Requirements for Completing a Transportation Impact Assessment (TIA)
2.1 Need to Complete a TIA The County may require a Transportation Impact Assessment (TIA) for any development application under the Planning Act, such as:
- Official Plan Amendments and Secondary Plans,
- Zoning By-law Amendments,
- Draft Plans of Subdivision and Condominium, and
- Site Plans.
Criteria for Requiring a TIA: The need for a TIA is based on:
- Trip Generation: the anticipated traffic volume from the proposed development,
- Location: specific conditions of the subject land,
- Operational or Safety Concerns: issues related to the road network.
To assess if a TIA is required, the first step is estimating the projected travel demand generated by the proposed development. Trip generation thresholds help determine the level of TIA required:
Trip Generation Thresholds (Table 2.1):
- 0 – 25 vehicle trips per hour (vph): No TIA required,
- 25 – 100 vph: Traffic Impact Brief and Safety Plan,
- Over 100 vph: Comprehensive Transportation Impact Study.
Even if a development does not exceed the 100 vph threshold, a Comprehensive TIA may still be required if location or safety criteria are met. A TIA could be triggered by:
- Developments in areas designated for intense development,
- Proposals that may require new traffic control measures,
- Developments with drive-through facilities, or
- Developments that serve as regional destinations (e.g., recreation, entertainment).
Operational or Safety Concerns that may trigger a TIA:
- Roadway speeds exceeding 80 km/h,
- Limited sight distances,
- Significant traffic delays, long queues, or nearing capacity,
- Driveways within 200 meters of signalized intersections,
- Proximity to high truck traffic or intersections.
If none of the criteria are met, no TIA is required. The applicant is encouraged to confirm the need for a TIA with the County before starting the process.
2.2 Scope of Work for a TIA The scope of a TIA is outlined in the Scoping Checklist (Table 2.2) and should be confirmed with the County before commencing. The two types of TIAs are:
- Traffic Impact Brief and Safety Plan: for developments generating between 25 and 100 vph,
- Comprehensive Transportation Impact Study: for developments generating over 100 vph.
If required elements are not provided, the County may consider the TIA incomplete.
2.3 Requirements of Other Jurisdictions In addition to County requirements, consultation with local municipalities, adjacent municipalities, and/or the Ministry of Transportation (MTO) is recommended if the development impacts roads under their control.
2.4 Tools and Methods The County accepts the following for intersection analysis:
- Highway Capacity Software (HCS),
- Synchro (HCM-based),
- Microsimulation software (e.g., Vissim, Paramics, SimTraffic),
- Roundabout software (e.g., Rodel, Arcady, Sidra).
The latest versions should be used, and assumptions must align with County standards.
2.5 Documentation and Reporting The TIA report should include a main document and technical appendices with detailed assumptions and analysis methods. Key assumptions regarding lane configurations, traffic control devices, and trip generation should be thoroughly documented.
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