TRPA Project Impact Assessment (PIA) Tool for Vehicle Miles Traveled (VMT) Analysis and Mitigation
The Tahoe Regional Planning Agency (TRPA) has developed the Project Impact Assessment (PIA) Tool, a comprehensive analytical resource designed to assist in evaluating and mitigating vehicle miles traveled (VMT) impacts associated with development projects in the Lake Tahoe Basin. The PIA Tool serves multiple functions, including:
- Project Screening: Determining whether a project is exempt from further VMT analysis based on established criteria.
- VMT Analysis: Conducting VMT assessments for residential, tourist accommodation, and public service projects that do not meet exemption criteria.
- VMT Mitigation Identification: Identifying appropriate mitigation measures for projects that exceed established VMT significance thresholds.
- Mitigation Fee Calculation: Estimating the mobility mitigation fees required for projects contributing to increased VMT.
To ensure consistency in analysis, projects utilizing the PIA Tool must be generally aligned with the surrounding built environment in terms of land use type, density, mix of uses, and transit accessibility. TRPA staff must verify this consistency before the tool can be applied for analytical purposes. Notably, projects extending beyond the Lake Tahoe Basin boundaries are ineligible for analysis using the PIA Tool.
PIA Tool Functionality by Land Use Type
The table below outlines the applicability of the PIA Tool for different land use categories:
| Land Use | Determine Screening | Calculate Mobility Mitigation Fee | Conduct VMT Analysis |
|---|---|---|---|
| Residential | ✓ | ✓ | ✓ |
| Tourist Accommodation | ✓ | ✓ | ✓ |
| Commercial | ✓ | ◯ (Screened projects only) | ✗ |
| Public Service | ✓ | ✓ | ✓ |
| Recreation | ✓ | ◯ (Screened projects only) | ✗ |
| Transportation | ✗ | ✗ | ✗ |
| Other | ✗ | ✗ | ✗ |
(✓ = Available for all projects meeting eligibility criteria, ◯ = Available only for screened projects, ✗ = Not available)
VMT Estimation and Mitigation Measures
The PIA Tool calculates project-generated VMT based on land use type, project size, and location-specific data derived from the Tahoe Activity-Based (AB) Model. This data is essential for determining mobility mitigation fees and potential mitigation strategies.
To reduce project-related VMT, the PIA Tool also incorporates calculations for various VMT reduction strategies, including:
- Unbundling Parking Costs: Separating parking costs from property costs to encourage alternative transportation.
- Commute Trip Reduction Programs: Implementing voluntary or required measures to reduce commuter vehicle trips.
- End-of-Trip Facilities: Providing amenities such as bike lockers and showers to encourage non-motorized commuting.
- Shuttle Services: Establishing private or employee shuttles to reduce single-occupancy vehicle trips.
- Traffic Calming Measures: Implementing design strategies to promote safer, multimodal transportation options.
A detailed discussion of these mitigation measures is provided in Appendix D of the TRPA Project Impact Assessment Guidelines
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