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What is a Traffic Impact Study? What is a Traffic Impact Analysis?

Let’s break down what a traffic impact study (TIS) is and why a traffic impact analysis (TIA) is essential for weighing the potential consequences of developments on roadway infrastructure.

Need to properly plan for traffic during & after your project is complete?

A traffic impact study (TIS) or analysis (TIA) is what you should likely consider. A Traffic Impact Analysis (TIA) is typically conducted by a traffic engineer and forecasts additional traffic associated with a proposed development, identifies potential problems that might influence traffic flow, and suggests ways to mitigate any negative effects.

This crucial study enables developers to ensure they plan accordingly and provide adequate access for the traveling public—an increasingly critical key to success in today’s urban environments.

Developments that are properly planned and designed with minimizing impacts to existing roadways in mind, while also providing safe and efficient access for all users are crucial to the health of a community.

tia blog

How do I know if my development will require a traffic impact study?

Understanding when and why you need a traffic impact study is an important step in the development process.

The level of required study will vary depending on the size and type of development, as well as the local laws and regulations in place. For example, in some states, such as California, cities and counties may require a TIA before approving certain projects. In other states, such as Virginia, specific regulations have been established to guide the review process for a TIA.

Local municipalities may request a Transportation Impact Study (TIS) if a new development is projected to cause 100 or more additional peak-hour trips. The TIS calculations are based on the Institute of Transportation Engineers’ Trip Generation Manual, which offers precise trip estimates for numerous land use types.

Who conducts a traffic impact study?Traffic impact analysis

Qualified and certified traffic consultants are the only ones able to accurately assess the impact of development projects on existing traffic conditions. As such, many local governments require a Professional Traffic Operations Engineer (PTOE) with demonstrated expertise in conducting TIS evaluations; these professionals collaborate closely with government officials throughout each study process.

Although it is rarely done, some agencies may choose for their own staff members to arrange studies conducted by outside experts in lieu of hiring directly.

What does a Traffic Impact Study cost?

The cost of a Traffic Impact Study will depend on the scope of work and complexity of the project. Factors that may affect pricing include the size and nature of the development, the availability of existing data, and any special considerations or requests from local government agencies. On average though, TIS evaluations typically range from $10,000 to $30.

When conducting a TIS or TIA, engineers typically evaluate factors such as:

  • Roadway capacity
  • Intersection operations
  • Pedestrian safety
  • Bicycle facilities
  • Parking needs 
  • Environmental impacts

They also must consider how the proposed development will affect existing transportation networks by analyzing the current traffic patterns of the surrounding roadways and factoring in any future growth projections.

Based on their findings, they can then recommend solutions to address any potential issues orTraffic Impact Analysis suggest ways to improve existing infrastructure in order to better accommodate the increased traffic demand from the new development.

Overall, traffic impact studies are essential for ensuring that new developments are properly planned and designed in order to minimize their impact on existing roadways while providing safe and efficient access for all users.

By understanding what a TIS or TIA is and why it’s important for traffic mitigation, developers can make sure they’re taking all necessary steps to ensure their project is successful and meets all local and state requirements.

WGI’s Traffic Engineers specialize in Traffic Impact Analysis (TIA), traffic planning, and assisting state and local government agencies to overcome the challenges of growth, environmental responsibility, and smart mobility.

Do you have questions about how many multifamily units, homes, or how much commercial square footage will trigger a Traffic Study? WGI can help!

Contact our expert team of engineers, design professionals, and consultants today, and put your project on the path to success. 

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