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For projects that do not satisfy any of the screening criteria mentioned above, a VMT analysis is mandatory. This analysis will utilize the most reliable data available to inform estimates of trip generation and trip lengths for the project's intended uses. For land use plans, such as Specific Plans or General Plans, and projects involving residential, office, and retail developments, the VMT analysis can be carried out using the SCAG model. In contrast, for other project types, such as performing arts centers or special event venues, the VMT analysis should be tailored to assess the unique trip generation and trip length characteristics of the proposed uses.
In accordance with current practices, the VMT analysis must evaluate the potential impacts of the project under both existing and future cumulative conditions as follows:
Existing/Baseline Conditions: The project-generated VMT should be estimated based on the proposed land uses under existing conditions. This can be calculated using the SCAG regional travel demand model and should be reported as VMT per capita (for residential projects), VMT per employee (for office or employment-generating projects), or VMT per service population (for other land uses). For land use plans, either VMT per service population or Total VMT can be employed to assess potential impacts.
Cumulative Conditions: A less than significant impact under existing conditions will also indicate a less than significant cumulative impact, provided the project aligns with the SCAG RTP/SCS.
In some instances, the project's effect on VMT should be assessed under cumulative conditions to ascertain whether VMT in the study area would be higher or lower in the future with the project. This analysis is relevant for large planning efforts that may alter regional travel patterns. To evaluate the project's impact on VMT, the future year travel demand model should be updated to include the project and to determine if the Citywide VMT would increase. The applicant may opt to redistribute land use to ensure that both the “no project” and “with project” assessments maintain the same total land use controls for the City, especially if the project is significant enough to affect land use absorption elsewhere.
According to CEQA Guidelines Section 15064.7 on Thresholds of Significance, lead agencies are encouraged to develop and publish their own thresholds of significance. Under Section 15064.7(b), the City has the authority to adopt VMT thresholds through an ordinance, resolution, rule, or regulation, following a public review process supported by substantial evidence. The OPR’s Technical Advisory suggests a threshold of 15% below the regional average for identifying significant VMT impacts for land use projects and plans. This recommendation is grounded in research aimed at determining the VMT reduction necessary to assist the State in achieving its climate objectives. The California Air Resources Board has quantified the VMT reductions needed to meet the State's long-term climate goals, and OPR considers a reduction to 15% below existing conditions as a reasonable threshold for new development projects.
Guidance from OPR also applies to transportation projects. For roadway widening projects, a significant impact is identified if the project increases baseline VMT in the study area.
The VMT thresholds for projects and plans within the City of Lancaster are summarized in Table 6 below.
Table 6: VMT Thresholds of Significance
| Project Type | Threshold for Determination of Significant VMT Impact |
|---|---|
| Residential Project | Exceeds 15% below AVPA Baseline VMT for home-based VMT per capita |
| Employment (Commercial or Industrial) Project | Exceeds 15% below AVPA Baseline VMT for home-based work VMT per employee |
| Regional Retail Project | Results in a net increase in total VMT per service population compared to AVPA Baseline VMT |
| Mixed-Use Projects | Evaluate each land use component separately using the criteria above |
| Land Use Plans | Exceeds 15% below AVPA Baseline VMT for Total VMT per service population |
| Other land use types | Exceeds 15% below AVPA Baseline VMT. For unlisted land use types, the City will determine the appropriate VMT metric based on project characteristics. For projects generating job-related travel, employment-generating VMT (home-based work VMT per employee) can be compared to the baseline. For other projects, total VMT per service population can be compared to the AVPA baseline, or net changes in Total VMT can be estimated. |
| Transportation Projects | Results in an increase in VMT in the study area compared to baseline conditions |
For projects that impact VMT, it is crucial to identify and implement mitigation options to mitigate or reduce these impacts. Effective mitigation strategies are those that lower the number of single-occupant vehicles generated by the site. This can be achieved by modifying the proposed land uses or implementing Transportation Demand Management (TDM) strategies. TDM strategies are recognized as highly effective in mitigating VMT impacts. These strategies may include specific project site modifications, programming, and operational changes.
The effectiveness of the proposed TDM strategies is primarily based on research documented in the 2010 California Air Pollution Control Officers Association (CAPCOA) publication, "Quantifying Greenhouse Gas Mitigation Measures" (CAPCOA, 2010). CAPCOA provides methodologies based on preferred and alternative literature for each strategy. The following strategies represent some of the most effective options in areas like Lancaster, some of which are already being implemented in the City pursuant to its TDM ordinance.
Strategy Descriptions and VMT Impact:
| Strategy | Description | VMT Impact | CAPCOA VMT Reduction |
|---|---|---|---|
| Increase Density | Designing projects with increased densities, where permitted by the General Plan or Zoning Ordinance, reduces GHG emissions associated with traffic. | Minimizes trip numbers and lengths, offering more alternative transport options. | 0.8% - 30% |
| Increase Diversity of Urban and Suburban Developments (Mixed Use) | Incorporating mixed uses within projects or in the surrounding area minimizes trips. | Reduces trip numbers and lengths. | 9% - 30% |
| Increase Destination Accessibility | Measures the number of jobs or attractions reachable within a certain travel time; central locations have higher accessibility. | Reduces trip numbers and lengths. | 6.7% - 20% |
| Increase Transit Accessibility | Placing high-density projects near transit promotes its use. | Encourages transit use, reducing vehicle trips. | 0.5% - 24.6% |
| Provide Pedestrian Network Improvements | Creating a pedestrian access network encourages walking instead of driving, resulting in lower VMT. | Promotes walking within and to a project. | 0% - 2% |
| Implement a Neighborhood Electric Vehicle (NEV) Network | NEVs provide an alternative for short trips (up to 30 miles) on roads with speed limits of 35 MPH or lower. | Reduces trip lengths; electrification cuts GHG emissions. | 0.5% - 12.7% |
| Provide Traffic Calming Measures | Traffic calming promotes walking or biking instead of driving, decreasing VMT. | Enhances pedestrian/bicycle safety and encourages shorter trips. | 0.25% - 1% |
| Implement Car-Sharing Program | Offers on-demand access to a shared vehicle fleet, reducing vehicle ownership and household vehicle numbers. | Lowers the need for personal vehicle ownership. | 0.4% - 0.7% |
| Encourage Telecommuting and Alternative Work Schedules | Reduces commute trips through flexible schedules or compressed workweeks. | Reduces commute days and shifts travel outside peak times. | 0.07% - 5.5% |
| Commute Trip Reduction Programs | Encourages alternatives to single-occupancy vehicle trips through employer programs. | Promotes alternative commuting methods. | 1% - 6.2% |
| Limit Parking Supply | Adjusts parking requirements to support smart growth and alternative transportation. | Encourages alternative transport modes. | 5% - 12.5% |
| Unbundle Parking Costs from Property Cost | Requires separate costs for parking spaces, discouraging vehicle use. | Promotes alternative transport choices. | 2.6% - 13% |
| Implement Market-Price Public Parking | Prices on-street parking to deter spillover and encourage walking between destinations. | Promotes a "park once" behavior. | 2.8% - 5.5% |
Mitigation strategies must be customized to the specific characteristics of each project, and their effectiveness needs to be analyzed and documented as part of the environmental review process to ascertain whether impacts can be mitigated or if they remain significant and unavoidable. Given that research on TDM strategies continues to evolve, feasible mitigation measures should be assessed based on the best available data when a project is under consideration by the City.
Four projects in the City of Lancaster have been identified as “pilot projects” to illustrate the anticipated VMT analysis process. These pilot projects represent a range of development types that could be implemented in the City:
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