COMMON ACRONYMS

TIA

COMMON STANDARDS OF PRACTICE

1. Institute of Traffic Engineers (ITE) guidelines
2. Ministry of Transportation guidelines
3. TIA is prepared by an Engineer with experience in Traffic and Transportation Engineering 4. TIA is signed and stamped by an Engineer licensed by the AHJ or the regulating body of the Province/ Country

DEFINITION

Traffic impact assessment (TIA) is technical analysis of traffic problems, level of service of roadways/ intersections, and transportation related safety issues on an existing area or for an expansion or for a proposed development.

WHY

The main purpose of a Traffic Impact Assessment is to identify any impacts on transportation infrastructure and propose solutions for approval/ implementation. Some scenarios are given below.
1. Assess the impacts of a proposed project/ new development/ redevelopment/ land rezonong on an existing transport network/ infrastructure
2. Assess the impacts of an increase in traffic/ additional trips on an existing transport network/ infrastructure
3. Identify reasonable solutions to address these impacts.
4. Addressing transportation-related issues associated with development proposals that may be of concern to neighbouring residents, businesses and property owners
Major impacts considered are adequacy, user safety and traffic efficiency which are mitigated by managing traffic, optimizing intersections, redesigning signals, managing mass transit, adding traffic lanes, making priority lanes etc. etc..

WHEN

Various municipalities or AHJs (Authorities having jurisdition) require that a TIA is conducted before starting any work that might impact the existing transportation infrastructure. Some scenarios are given below.
1. A new road is to be constructed which is not a part of the approved master plan or an existing road is to be widened, modified/ upgraded
2. A new intersection is to be constructed or an en existing intersection is modified/ upgraded
3. A new subdivision is proposed to be developed
4. A rezoning is proposed
5. The expected number of vehicle trips generated by the project exceeds "X" vehicle trips per day, where "X" is specified by the AHJ. Some AHJs may still ask for an abbreviated TIA even if expected trips are lesser than the specified threshold "X". An abbrevaited TIA focuses only on the base year traffic conditions with and without the development. Full TIA, more suitable for larger changes/ impacts, analyzes both base and horizon year traffic conditions with and without the development.
6. The existing TIA has exceeded its shelf life (which is normally 5 years in many jurisdictions)
7. A new or modified access is proposed to connect to exisitng transportation infrastructure

HOW

Various AHJs issue guidelines for preparing the TIA, so that there is a consitency in how data is prepared and submitted. In general, a TIA Report shall have the following minimum contents.
1. Executive Summary
2. Proposed Development
3. Existing Conditions
4. Projections
5. Design Basis
6. Proposed Solutions
7. Conclusion
8. Glossary
9. Appendices/ Exhibits