Transportation Planning

Traffic Impact Analysis (TIA)

What is a TIA?

York County has experienced a high growth rate in recent years, resulting in significant increases in traffic volume that affect the entire transportation network.  A Traffic Impact Analysis (TIA) is one tool York County employs to ensure development impacts are properly mitigated through the construction or funding of improvements at adversely affected intersections. Planning staff uses a TIA to make informed decisions about a proposed development's trip generation and the mitigation that may be required to address the project's impacts to the network's existing level of service.

When is a TIA required?

A traffic impact analysis is required as part of most development applications (rezoning, site plan, preliminary plat, and special exception) where a proposed project is expected to generate a significant number of trips. There are two levels of analysis, or tiers, for a Traffic Impact Analysis. A Tier 1 TIA is appropriate for developments that are expected to generate a low volume of traffic at the site, while a Tier 2 TIA is appropriate for developments that are expected to generate a high volume of traffic at the site. Please contact Planning staff to learn more about TIA requirements and which tier of analysis your project will require.

Who completes a TIA? 

A traffic impact analysis is typically completed by a traffic engineering firm at the expense of the applicant. York County does not complete a Traffic Impact Analysis on the behalf of an applicant. York County is also not able to make any recommendations on which traffic engineering firm to use for the completion of a traffic impact analysis.

Further Information

• Traffic Impact Analysis Guidelines (PDF)
• TIA Preliminary Site Evaluation Form (PDF)
• Transportation Corridor Overlay Guide (PDF)