Traffic Impact Report Preparation Guidelines by set6tyhsd


									Traffic Impact Report
Preparation Guidelines

Adopted in July 1999

        City of Pasadena
        Department of Public Works & Transportation

        Transportation Division
            City of Pasadena
            Department of Public Works & Transportation

                             GUIDE FOR THE PREPARATION OF
                                TRAFFIC IMPACT REPORTS

The City of Pasadena Department of Public Works and Transportation has established
a procedure for the preparation of project traffic impact reports to ensure consistency of
analysis and adequacy of information presented. This guide is to be used for the
preparation of traffic reports, and the reports will be prepared in the format presented

A traffic study is to be conducted and a subsequent report submitted for any project
requiring a Conditional Use Permit if the project size or traffic generation exceeds
specified minimum criteria. The applicant will provide the traffic study, prepared by a
registered (State of California) traffic engineer. To avoid unnecessary delays or
revisions, it is strongly recommended that the applicant or his/her traffic engineer
contact the Transportation Division before beginning the study to discuss traffic demand
and capacity assumptions and other study requirements for the project.


The following is a description of the methodology for calculating the level of impact due
to traffic generated by the proposed project.

Intersection Capacity Analysis (ICU Impact Thresholds):

The City of Pasadena uses a sliding scale to assess intersection impacts. The sliding
scale method would require a developer to mitigate the project’s traffic impact whenever
the traffic generated by the proposed development causes the Level of Service (LOS) of
the identified intersection to increase by an amount equal to or greater than the amount
listed in the following table:

                        Intersection Level of             Increase in Intersection
                           Service Under                  Level of Service Due to
                         Current Conditions                    Project Traffic
                                                          Considered Significant
                                     A                             0.060
                                     B                             0.050
                                     C                             0.040
                                     D                             0.030
                                     E                             0.020
                                     F                             0.010

July 1999                                                                            Page 1 of 4
            City of Pasadena
            Department of Public Works & Transportation

Street Segments (ADT Impact Thresholds)

The following are thresholds for impacts to any street segment by a development
project (excluding ambient growth) and the required traffic mitigation:

     ADT Growth on Street Segment                             Required Traffic Mitigations
0.0 - 2.4% ADT Growth
    • Project review and Initial Study                    •   Staff Review and Conditions
2.5% - 4.9% ADT Growth
   • Examined by Initial Study                            •   Soft Mitigation Required
   • Focused Traffic Study                                •   TDM, Rideshare, etc.

5.0% - 7.4 % ADT Growth                                   •   Soft Mitigation Required
   • Examined by Initial Study                            •   Physical Mitigation Required
   • Full Traffic Study Required                          •   Project Alternatives Considered
7.5% + ADT Growth                                         •   Soft Mitigation Required
   • Examined by Initial Study                            •   Extensive Physical Mitigation
   • Full Traffic Study Required                              Required
                                                          •   Project Alternatives Considered

1. Study Area Boundaries

   All critical intersections and street segments within the primary influence area of the
   proposed development are to be evaluated.

   Critical intersections and locations include: (a) all signalized intersections in which
   site traffic comprises at least two percent (2%) of the existing capacity of any
   approach: and (b) any roadway section impacted by any development traffic, and
   any location identified by the City Traffic Engineer.

2. Study Periods

   The highest demand for travel generally occurs during the evening peak-travel
   period. Therefore, weekday PM peak hour will he evaluated for all office and
   commercial uses. In some instances, the AM peak period may he critical, or night or
   weekend traffic may he a problem. The City Traffic Engineer will require evaluation
   of all critical time periods based on the site location and proposed uses. Unless
   otherwise specified, peak hours occur between 7:00 and 9:00 a.m. and between
   4:00 and 6:00 p.m. Mixed use or retail/commercial developments ma require multiple
   peak hours to he analyzed.

July 1999                                                                                Page 2 of 4
            City of Pasadena
            Department of Public Works & Transportation

3. Site Traffic Forecasts

   The projected travel demand for each development must be based upon recognized,
   applicable data. The Trip Generation Manual, current edition, published by the
   Institute of Transportation Engineers, is used as the primary document. Other trip
   production rates can be used if approved by the City Traffic Engineer.

   Any adjustments to standard rates, such as for special uses, mixed uses, high transit
   use, or pass-by trips must be approved by the City Traffic Engineer.

4. Traffic Dis tribution

   The traffic distribution is a prediction of the future travel paths of site users. It is
   generally based on population distribution and significant travel paths in the study
   area. The trip distribution is to be approved by the City Traffic Engineer prior to
   preparation of the report.

5. Ambient Grow/It Factor

    The ambient growth factor to be used in determining future base traffic volumes will
   normally range from one to two percent per year. The City Traffic Engineer will
   determine the ambient growth factor to be used based on the location of the
   proposed project.

6. Parking Analysis

   The traffic study should include an analysis of parking demand for the proposed
   project and should also include information regarding how the project will
   accommodate the parking demand. Shared parking analysis should also be included
   if applicable.

7. Review by the Traffic Engineer

   The basic assumptions of the traffic study are to be reviewed by the City Traffic
   Engineer prior to substantial work on evaluation and development of possible
   mitigation. This is to ensure that the study conforms to appropriate standards and

8. Assignment and Analysis

   After the City Traffic Engineer has agreed to the report assumptions, site traffic may
   be applied to the street network and the level of service determined at each critical
   location for:
           • Current (cumulative plus existing): and
           • Current plus project.

July 1999                                                                       Page 3 of 4
            City of Pasadena
            Department of Public Works & Transportation

   The ICU method is used for evaluation. The technique is used by most cities in the

9. Mitigation Measures

   Developments, which cause any degradation of traffic operation, must mitigate the
   problems caused by their development. Mitigation measures are required when
   level of service at any study intersection is increased by an amount greater than or
   equal to the significant values shown in the sliding scale and if the ADT growth
   exceeds the threshold for impacts.

   If mitigation measures are necessary, the maximum ICU value provided by the
   mitigation measures are to be presented. If mitigation reflects trip reductions
   predicted as a result of implementing required TDM measures, an approved report
   must be submitted substantiating such mitigation.

   All proposed roadway mitigation must be illustrated and a preliminary cost estimate
   provided to show the new intersection configuration, including lane widths,
   assignments, widenings, and trip reduction attributed to required TDM strategies.

10. Site Traffic Requirements

   The evaluation process must include site design features which may impact local
   traffic operation, including:

            a.   Location and design of access points;
            b.   Vehicle queuing requirements and provisions;
            c.   Internal circulation and parking;
            d.   Service and docking plans;
            e.   Parking design; and
            f.   Carpool/vanpool loading areas.

11. Report Review

   The report will be reviewed by the City for accuracy, completeness and approval of
   assumptions made throughout the report. Mitigation measures recommended in the
   report and assumed impact will also be reviewed. Should the report not meet the
   satisfaction of the City, the report will be returned with appropriate comments for
   further evaluation.

12. Report Approval

   When the Traffic Impact Report has been checked and found satisfactory, a letter of
   approval shall be issued by the City Traffic Engineer.

July 1999                                                                    Page 4 of 4

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