Level of Service Analysis Procedure
Traffic analysis should be prepared under the direction of a registered traffic engineer, registered civil engineer, or qualified transportation planner. The analyst and project applicant shall meet with Planning Department staff and Public Works staff to identify the study area, assumptions, and methodologies for the traffic analysis. All assumptions and methodologies of the LOS analysis are subject to review and approval by the City Traffic Engineer.
A transportation study (TS) that includes LOS analysis is required for a proposed project that meets any of the following criteria:
- Generates more than 100 vehicle trips during either the AM or PM peak hours.
- Adds 51 or more trips during either the AM or PM peak hours to any intersection.
- Proposes variations from the standards and guidelines provided in this manual.
- Is determined by the City Traffic Engineer to warrant evaluation due to existing or proposed traffic conditions in the project vicinity.
Traffic Counts
Traffic analysis should not use traffic counts older than two years without approval from the City Traffic Engineer. If recent traffic counts are unavailable, new counts should be collected by a qualified data collection firm. Turning movement data at study intersections should be collected in 15-minute intervals during the hours of 7:00 AM to 9:00 AM and 4:00 PM to 6:00 PM, unless otherwise specified by the City Traffic Engineer. Traffic counts should generally be conducted when local schools or colleges are in session, on days of good weather, from Tuesday to Thursday during non-summer months, and should avoid holiday weeks.
Trip Generation
The City will accept trip generation rates from the latest edition of the Trip Generation Manual published by the Institute of Transportation Engineers (ITE). For proposed projects with trip generation rates not provided in the ITE manual, rates from other agencies or locally approved studies may be used, provided documentation supporting these rates is included.
The traffic analysis should justify trip generation credits such as existing uses, transit, and internal capture. Pass-by traffic credit should be calculated based on ITE data or City-approved special studies.
Trip Distribution and Assignment
A description of trip distribution and assignment for vehicle trips to and from the site along specific roadways is required. The basic methodology and assumptions used to develop trip distribution and assignments must be clearly stated and approved by the City Traffic Engineer. The basis for trip distribution should be linked to demographic or market data and consider the project’s location relative to the regional roadway system.
Trip assignment should be based on existing and projected travel patterns, the future roadway network, and its travel time characteristics. It should incorporate the trip generation of the project minus the appropriate credits.
Traffic Forecasts
The traffic analysis should include total traffic expected at the buildout of the proposed project, considering all cumulative effects. The ambient growth rate in the project vicinity can be obtained from the City’s General Plan, the latest version of the Southern California Association of Governments (SCAG) Travel Demand Model, or another appropriate sub-area travel demand model. Approved or planned projects not yet built in the vicinity should be verified and included in the analysis with approval from the City Traffic Engineer.
Analysis Methodologies
The City will use the Intersection Capacity Utilization (ICU) methodology to evaluate AM and PM peak hour LOS at signalized intersections. The latest version of the Highway Capacity Manual (HCM) methodology will be used to evaluate AM and PM peak hour LOS at unsignalized intersections. Peak hour is identified as the highest one-hour period in both AM and PM counted periods, determined by four consecutive 15-minute count intervals.
ICU Methodology
- Minimum clearance interval of 0.10 of green time
- Lane capacities of 1,800 vehicles per hour per lane for through and turn lanes
- Lane capacities of 3,240 vehicles per hour for dual turn lanes
HCM Methodology
- Observed peak hour factor (PHF) for existing conditions
- PHF of 0.95 for future conditions
Pedestrian activity should be considered on a case-by-case basis using reductions in saturation flow rates for affected lanes as determined by sound engineering judgment. The HCM provides guidance for assessing pedestrian influences on flow rates.
Analysis Scenarios
The following analysis scenarios should be evaluated for LOS analysis (at the discretion of the City Traffic Engineer):
- Existing Conditions: Data collected within the previous 2-year period.
- Opening Year: Existing traffic plus ambient growth and traffic from all developments within the study area that have submitted applications or been approved but not yet constructed. Multiple opening years may be required for phased projects.
- Opening Year plus Project: Existing traffic plus ambient growth, approved and pending developments, and traffic generated by the proposed project.
Phased projects will require interim year future analysis to address each phase and its associated traffic effects, with years to be analyzed approved by the City Engineer or designee.
A table summarizing forecast LOS for each intersection within the defined study area should be included, presenting LOS for all evaluated scenarios, including improvements.
Transportation Effects
The target LOS for intersections in the City is D or better, as established in the City’s General Plan. Any intersection operating at LOS E or F is considered deficient.
For signalized intersections, non-CEQA thresholds for volume-to-capacity (V/C) ratio are met if:
- The project-related increase in V/C is equal to or greater than 0.020 at an intersection that degrades from LOS D or better to LOS E or F.
For unsignalized intersections, non-CEQA thresholds for LOS are met if both of the following conditions are met:
- The addition of project traffic degrades overall intersection operations from LOS D or better to LOS E or F.
- The project-related increase in traffic contributes 10 percent or more to the total peak hour volume at an intersection already at LOS F.
On-Site Parking Analysis
This analysis will address on-site parking supply versus City code requirements. For mixed-use developments, a table should present each land use, its size, and the code parking requirement, clearly indicating how the code parking was calculated and showing the proposed on-site parking supply and the resultant surplus or deficit.
If the on-site parking supply is less than required by City code, a detailed explanation justifying a reduction must be included, noting that this does not eliminate the need for any zoning code variance. Shared parking evaluations will be considered when appropriate.
Access and Circulation Analysis
The project’s effect on access points and on-site circulation shall be analyzed, including:
- Number of access points proposed
- Spacing between driveways and intersections
- Potential signalization of driveways
- On-site stacking distance (including drive-thrus)
- Shared access
- Turn conflicts/restrictions
- Adequate sight distance
- Driveway improvements
- Pedestrian connections
- Other operational characteristics identified by City staff
For residential or commercial projects with privacy gates, the applicant shall provide a stacking analysis for review and approval. The interface with the arterial network must be demonstrated to be adequate, and necessary improvements to adjacent intersections may be required.
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