Chapter 6 Mobility Standards Appendix 6E Guidelines for Traffic Impact Studies and Air Quality Analysis Page4 of 6

TABLE A-l

LEVEL OF SERVICE CRITERIA FOR SIGNALIZED INTERSECTION

LEVEL OF
SERVICE		 DESCRIPTION
A. Describes operations with very low delay, i.e., less than 5.0 seconds per vehicle. This occurs when progression is extremely favorable, and most vehicles do not stop at all. Short cycle lengths may also contribute to low delay.
B. Describes operations with delay in the range of 5.1 to 15.0 seconds per vehicle. This generally occurs with good progression and/or short cycle lengths. More vehicles stop than for LOS A, causing higher levels of average delay.
C. Describes operations with delay in the range of 15.1 to 25.0 seconds per vehicle. These higher delays may result from fair progression and/or longer cycle lengths. Individual cycle failures may begin to appear in this level. The number of vehicles stopping is significant at this level, although many still pass through the intersection without stopping.
D. Describes operations with delay in the range of 25.1 to 40.0 seconds per vehicle. Longer delays may result from some combination of unfavorable progression, long cycle lengths, or high V/C ratios. Many vehicles stop, and the proportion of vehicles not stopping declines. Individual cycle failures are noticeable.
E. Describes operations with delay in the range of 40.1 to 60.0 seconds per vehicle. This is considered to be the limit of acceptable delay. These high delay values generally indicate poor progression, long cycle lengths, and high V/C ratios. Individual cycle failures are frequent occurrences.
F. Describes operations with delay in excess of 60.0 seconds per vehicle. This is considered to be unacceptable to most drivers. This condition often occurs with over-saturation, i.e., when arrival flow rates exceed the capacity of the intersection. It may also occur at high V/C ratios below 1.00 with many individual cycle failures. Poor progression and long cycle lengths may also be major contributing causes to such delay levels.

SOURCE: Highway Capacity Manual. Special Report 209, Transportation Research Board, Washington, D.C., 1985.

APPENDIX B
STUDY ELEMENTS

The following items should be included in the impact studies submitted to the Jefferson County Public Works and Transportation Division and the Air Pollution Control District of Jefferson County.

  1. Text

    The text should be brief and to the point. It should be presented in numbered sections which contain the information as outlined below:

    Part One: Traffic Impact Studies

    Section 1: Introduction — this section should identify clearly the developer of the proposed development and the consultant performing the analysis. It should also provide a description of the site's location, using a location map to depict its location in Jefferson County. In addition, this section should detail the site's current zoning, any proposed zoning changes, zoning of the surrounding area and the total acreage to be developed. The Comprehensive Plan recommendations for the proposed site should also be described in this section. In addition, this section should briefly describe the proposed project in terms of total square footage, by land use, or the number of dwelling units to be constructed. This description also should include the proposed construction schedule and the number of units, by land uses, to be constructed in each development phase.

    Section 2: Section two of the report should describe the data collection process, that is, the type of data collected and when, if necessary, traffic counts were taken. This section should also include a description of the relationship between the site and the existing transportation system. This should include driveway locations, existing geometry, average daily traffic, lane configurations, traffic control devices at critical intersections, and existing and expected future functional classifications, as presented in the Comprehensive Plan Core Graphics. If applicable, the availability of public transit to the site should also be discussed.

    Section 3: This section should indicate the procedures used in the analysis, street segment(s)/intersection(s) to be analyzed, trip generation rates used and their source, time period(s) to be analyzed, and the range of trip reassignments for pass-by, diverted, and trip reductions for internal circulation, identifying the source of the rates used, expected traffic entering and exiting the site, and the assignment of those trips to the street system, expressed as a percentage of total new trips generated.

    Section 4: Discussion of the results for each condition analyzed should be submitted in section 4. A subsection should address committed roadway and intersection improvements in the area and their effect on the proposed development. If the street segment(s)/intersection(s) are scheduled for improvement, a description of these improvements and the expected completion date should be included. Planned roadway or intersection improvements may also be identified in this section. However, planned improvements may not be considered in the analysis of the proposed development. Only projects committed to by the state, county or local jurisdiction should be considered. In addition to committed improvements additional mitigation measures should be identified, if necessary. Analysis should be conducted and compared with results without these measures. Tables comparing the analysis results; should be presented within this section, and detailed result should be presented in the appendices of the report.

    It should be the goal of any proposed mitigation measure to maintain an acceptable V/C ratio and level of service at all critical intersections. Whenever feasible, mitigation measures should be developed to ensure that resulting conditions at the critical intersections are no worse than currently exist or are expected to exist with committed improvements without the proposed development. .It is realized that this is not always possible or desirable; therefore, the main objective is to maintain an acceptable V/C ratio for the intersection. Detailed supporting data and analysis results used in the determination of mitigation measures should be submitted to PW&T under separate cover.

    Section 5: The final section should briefly describe the roadway system's ability to handle the traffic generated for each condition analyzed. Identify needed street improvements over and above those currently programmed and a reasonable cost estimate for making the improvements. This section should also be used to document reasons for those street improvements above those currently programmed.

    Part Two: Air Quality Analysis

    The air quality analysis should be well documented, however, the text should be brief. The CAL3QHC modeling printouts provide most of the details needed for review and verification by the APCD. A diskette containing the data used for the CAL3QHC model runs should be provided. The text of the impact report should summarize the analysis. The certified air quality analyst should be identified in the report.

    Section 1: Briefly described the process and in making the air quality analysis. If the procedure in the guideline were followed, a statement to that effect is all that is needed for this Section. Tables or maps describing the input or output of the model should be referenced. Should a value not recommended in the guidelines be used, the full documentation justifying the deviation should be presented here. (Caution: Although the documentation is presented in this report the approval to deviate from the guidelines must be obtained prior to the analysis.)

    Section 2: The conclusions and findings relative to air quality are presented here. Mitigation measures proposed by the developer to reduce air quality impacts should be described. If the mitigation measure is to be implemented by someone or agency other than the developer an official statement must be included (letter of commitment) from the other party.
  2. Maps

    The following maps, as a minimum, should be provided for reference with the impact study report submitted for review and acceptance.
    1. An area or location map which locates the proposed development in the context of the existing area wide street system.
    2. A site plan of the proposed development which identifies the proposed land uses, access to the site from the existing roadway system, the proposed internal circulation system, parking layout and parking breakdown, (number of spaces required and number of spaces provided), as defined in Article 10 of the Louisville/Jefferson County Zoning Regulations.
    3. A map of the traffic impact area which identifies existing roads in the area, the proposed development, critical intersections and other approved projects in the area using the following status categories:
      1. under construction
      2. zoning and/or construction approval
      3. proposed, but not yet approved.
    4. A map which identifies committed roadway improvements, if any, that are included in the Regional Transportation Improvement Program, the Commonwealth of Kentucky's Six Year Plan or identified by the Director of Public Works, which may affect traffic at the critical intersection(s) being studied.
    5. A map which identifies existing A.M. and/or P.M. peakhour traffic volumes assigned to the affected street system. (NOTE: Both volumes, if needed, may be presented on the same map).
    6. A map which identifies the trip distribution pattern, as a percent of total traffic generated, for the proposed development during the time period(s) agreed upon.
    7. A map which identifies the trip distribution pattern, as a percent of total traffic generated, for approved projects in the impact area during the time period(s) agreed upon.
    8. A map which identifies the actual traffic volumes generated by the proposed site and other approved projects within the impact area assigned to the affected street system for the time period agreed upon. The map should distinguish between the two sources of traffic and identify the sum of the two.
    9. Scaled drawings (1" = 50') of critical intersections with a grid overlay showing the location of the receptors, distance to adjacent intersections, length of storage lanes, and location of stop bar.
  3. Tables and Figures

    The following is a minimum list of tables and figures which should be included in a traffic impact study within Jefferson County.
    1. A table which provides the following information about the land uses/trip generation characteristics of the traffic impact area identified in Map 3.
      1. ITE land use code used in the study;
      2. Units to be developed (sq. ft., D.U., etc);
      3. Trip generation rate/trip ends generated (for the adjacent street peak hour, entering/exiting the facility for the period(s) analyzed);
      4. Reassignment rates for pass-by, and diverted trips and reduction rates for internalcirculation;
      5. Total new Trip ends added to the new existing (and/or committed) street system.
    2. A table which summarizes the volume-to-capacity ratios delay and level of service for each of the critical intersections, by approach and movement, for each of the conditions analyzed.
    3. Diagrams of the existing geometry and lane utilization for the road segment(s) and/or critical intersection(s) being analyzed.
    4. Diagram of the improved geometry and lane utilization for the road segment(s) and/or intersection(s) being analyzed. Diagrams identifying both planned improvements and mitigation measures should also be provided.
    5. A receptor location description table (including coordinates).
    6. Tables showing maximum 1-hour and 8-hour concentrations (including background) at each receptor point.
    7. Modeling printouts with input listing and output files showing maximum concentration calculated. Should be submitted as a separate document.
  4. Appendix

    The Appendix should include the output summary from the Highway Capacity software, or, if other procedures are used, equivalent documentation which would permit PW&T staff to easily replicate the procedures. Documentation should be provided for each condition analyzed. (Detailed results from the Highway Capacity Software should be provided under separate cover to PW&T).

    All relevant data necessary to conduct an analysis using the Highway Capacity software should be provided within the Appendix. This data includes assumptions or actual counts of truck and transit traffic, right turns on red, pedestrian traffic and parking maneuvers. This data should also include a diagram showing the iissumed phasing and timing for each signalized intersection analyzed. (If actual signal phasing and timings are used, phasing diagrams and time charts should be provide under separate cover to PW&T).

    If the intersection level of analysis is being performed, existing intersection turning movement counts for the time period(s) analyzed should be included for each intersection. The counts should be presented in such a fashion mat the PW&T staff may determine the peak traffic hour for the time period(s) analyzed. In addition expected peak hour turning movement counts should also be provided for each critical intersection for the total build condition. If the project is to be constructed in phases, expected peak hour turning movements should be provided for each phase. A sample turning movement summary sheet is provided in Appendix D, Figure 2. This example provides a summary of all data required to determine the expected peak hour turning movements.

    It is also requested that copies of the original turning movement field sheets be provided, under separated cover, to the PW&T staff. It is requested that these counts be summarized in 15 minute intervals. The purpose of this request is to develop a historical turning movement count file throughout Jefferson County. This data will be useful in more accurately determining the impacts of future development in the area and provide Jefferson County and developers with an accessible traffic count database. The recommendation for the installation of a traffic control signal and the estimated cost for installation should be presented within the text of the report, with other recommended improvements.

    If the petitioner or the consultant feels that the installation of a new traffic control signal is warranted, documentation supporting this recommendation should be provided in the Appendix. This documentation should include a discussion of the signal warrant expected to be satisfied and the methodology used in that determination. This narrative should be supported with tables and figures that clearly present any assumptions, calculations and results used in the analysis. Reference material used for this analysis should also be noted

    In addition, possibilities of providing an interconnect signal system or to provide optimum signal progression should be discussed. Figure 3 of Appendix D provides an example of the type of table that should be present in this analysis to support the justification of signal installation.