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VMT Assessment for Non-Screened Development in the City of Anaheim

VMT Assessment for Non-Screened Development in the City of Anaheim

For development projects that do not qualify for screening based on the City of Anaheim’s established criteria, a comprehensive Vehicle Miles Traveled (VMT) analysis is required. This analysis, conducted using the Orange County Transportation Analysis Model (OCTAM), is essential to determine whether a project has significant VMT impacts. The evaluation involves assessing both “project-generated VMT” and “project effect on VMT” within the designated Traffic Analysis Zone (TAZ) or TAZs associated with the project. The analysis is performed across four primary scenarios to capture baseline and future conditions, both with and without the project.

Key Scenarios for VMT Analysis

  1. Baseline Conditions: This scenario evaluates existing travel patterns and conditions based on OCTAM’s baseline model. It reflects the state of transportation infrastructure and travel behaviors at the time of the study.

  2. Baseline Plus Project: This scenario incorporates the proposed project’s land use into OCTAM’s baseline model. It assesses how the addition of the project alters travel patterns and VMT under current conditions.

  3. Cumulative No Project: This scenario projects future travel conditions without the proposed project. It aligns with OCTAM’s forecasts for long-term growth and planned transportation infrastructure within the study area.

  4. Cumulative Plus Project: This scenario integrates the proposed project’s land use into OCTAM’s future model runs. It examines the combined effects of the project and cumulative growth on VMT in the area.

Required Model Outputs

The VMT analysis should generate the following outputs:

  • Total VMT: This includes all vehicle trips and trip purposes (e.g., work, shopping, recreation). Total VMT is used as an input for air quality, greenhouse gas (GHG), and energy impact analyses.

  • VMT Per Service Population: This metric normalizes total VMT by dividing it by the combined population and employment within the study area. It is the preferred measure for transportation impact analysis under California Environmental Quality Act (CEQA) guidelines.

Types of VMT Analysis

For the “Baseline Plus Project” and “Cumulative Plus Project” scenarios, two distinct VMT calculations are required:

  1. Project-Generated VMT Per Service Population:

    • This measure calculates the VMT directly attributable to the project. It is extracted from the travel demand forecasting model by using the origin-destination trip matrix and multiplying it by the final assignment skims.

    • The resulting VMT per service population is compared against established benchmarks in the City of Anaheim’s thresholds of significance.

  2. Project Effect on VMT:

    • This analysis examines how the proposed project changes overall VMT on the transportation network. It compares citywide VMT per service population under “No Project” and “With Project” conditions to determine the broader impacts of the project.

    • Link-level VMT data within the City’s boundaries are extracted from OCTAM outputs for both scenarios to estimate the project’s effect.

Steps for Conducting the Analysis

  1. Define the Study Area:

    • Identify the TAZ or TAZs associated with the proposed project. These zones, defined within OCTAM, are geographic areas bounded by arterial streets or natural barriers. They represent homogenous travel behaviors.

  2. Run OCTAM Scenarios:

    • Input project-specific land use data into the OCTAM model for the “Baseline Plus Project” and “Cumulative Plus Project” scenarios.

    • Generate outputs for total VMT and VMT per service population under all four scenarios.

  3. Extract Project-Generated VMT:

    • Use the origin-destination trip matrix to isolate trips generated by the project. Multiply this matrix by assignment skims (travel cost factors such as time or distance) to calculate total project-generated VMT.

  4. Evaluate Project Effect on VMT:

    • Compare link-level VMT data for “No Project” and “With Project” conditions within the City’s boundaries. This analysis identifies how the project influences overall travel patterns.

  5. Analyze and Compare Results:

    • Assess the project’s VMT per service population against the City’s significance thresholds. Projects exceeding these thresholds may require mitigation measures.

Significance Thresholds and Benchmarks

The City of Anaheim’s thresholds of significance are informed by regional benchmarks and CEQA guidelines. A project’s VMT per service population must align with or fall below the thresholds to avoid a significant transportation impact. These thresholds are designed to promote sustainable development and reduce reliance on single-occupancy vehicles.

Use of VMT Data in Environmental Analysis

The outputs of the VMT analysis serve multiple purposes beyond transportation impact assessment:

  • Air Quality Analysis: Total VMT, disaggregated by speed bins, provides inputs for estimating vehicle emissions. This data is essential for evaluating compliance with air quality standards.

  • GHG Emissions Analysis: VMT data informs greenhouse gas emissions modeling, helping to determine a project’s contribution to climate change.

  • Energy Impact Analysis: Vehicle travel data is used to estimate energy consumption, supporting evaluations of a project’s energy efficiency.

Applicability of the CEQA Exemption Threshold

Certain small-scale projects may be exempt from detailed VMT analysis based on CEQA guidelines. For example, projects generating fewer than 110 daily vehicle trips are presumed to have a less than significant transportation impact. This threshold aligns with CEQA’s categorical exemption for existing facilities and minor additions to structures.

Importance of Accurate Modeling

The integrity of the VMT analysis relies on the accuracy and relevance of the data input into the OCTAM model. Analysts must:

  • Verify that project land use assumptions are consistent with the proposed development.

  • Use the most recent version of OCTAM to ensure alignment with updated regional transportation forecasts.

  • Exercise professional judgment when interpreting results, particularly in cases where unique project characteristics may influence travel behavior.

 By evaluating both project-generated VMT and the project’s effect on citywide travel patterns, the City can make informed decisions that align with state mandates and regional sustainability goals. Detailed methodologies and procedures for conducting VMT assessments are outlined in Attachment C of the City’s TIA Guidelines.

Our Services are available throughout City of Anaheim with Zipcodes 92816, 92817

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