A Traffic Impact Analysis (TIA) provides information on the projected traffic expected from a proposed development. A TIA also evaluates the impact of proposed development on the roadways in the immediate proximity of the proposed development. The TIA should identify any potential traffic operational problems or concerns and recommend appropriate actions to address such problems or concerns. 

A traffic impact analysis shall be consistent with the code requirements and the Transportation Criteria Manual. The geographic area to be considered in the TIA shall be established by the Director. The TIA should consider and account for the potential traffic to be generated by other undeveloped sites within the established study boundaries.

A neighborhood traffic analysis is a simplified TIA that assesses the impact of a proposed project on residential streets. A neighborhood TIA is limited to an evaluation of existing and projected operating levels of residential streets and an identification of mitigation measures needed to minimize traffic impacts.

TIA requirements apply to each individual lot when an application is made to zone or rezone the lot or for site plan approval to develop the lot.

Generally modifications to an application may include but are not limited to:

  1. A reduction in the number of projected vehicle trips per day.
  2. Dedication of additional right-of-way.
  3. Rerouting of traffic and of proposed access and egress points serving the proposed project;
  4. Participation in the funding of traffic signal and /or intersection improvements.

Vehicle Trip Thresholds A local or collector street means any roadway not designated as an arterial street. A residential local or collector street is one along which 50% or more of the frontage within 1,500 feet of the proposed project's property lines (or the nearest arterial, whichever distance is less) is zoned SF-5 or more restrictive uses.

  • A TIA is required if the expected number of trips generated by the project exceeds 2,000 vehicle trips per day.
  • A neighborhood traffic analysis is required if the project has access only to a residential local or collector street and the expected number of vehicle trips generated by the project exceeds 300 vehicle trips per day over the existing uses.