Traffic Intensity Overlay District: Managing Development Along Napa’s Key Corridors

City of Napa: :TI Overlay District – Summary and Interpretation

The :TI (Traffic Intensity) overlay district is a zoning tool used by the City of Napa to regulate land use intensity and manage traffic generation along key transportation corridors identified in the General Plan's Circulation Element. The purpose of this overlay is to ensure that development does not exceed acceptable traffic thresholds that would negatively impact crucial corridors already prone to congestion.

Purpose

The core intent of the :TI overlay is to implement crucial corridor policies outlined in the General Plan by:

1. Protecting traffic flow along designated corridors;

2. Regulating high-traffic land uses that could degrade corridor performance;

3. Establishing site design requirements to minimize traffic conflicts and improve circulation safety.

The overlay applies to the following major streets:

• Imola Avenue West (SR-121): Lernhart Street to Soscol Avenue

• Trancas Street: SR-29 to Soscol Avenue

• Lincoln Avenue: Jefferson Street to Silverado Trail

• Jefferson Street: Trancas Street to Imola Avenue West

• Soscol Avenue: Trancas Street to Imola Avenue West

• Silverado Trail: Trancas Street to Soscol Avenue

Applicability and Review

The :TI overlay can be applied to any base zoning district and supplements, rather than replaces, the base zoning regulations. Where conflicts exist, the more restrictive :TI provisions take precedence.

Prior to the approval of certain development actions, the Public Works Director must review the project for consistency with the :TI overlay. This includes:

• Establishment of new uses not requiring a building permit;

• Design review or building permit for new buildings or expansions exceeding 10% of gross floor area;

• Approval of conditional use permits where the use may affect traffic flow.

Application Process and Fees

Applicants must submit plans, specifications, and supporting information demonstrating compliance with the :TI overlay. A review fee may be charged, set by City Council resolution, to offset the cost of analyzing traffic impacts. The Public Works Director will typically respond within 30 days. Decisions may be appealed to the City Council.

High and Low Traffic-Generating Uses

Uses are classified based on their trip generation rates:

• Low Traffic-Generating Uses: Generate 520 or fewer trips per gross acre per day.

• High Traffic-Generating Uses: Exceed 520 trips per gross acre per day.

Trip generation is based on both proposed and existing uses on the site, including shared parking and driveways. These thresholds align with studies conducted by the Public Works Department and reflect typical development intensities.

Development Standards

Within the :TI overlay, the Public Works Director will review proposals against the following:

A. Crucial Corridor Policy Consistency

Projects must align with policies in the Circulation Element of the General Plan, which may include additional restrictions or allowances beyond the overlay.

B. High Traffic Uses

High traffic uses are generally prohibited unless:

• The project is modified (e.g., size, design, operations) to reduce trips below the 520-trip threshold; or

• The Public Works Director determines that the project's transportation benefits—such as road improvements, transit enhancements, or TDM strategies—outweigh the additional traffic impact.

Drive-through uses are discouraged but may be allowed through a use permit with additional findings demonstrating that traffic generated by the drive-through component does not significantly exceed that of the underlying use, and that any excess trip generation is offset by substantial transportation benefits.

C. Site Design to Minimize Conflicts

• Driveways must minimize direct access to crucial corridors. Side street access is preferred and may be required.

• Joint access and parking agreements between adjacent parcels are encouraged or may be mandated.

• In cases of inadequate on-site parking, the Public Works Director may require up to 20% more parking than typically required.

• On-site signage must meet city traffic control standards.

A waiver of these standards may be granted if existing site constraints render them unnecessary to meet the overlay’s objectives. Applicants must provide adequate justification to the Public Works Director.

Multiple Lots as One Site

Developers may apply to treat two or more abutting lots as a single site for traffic regulation purposes. This is done through a written agreement (e.g., cross-access easements), approved by the Public Works Director and recorded with the County. Once approved, lots must be evaluated as a single site and cannot be considered individually for future :TI compliance without a new application.

Existing Nonconforming Uses

Any use lawfully established before the adoption of the 1998 General Plan that exceeds the 520-trip threshold is considered a nonconforming use. These may continue as long as they do not increase their trip generation.

Traffic Study Requirements

If a proposed project is initially found to exceed allowable traffic levels, applicants may submit a trip generation study prepared by a qualified traffic engineer. The study must follow the Public Works Department’s Traffic Impact Analysis (TIA) Guidelines. Once reviewed and accepted, the study will be used to determine compliance with the overlay regulations.

Appeals

Applicants may appeal decisions made by the Public Works Director to the City Council. However, if the appeal involves disputing the trip generation rate of a project, a trip generation study (as outlined above) must be submitted along with the appeal.

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