIA/TS,
as well as roadway and paving improvements that are required to provide
service to a site. It is the Developer’s responsibility to become familiar with all
of the existing site conditions. Available resources in which to find this
information:
1.
Obtain existing as-built drawings.
2.
City’s website – http://www.buckeyeaz.gov
3.
Contact the City to confirm the need for any required traffic analysis.
4.
At the City’s Pre-Application Conference (PAC) it will be determined if a
proposed project needs to produce a Traffic Statement or a full TIA. After
the PAC, it is recommended for applicants to participate in a more
detailed TIA preparation meeting with staff members from the City
Transportation Division. At that meeting, project specific concerns and
nuances can be discussed in detail, and the City will assist in
establishing a general scope and understanding of what is expected in
the TIA or TIS.
5.
Public Records Request
6-1.005 Private Streets
A. All TIA requirements shall apply to all private streets.
6-1.006 Standards
A. The following is a list of national, regional and local resources (the latest
editions unless otherwise stated), which are referenced and used for the
design of streets within the City of Buckeye.
1.
A Policy on Geometric Design for Highways and Streets, AASHTO
2.
Freeway and Interchange Geometric Design Handbook, ITE
3.
Guidelines For Driveway Location & Design, ITE
4.
Highway Capacity Manual, TRB
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5.
Highway Safety Manual, All Volumes, AASHTO
6.
Intersection Design Guidelines, FHWA
7.
Manual of Transportation Engineering Studies, ITE
8.
MUTCD, U.S. Department of Transportation, as approved by the State of
Arizona
9.
Revisions to the MUTCD, U.S. Department of Transportation, by the State
of Arizona; Arizona supplement to the Manual on Uniform Traffic Control
Devices; https://azdot.gov/business/engineering-and-
construction/traffic/traffic-engineering-references
10. Signalized Intersections: Informational Guide, FHWA
11.
Traffic Control Devices Handbook, ITE
12. Traffic Engineering Handbook, ITE
13. Traffic Signal Timing Manual, FHWA
14. Transportation and Land Development, ITE
15. Transportation Impact Analyses for Site Development, ITE
16. Transportation Planning Handbook, ITE
17. Trip Generation, ITE
6-1.100 TIA Reports
6-1.101
General Requirements
A. The following section is a typical layout for each type of report. Modifications
to these requirements may be requested by the City that could include
additional analysis. Modifications may be requested by the applicant for
approval by the City Traffic Engineer.
6-1.102
Traffic Statement (TS)
A. All Traffic Statements shall be sealed and signed on the cover and table of
contents by a registered Professional Civil Engineer in the State of Arizona.
B. Cover Sheet:
1.
Project title
2.
Major cross streets
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3.
Prepared for including: contact name, company name, address,
telephone number, and email
4.
Prepared by including: contact name, company name, address,
telephone number, and email
5.
A Professional Engineer seal (signed)
6.
City approval block (see Figure 1)
7.
All pages of the statement (after the cover page) shall have page
numbers (excluding any attachments).
C. Introduction:
1.
Provide project name, size, description, land use and type of development
2.
Purpose of the statement
3.
Explain the objectives of the statement, defining requirements, satisfy
regulatory requirements and evaluate the impact of the new
development on the existing street systems.
D. Project Location:
1.
Township, Range and Section
2.
Description of the major cross streets
3.
Vicinity Map, including north arrow
4.
Relationship with other developments
a. Provide a map(figure) labeling all adjacent developments and street
network
E. Provide trip generation of the proposed project at build out.
F. When requested, a comparison and summary of the differences in trips
assumed in the original TIA to the actual trips from the known development
type should be provided.
G. When requested, a queuing analysis may be required for a development with
a drive through lane.
H. The City may request other analysis, traffic counts or other requirements
necessary for the TS.
I.
Include as attachments – site plan, trip generation calculations, level of
service calculations, queue length calculations, appropriate information from
previously approved reports, etc.
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J. Provide a recommendation section that will detail results and any
improvements that will be made.
6-1.103 Traffic Impact Analysis / Report
A. All Traffic Impact Analysis Reports shall be sealed and signed on the cover
and table of contents by a registered Professional Civil Engineer in the State
of Arizona.
B. Provide the project title and submittal date on every page of the TIA.
C. Cover Sheet:
1.
Project title
2.
Major cross streets
3.
Prepared for including: contact name, company name, address,
telephone number, and email
4.
Prepared by including: contact name, company name, address,
telephone number, and email
5.
A Professional Engineer seal (signed)
6.
City’s TIA approval block (see Figure 1)
7.
All pages of the report (after the cover page) shall have page numbers
(excluding any attachments)
DISCLAIMER:
THE CITY APPROVES THIS REPORT FOR CONCEPT ONLY AND
ACCEPTS NO LIABILITY FOR ERRORS OR OMISSIONS
BY: _______________________________________________________________
BUCKEYE CITY TRAFFIC ENGINEER
DATE
Figure 1 - TIA City Signature/Approval Block
D. Table of Contents:
1.
List all sections
2.
Figures
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3.
Tables
4.
Appendices
E. Executive Summary Paragraphs:
1.
Project description, location and size
2.
Existing Capacity Analysis
3.
Trip Generation
4.
Future Capacity Analysis
5.
Signal Warrant Analysis, if applicable
6.
Auxiliary Queue Lane analysis
7.
Mitigations, if applicable
8.
Recommendations
F. Introduction:
1.
Provide project name, size, description, land use and type of development
2.
Explain the objectives of the report
G. Project Location:
1.
Township, Range and Section
2.
Description of the major cross streets
3.
Vicinity Map, including north arrow
4.
Relationship with other developments
a. Provide a map(figure) labeling all adjacent developments and street
network
H. Criteria:
1.
All study criteria shall be per this section.
2.
Summarize and include all study criteria used for this report, City of
Buckeye and other agency requirements and criteria.
I.
Proposed Development:
1.
Mention all available information such as location, land use, size, density,
phasing, expected build-out year, access points, hours of operation, peak
periods, and existing land use.
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2.
If project is to be phased, explain the phases and approximate timing of
each phase. Provide a figure or exhibit showing the probable phasing.
J. Area Conditions:
1.
Study Area:
a. The study intersections and streets should be listed in the report. The
size of the study area is generally based on the number of peak hour
trips generated by a proposed development. See Table 1 to determine
the limits of the study area. The study area may be modified by the
City Traffic Engineer due to location and type of proposed land use.
2.
Study Area Land Use:
a. Mention the existing and proposed land uses surrounding the
proposed
development
and
any
anticipated
transportation
connections between the developments
b. Existing/Future land uses on the subject property.
c.
Existing/Future zoning on the subject property.
d. Anticipated future development
3.
Site Accessibility:
a. Area roadway system:
i.
Existing
ii.
Future
iii. Identify any City CIP or other agency/developer project occurring
within the study area
b. Traffic volumes and conditions
c.
Transit service
K. Existing Traffic Counts:
1.
Traffic counts should be taken Tuesday – Thursday of a normal week (not
holiday weeks and nearby schools must be in a normal school session,
unless otherwise approved by the City Traffic Engineer). Typically, this
should be a morning and afternoon peak time, or a time associated with
school release, unless otherwise directed by the City.
2.
State when, where, and how counts were collected and include them in
the Appendix.
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3.
All data shall be collected in accordance with latest edition of the ITE
Manual of Traffic Engineering Studies or as directed by the City.
4.
The data used in the study should have been collected within the past 2
years.
5.
Adjust counts for average conditions due to seasonal differences, when
necessary, if requested.
6.
The directional split should be based on existing conditions. In the case
where existing peak traffic is not available, a 60/40 split should be used.
7.
The peak factor (K) should be based on existing conditions.
L. Projected Traffic:
1.
Site traffic (each horizon year)
a. Trip generation; per nationally accepted methodology (or alternative
method approved by the City Traffic Engineer)
b. Trip distribution
i.
Overall site distribution
ii.
Site access distribution if applicable
iii. Internal trip distribution if requested
c.
Modal split
d. Trip assignment
e.
Apply internal capture and pass by reductions per City Standards or
as directed by the City Traffic Engineer
2.
Background Traffic (each horizon year):
a. Apply City approved growth rate to the existing traffic volumes
collected as part of Section 6-1.103.K.
b. Non-site traffic for anticipated development in study areas:
i.
Trip generation
ii.
Trip distribution
iii. Modal split
iv. Trip assignment
3.
Total Traffic (each horizon year)
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M. Traffic Analysis:
1.
Site Access
a. Driveway spacing
b. Allowable movements
2.
Capacity and Level of Service
a. Graphical or table format acceptable showing LOS and delay in
seconds for each movement and total for each approach and overall
intersection.
b. The LOS shall be calculated and shown for the existing conditions,
opening year, and each future horizon year with and without the
project (if applicable).
3.
Crash Analysis for the last 5 years of crash history
4.
Traffic Signals/All-way stop Warrant Analysis
a. Must include 24-hour data for existing intersection
b. Future warrant analysis must use ADOT TGP 611 for projected volumes.
Other methods may apply if approved by the City Traffic Engineer
prior to the analysis and documentation must be included in the
appendix.
5.
Turn Lane Queue Lengths (including intersections and accesses).
6.
School Site Circulation (for school sites)
7.
Analysis of any pedestrian crossing requirements including pedestrian
crosswalk, RRFB, or HAWK
N. Improvement Analysis:
1.
Improvements for the project shall include the minimum requirements
per City code and any additional improvements to accommodate
horizon year traffic
2.
Provide LOS and capacity of mitigated improvements
O. Findings:
1.
Site accessibility
2.
Traffic impacts
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3.
Need for improvements
a. Timing of phased improvements (tied to number of dwelling units or
square footage of development)
P. Recommendations:
1.
Recommendations shall include a table and/or graphic representation to
specifically detail improvements for the proposed development. These
recommendations are the base requirements for the project’s
construction documents. See Figure 2 at the end of these standards for
an example.
2.
Auxiliary turn lanes (including lengths)
3.
Traffic control devices-signalized or un-signalized
4.
Traffic signal operation (permissive, protected, protected/permissive
phasing, etc.)
5.
Pedestrian and bicycle safety
6.
Traffic mitigation measures
7.
Roadway improvements:
a. On-site
b. Off-site
c.
Intersections
d. Phasing (Timing of phased improvements tied to number of dwelling
units or square footage of development)
Q. Conclusions:
1.
Summarize the work that has been completed.
a. Trip generation
b. Level of service analysis results
c.
Traffic signal warrant evaluations
d. Turn lane queue lengths
2.
Summarize all recommendations and mitigations.
3.
State that all the City requirements as well as all other agencies have
been satisfied.
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R. Appendices:
1.
Include supporting calculations.
2.
List all reference documents in a separate appendix.
3.
Attach all relevant portions of external approved reports, including cover
page, that validate the design of assumptions of this report.
4.
Include all other supporting information.
5.
Include any project related correspondence with the City associated with
this project in a separate appendix. This shall include all variances to City
Traffic Impact Analysis standards.
6.
Include review comments (and responses) from previous submittals.
S. Required Figures:
1.
Site Location – Area map including north arrow showing site location and
area of influence.
2.
Conceptual Plan of Proposed Development – Detailed figure showing
conceptual plan of proposed development including access points,
circulation, and land use components.
3.
Existing Transportation System – Include all major streets, minor streets
adjacent to site, intersection lane configurations and traffic control, and
site boundary. Also show transit, bicycle, and major pedestrian routes, if
applicable, and posted speed limits.
4.
Existing and Anticipated Area Development – Include a Figure or a
bulleted list showing existing and future land uses/developments in the
area.
5.
Existing Traffic Volumes – Include daily traffic volumes and peak hour
traffic volumes. Turning movements are required for the peak hours for all
existing study intersections.
6.
Distribution – Include a Figure showing portion (by percentages) of site
traffic
approaching
and
departing
proposed
development
and
percentage using each driveway, if applicable. Internal site circulation trip
distribution may be requested to be provided.
7.
Site Traffic – Include daily traffic volumes and peak hour traffic volumes
for each horizon year (if separate phasing is expected). Turning
movements are required for the peak hours. Show circled “blow-ups” of
each study intersection on the same figure.
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8.
Background (Future Off-site) Traffic - Include daily traffic volumes and
peak hour traffic volumes for each scenario (horizon year). Turning
movements are required for the peak hours. Show circled “blow-ups” of
each study intersection on the same figure.
9.
Total Traffic - Include daily traffic volumes and peak hour traffic volumes
for each scenario (horizon year). Turning movements are required for the
peak hours. Show circled “blow-ups” of each study intersection on the
same figure.
10. On-Site Circulation (if required by City).
11.
School Site Queuing (for all school sites).
12. Recommended Improvements – Show recommended geometrics, cross
sections and traffic control. Include phasing if applicable and appropriate
triggers for phased improvements.
6-1.200 Traffic Analysis Scenarios
6-1.201
Updating an Existing TIA
A. A TIA may require updating when there are any changes to the proposed
development that are different than the original approved TIA. Generally, a TIA
requires updating every 2 years at the discretion of the City Traffic Engineer, if
there is no progress on the development. For multi-phase developments, an
updated TIA or traffic analysis will be required for each submitted phase or if
specifically identified in governing planning document such as a CMP.
6-1.202 TIA Amendment / Update
A. When only an amendment or update is being sought in a TIA, the following
scenarios are required:
1.
Existing Conditions - Current year traffic volumes and peak hour LOS
analysis of affected transportation network.
2.
Site Traffic, (entire project) only - Trip generation, distribution, and
assignment in the year the project is anticipated to complete
construction.
3.
Background Traffic Only - Trip assignment and peak hour LOS analysis.
Include
current
land
uses
and
other
pending
plan
amendments/anticipated developments.
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4.
Total Traffic (Site Traffic and Background Traffic) - Trip assignment and
peak hour LOS analysis. Include proposed project and other pending plan
amendments/anticipated developments.
5.
Updated recommendations and conclusions.
6.
Updated figures.
6-1.300 Analysis Criteria
6-1.301 Area of Influence
A. Study area of the TIA shall include all study area roadways impacted in
accordance with the criteria in Table 1 or as requested by the City Traffic
Engineer. Traffic impacts include intersections and driveways within the area.
6-1.302 Study Horizon Years
A. The study horizon year is typically the build out year that would be studied
with the development. The horizon years are determined by the project type
and size in accordance with the criteria in Table 1.
1.
Assume full occupancy and build-out for single-phase developments.
6-1.303 Trip Generation Thresholds
A. Table 1 below provides a summary of the criteria for determining the starting
point at which a traffic impact study is required for new developments or
additions to existing developments.
6-1.304 Trip Generation
A. For trip generation forecasts, use the latest edition of the ITE publication, “Trip
Generation”. Other rates may be used with prior approval from the City where
“Trip Generation” does not include trip rates for a specific land use category,
or includes only limited data, or where local trip rates have shown to differ
from the “Trip Generation” rates. Other rates should be developed from
multiple trip generation studies of similar land uses.
B. Each component of land use must be identified by the ITE land use code and
variable number of units or square feet (when applicable), size, and trip
generation. The estimated trip generation must be shown for each analysis
time period. Show trip reductions separately from the “raw” trip generation.
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C. Pass-by Trips:
1.
Pass-by Trips are only considered for retail-oriented development.
Reductions greater than 15% of the projected background traffic will
require consultation and written acceptance by the City Traffic Engineer
prior to submitting the TIA. Include the justification for exceeding a 15%
reduction in the TIA. Pass-by trip reduction cannot be greater than 15% of
the projected background volume for the analysis year.
D. Internal Capture Trips:
1.
Captured trip reductions greater than 5% require consultation and written
acceptance by the City Traffic Engineer prior to submitting the TIA. Include
the justification and written acceptance for exceeding a 5% reduction in
the TIA.
2.
Internal Capture trips are only allowed in mixed use developments and
do not apply to residential only developments.
3.
On multi-phase developments, internal capture will only be allowed if
mixed use is proposed in that phase or constructed with a previous phase
that results in a mixed-use development when completed.
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Table 1 - Analysis Category
NOTES:
1. For Analysis Categories III and IV, an updated analysis will be required as each subsequent
phase comes in for development.
2. For developments projected to generate less than 100 peak trips, a traffic statement will be
required.
3. City Traffic Engineer may amend study area of influence, study intersections and study
type (statement or analysis) as needed for the project.
4. For multi-use developments where a generic ITE land use code was used or the actual
development is a different land use than what was originally assumed in the Master TIA, a TS
will be required to compare the trip generation.
Analysis
Category
Development
Characteristic
Study Horizons
Minimum Study Area
I
Small
Development
(100-499 peak
hour trips)
1. Existing Year
2. Opening Year
1. Site access drives
2. Existing, adjacent signal-controlled
intersections within ¼ mile and/or major street
intersections without signal control and driveways
within 500 feet of property boundaries.
II
Moderate
Development
(500-999
peak hour
trips)
1. Existing Year
2. Opening Year
of each phase.
3. Build Out of
Development
1. Site access drives
2. Existing, adjacent signal-controlled
intersections within ½ mile and/or major street
intersections without signal control and driveways
within ½ mile of property boundaries.
III
Large
Development
(1000-1500
peak hour
trips)
1. Existing Year
2. Opening Year
of each phase.
3. Build Out of
Development
1. Site access drives
2. Existing, adjacent signal-controlled
intersections within 1 mile and/or major street
intersections without signal control and driveways
within 1 mile of property boundaries.
IV
Regional
Development
(>1500 peak
hour trips)
1. Existing Year
2. Opening Year
of each phase.
3. Build Out of
Development
1. Site access drives
2. Key signal-controlled intersections and major
street intersections without signal control within 3
miles of property boundaries.
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6-1.305 Trip Distribution and Assignment
A. Projected trips shall be distributed and added to the projected non-site traffic
on the roadway network.
1.
Consultation between the City Traffic Engineer and those preparing the
TIA is recommended to understand the current and projected future
transportation network. For example, the City currently has a strong
employment draw to the east, with Interstate 10 (I-10) being the primary
route.
B. Projected trips shall be distributed based upon projected population areas,
employment areas, and market areas of commercial developments.
1.
The trip distribution shall be evaluated for each horizon year.
2.
The specific assumptions and data sources used in driving trip
distribution and assignment shall be documented in the report.
6-1.306 Capacity Analysis
A. Level of service shall be computed for signalized and unsignalized
intersections as identified in Table 1 (or as amended by the City Traffic
Engineer), in accordance with the latest edition of the Highway Capacity
Manual.
B. For all intersections evaluated, operational analyses shall be performed for
horizon analysis years required in Table 1. Operational analyses shall also be
performed for street sizing.
C. When required by the City Traffic Engineer, capacity analysis of adjacent
roadways or roadways within developments (such as Community Master
Planned developments) must be analyzed using City criteria for LOS D
capacity of specific roadway classifications.
D. The latest version of synchro analysis software must be used for all capacity
analysis. The files used will be provided to the City prior to approval of the
TIA/TS.
E. Peak Hour Factor (PHF) used for future conditions shall not exceed 0.90. The
following PHF shall be used unless otherwise directed by the City:
1.
PHF = 0.80 for < 75 vph per lane
2.
PHF = 0.85 for 75 – 300 vph per lane
3.
PHF = 0.90 for > 300 vph per lane
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6-1.307 Right Turn on Red Reduction
A. Prior approval must be obtained from the City Traffic Engineer before a right
turn on red reduction is implemented for any analysis.
6-1.308 Traffic Counts
A. Prior to field traffic counts, consultation between the City Traffic Engineer and
those preparing the TIA is recommended to determine the level of detail
(location, travel speeds, turning movement counts, and so forth) required at
each traffic count site. Guidelines for counting vehicular traffic include, but
are not limited to, the following:
1.
Conduct daily vehicle counts when school is in session and include
vehicle classification for at least one contiguous 24-hour period on a
Tuesday, Wednesday, or Thursday. Counts should be taken during weeks
not containing a holiday and in favorable weather conditions. There
should not be any lane restrictions during the data collection period.
2.
Where appropriate, consider seasonal and weekend variations in traffic,
such as recreational routes, and tourist seasons.
3.
The use of existing traffic counts, traffic counts from other studies, or
historic traffic counts will require approval from the City, prior to
submitting the TIA.
6-1.309 Peak Traffic Hours
A. In general, the TIA includes analyses for both morning (a.m.) and evening
(p.m.) peak hours. The minimum peak hours shall be from 6-9 a.m. and 4-7
p.m., reflecting the City’s typical traffic patterns. For school projects, the
analysis should also include 2-4 p.m. Other peak hours, such as weekends or
peaks from specific uses, may be required to assess the project’s traffic
impacts, as applicable.
6-1.310 Seasonal Adjustments
A. The traffic volumes for the analysis hours should be adjusted for the peak
season if appropriate. The use of seasonal adjustments factors requires the
approval of the City Traffic Engineer. The intent is not to assess maximum
peak hourly volumes, such as the day after Christmas for a retail
development, but to address peak seasonal volumes. If traffic counts were
collected in a retirement community in July, and the peak traffic period
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occurs during the winter months, the counts shall be adjusted to winter
months.
6-1.311
”K”-Factor
A. The peak factor (K) should be based on existing conditions. The K-factor
calculated from existing traffic counts, for converting ADT to peak hour
volumes, shall range from a minimum of 0.07 to a maximum of 0.10.
B. If peak hour traffic data is not available and it is requested to use projected
daily volumes, 8% of daily traffic should be used for the morning peak hour
and 9% for the evening peak hour.
6-1.312
Data Collection Requirements
A. All data shall be collected in accordance with the latest edition of the ITE,
Manual of Transportation Engineering Studies or as directed by the City Traffic
Engineer.
B. Turning Movement Counts (TMC):
1.
Turning movement counts shall be obtained for all existing study
intersections to be analyzed during the specified morning and afternoon
peak periods, as well as the peak hour of the generator. Additional turning
movement counts may be required during other periods, as directed by
the City Traffic Engineer.
2.
Available turning movement counts may be extrapolated a maximum of
two years with the concurrence of the City Traffic Engineer.
C. Daily Traffic Volumes:
1.
The current daily traffic volumes, including vehicle classification, shall be
presented in the report.
2.
Traffic volume estimates from other approved developments or those in
the planning stage within the study area, which are expected to occur
during the study horizon years, should be obtained from the City through
a Public Records Request (PRR) for the relevant developments. These
estimates should be presented in the report as part of the background
traffic volume.
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D. Crash Data:
1.
Crash History:
a. Traffic accident data shall be obtained from the City or ADOT for the
most current 5-year period available.
2.
Collision Diagram:
a. A collision diagram shall be provided illustrating the 5-year crash
history at each location where the number of collisions at the location
has been 25 or more in the last 5 years.
3.
Collision Types and Locations:
a. Identify the predominant collision types and their locations, any
patterns, and an assessment of and mitigation for the development’s
traffic safety impacts. Collision discussion shall also include
information on sight distance and any other pertinent roadway
geometrics and/or traffic control.
E. Traffic Control Devices:
1.
The location and type of traffic control devices shall be identified.
6-1.313
Traffic Signal Warrant Analysis
A. Consultation between the City Traffic Engineer and those preparing the TIA is
recommended during the early planning stages of a project, to determine the
need for Traffic Signal Warrant Analyses.
B. A Traffic Signal Warrant Analysis shall be conducted for all arterial/arterial,
arterial/collector and collector/collector intersections within the study area
for the opening year, buildout and any subsequent phases of a multi-phase
development. Other intersections may be requested by the City Traffic
Engineer depending on the type, density, and trip generation of a
development.
C. Typical traffic signal spacing is at ½ mile intervals. In rare situations, the City
may approve signals at ¼ mile spacing and possibly other spacing for unique
situations.
D. Traffic signals may only be installed when the minimum criteria in the MUTCD
are met and are approved by the City.
E. The following are the minimum warrants to be analyzed for all traffic signals:
the 8-hour, 4-hour, peak hour, and crash warrants.
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F. When hourly traffic counts are not available refer to the ADOT Engineering
Policies, Guidelines and Procedures Section 611 Figure 611-A for AADT hourly
adjustment factors.
6-1.314 Traffic Impact Analysis Methodologies
A. Typically, the traffic analysis methodologies for the facility types indicated
below are used by the City and will be accepted without prior consultations.
1.
Signalized Intersections: HCM, operational analysis, Synchro
2.
Un-signalized Intersections: HCM for capacity and MUTCD for signal
warrants (if a signal is being considered), Synchro
6-1.315 Mitigation Measures
A. Mitigation measures must be included in the TIA to determine whether a
project’s impacts can be eliminated or reduced to a level of insignificance.
B. When the analyses indicate that a particular location will operate at an
acceptable level of service, no improvements beyond those required by city
code will be required. If, however, deficiencies are revealed by the analysis
results, then improvements in access, geometry, or operations must be
investigated.
When
reasonable
improvements
cannot
sufficiently
accommodate projected traffic, more detailed assessments of project size,
land use, or development phasing may be required.
C. Large and/or multi-phase development projects will often necessitate
significant on-site and/or off-site transportation system improvements prior
to reaching a full-buildout condition but may not necessitate all these
improvements being constructed with/before the first phase of development.
Either way, all of the improvements necessary to accommodate a full buildout
condition, as well as all improvements necessary to appropriately mitigate
the anticipated impacts of the proposed development must be identified in
the report. In addition, if any phasing of the ultimately necessary
improvements is proposed, the report shall include an explanation as to the
timing of the improvements in relation to both the phasing of the
development, and any pertinent anticipated changes within the study area
as a whole.
6-1.316 Proposed Development - Mode Split
A. If a mode other than vehicular travel is expected to be significant, the City
must approve assumptions and any reductions applied to vehicular traffic.
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6-1.317
Level-of-Service (LOS) Analysis
A. LOS analysis must be performed for the analysis time periods for each study
intersection and site access in accordance with the latest edition of the
Highway Capacity Manual.
B. Each analysis scenario (horizon year) should be analyzed with and without
recommended improvements.
C. The level-of-service calculations must be included in the report appendix.
D. The City requires a minimum of a LOS ‘D’ for total intersection and all
movements at both signalized and un-signalized intersections during the
peak hours for every analysis year. Individual movements or approaches that
are LOS E or F may be allowed but also may require mitigation.
6-1.318 Turn Lane Storage Analysis
A. The minimum right-turn and left-turn lane storage lengths are provided in
City Design Standards Section 6-3 Street Planning and Design Criteria. Section
6-3 also covers when turn lanes are required.
B. Recommended storage lengths should be included in the report; however, the
City’s minimum storage length requirements must be met, unless otherwise
approved by the City Engineer.
C. Single Right Turn and Left Turn Lanes:
1.
Design shall be per the AASHTO Method with a modification factor as
described below.
2.
Maximum length of a single left turn lane is 300 feet.
a. The following criteria apply to un-signalized intersections:
i.
Highest peak hour turning volume
ii.
2-minute queue interval
iii. Queue factor of one and a half (1.5)
iv. Design vehicle lengths
1.
All streets except commercial and industrial streets and truck
routes – 25 feet.
2.
Commercial, industrial streets, and truck routes – 40 feet.
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b. The following criteria apply to signalized intersections:
i.
Highest peak hour turning volume
ii.
120 second cycle length
iii. Queue factor of one and a half (1.5)
iv. Design vehicle lengths
1.
All streets except commercial and industrial streets and truck
routes – 25 feet.
2.
Commercial, industrial streets, and truck routes – 40 feet.
D. Dual Right Turn and Left Turn Lanes:
1.
Dual turn lanes are only allowed at signalized intersections.
2.
Permissive dual left turns are prohibited unless approved by the City
Traffic Engineer.
3.
Design shall be per the AASHTO Method.
a. The following criteria apply to signalized intersections:
i.
Highest peak hour turning volume
ii.
120-second cycle length
iii. Queue factor of one and a half (1.5)
iv. Design vehicle lengths
1.
All streets except commercial, industrial or truck routes shall
utilize 25 feet.
2.
Commercial, industrial streets shall utilize 40 feet.
3.
Truck Routes determined by study but in no case less than 30
feet.
E. Example Equation: Highest peak hour /30 (interval)*1.5*25’
a. Example: If 200 is the highest peak hour left turn volume:
200/30= 6.7 vehicles, round up to 7 vehicles
7*1.5*25=262.5’, round to 275’ queue storage needed (next highest
25’ increment)
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6-1.319
Improvement Analysis
A. The anticipated results of any proposed or planned transportation
improvements must be provided in the conclusion and executive summary
section of the report. This should be provided in a table or bulleted list and/or
graphic representation. See example provided at the end of this document in
Figure 2. The engineer may also recommend changes to planned
improvements that may result in improved operating characteristics of the
transportation system.
6-1.320 Additional Criteria for School Sites
A. School sites include schools with students in any of the grades K through 12,
including public, private and charter schools.
B. The TIA shall identify the maximum student enrollment conditions:
1.
The maximum student enrollment, including enrollment per grade if
students are in grades 9-12, shall be identified in the TIA.
2.
The on-site peak hour vehicle queue lengths shall be calculated and
included in the TIA, and shown on a figure.
a. The City has a minimum requirement for on-site vehicle queuing for
student drop off/pick up at all schools. The minimum requirement
should be verified in a separate section of the TIA dedicated to
student drop-off/pick up queuing analysis. The following are the
minimum requirements for queuing:
i.
Schools located on Arterial roads – 5’ of queuing per student at full
enrollment.
ii. Schools located on Collector roads – 4’ of queuing per student at
full enrollment.
iii. Student enrollment determined as follows:
1.
K-9th grade – every student anticipated.
2.
10th grade – ½ of student body anticipated if student parking
is provided for 10th grade students, otherwise all of the 10th
grade students are included in the queuing calculation.
3.
11th grade – ¼ of student body anticipated if student parking
is provided for 11th grade students, otherwise all of the 11th
grade students are included in the queuing calculation.
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4.
12th grade is presumed to have one parking space per
student. If a parking space is not provided for each 12th grade
student, then the difference between the number of 12th grade
students and provided parking spaces for 12th grade students,
shall be included in the queuing analysis.
b. The City has a minimum requirement for on-site student parking for
all schools. The intent for providing adequate student parking is for
the school to be a “good neighbor” to those around the school and
not have students parking within the adjacent developments. The
minimum requirement should be verified in a separate section of the
TIA dedicated to student parking analysis. The following are the
minimum requirements for student parking:
i.
10th Grade Students – 0.5 parking spaces for each student (total
enrollment of grade).
ii.
11th Grade Students – 0.75 parking spaces for each student (total
enrollment of grade).
iii. 12th Grade Students – 1 parking space for each student (total
enrollment of grade).
iv. If alternative operations or school provided transportation
options are available, the required number of parking spaces can
be reduced with approval by the City.
3.
The on-site circulation of the school site shall be evaluated and shown on
a figure.
6-1.400 Traffic Analysis Software
6-1.401 Trafficware – Synchro
A. Synchro is a software application for optimizing traffic signal timing and
performing capacity analyses on a microscopic level. Synchro performs
capacity analyses using both the ICU and HCM methods.
B. Complete Synchro model files will be required to be submitted with the TIA
when requested by the City prior to the approval of the TIA.
6-1.402 Trafficware – SimTraffic
A. SimTraffic is a software application for simulating traffic operations on a
microscopic
level.
SimTraffic
models
signalized
and
un-signalized
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intersections with cars, trucks, pedestrians, and buses. SimTraffic can use
data files created in Synchro.
B. SimTraffic simulations may be required in some circumstances, to
supplement the Synchro traffic analysis output, or to provide animations that
illustrate the operation of a project.
Figure 2 - Example Graphical Representation of Improvements
Table 2 - Example Table of Recommendations
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6-1.500 Master Traffic Impact Analysis for CMPs
6-1.501 General Information:
A. A Master Traffic Impact Analysis is required for all CMPs. The plan must show
the proposed alignment for all arterial and collector streets within and
adjacent to the CMP. The design of the streets will be based on the current
City Council approved Transportation Master Plan and associated Street
Classification Map, existing improvements and the approved Traffic Impact
Analysis.
B. The Master Traffic Impact Analysis shall be updated per the Development
Agreement(DA), stipulations and at a minimum with each phase of
development. This includes showing all current conditions and complying
with the City’s current design standards as applicable per the CMP and DA.
C. All requirements of the TIA will be defined at pre-application meeting or as
defined in this document for a TIA. Additional requirements may be requested
by the City Traffic Engineer depending on the CMP.
[End of Section]