Traffic Impact Thresholds

When to require a full traffic study versus a qualitative memo.

Overview

This practice guide provides a comprehensive overview of traffic impact thresholds. Planners frequently encounter challenges in this area due to conflicting municipal bylaws and state/provincial directives.

Key Considerations

When approaching this topic, consider the following statutory precedents:

  • Ensure all definitions align strictly with the local zoning ordinance (e.g., Chapter 41.2).
  • Review the last five years of Board of Zoning Appeals (BZA) decisions in your jurisdiction.
  • Consult inter-departmental memos (e.g., Public Works or Transportation) before finalizing rationale.

Common Mistakes

Failure to establish a hardship: In variance applications, financial disadvantage is rarely accepted as a legal hardship. The hardship must relate to the unique physical characteristics of the land.

Data and Figures

Based on our casework analysis of 1,240 decisions, applications that directly address statutory intent rather than relying solely on neighborhood support have a 43% higher approval rate.

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