Traffic Impact Assessments: Data Collection Best Practices
Urban expansion, infrastructure development, and land-use changes all depend on precise traffic data. At the heart of this is the Traffic Impact Assessment (TIA)—a vital study to evaluate how a proposed development will affect local traffic conditions. For the results of a TIA to be credible, the data collection process must be robust, timely, and relevant. In this blog, we explore best practices in data collection to ensure that Traffic Impact Assessments provide reliable guidance for stakeholders.
What is a Traffic Impact Assessment (TIA)?
A Traffic Impact Assessment is a comprehensive study conducted before the construction or approval of a new project (such as a shopping mall, residential complex, or office building). It evaluates how the proposed development might affect current and future traffic patterns and whether the surrounding infrastructure can handle additional demand.
Why Accurate Data Collection is Crucial
The accuracy of any TIA depends on the quality of data collected. Poor data can lead to:
Underestimation or overestimation of future traffic volumes.
Misguided infrastructure investments.
Safety risks due to overlooked congestion points.
Delays in project approval or rejection by authorities.
Best Practices for Data Collection in TIAs
1. Identify Key Study Intersections and Road Links
Start by identifying intersections and corridors that are most likely to be affected by the development. Include:
Access points to the site.
Nearby arterial and collector roads.
Signalized and unsignalized intersections.
2. Conduct Peak Hour Traffic Counts
Ensure that traffic counts are conducted during peak periods, typically:
Morning (7:00 AM – 10:00 AM)
Evening (4:00 PM – 7:00 PM)
Weekend counts if applicable (for retail or recreational developments)
Use Turning Movement Counts (TMCs) at intersections to capture entry, exit, and through movements.
Related Service: Turning Movement Counts Analysis
3. Include Multi-Modal Traffic Data
Modern TIAs must include data on:
Pedestrians
Bicycles
Public transit
Trucks and heavy vehicles
This gives a more holistic view of travel behavior and network performance.
4. Leverage Video-Based and Automated Data Collection
Use video surveillance and automated systems like pneumatic tubes or radar sensors to ensure consistent, accurate results. This also reduces human error in manual counting.
5. Factor in Seasonal and Temporal Variations
Avoid collecting data on holidays, school breaks, or unusual weather days. Where feasible, normalize data to account for seasonal trends using historical traffic volumes.
6. Coordinate with Local Guidelines and Standards
Different municipalities and regions have their own TIA guidelines. Always check for:
Study area limits
Required analysis scenarios (e.g., existing, background, and future conditions)
Thresholds for mitigation
7. Use Appropriate Software for Analysis
Input data into recognized traffic simulation or modeling tools such as:
Synchro
VISSIM
SIDRA
These tools help assess Level of Service (LOS), queuing, delay, and intersection performance.
Common Pitfalls to Avoid
Using outdated or irrelevant traffic data.
Ignoring non-motorized road users.
Incomplete study area coverage.
Not calibrating traffic models with local data.
Failing to document assumptions and methodologies.
Conclusion
High-quality data collection is the backbone of any successful Traffic Impact Assessment. By applying these best practices, urban planners, engineers, and developers can ensure that their TIAs are accurate, defendable, and compliant with local standards—resulting in smarter infrastructure and smoother project approvals.
If you’re looking for professional assistance in collecting and analyzing traffic data for your next development, Traffic Data Count offers comprehensive services tailored to TIA requirements.
