Building confidence in traffic data: The development of Expansion Factors

For the Altitude team, our journey is driven by a commitment to providing the best possible insights to our customers. We understand that data, while valuable, is only as useful as the insights it generates. This principle guided us through developing the updated Expansion Factors 3.0 model and supporting modeled AADT counts, which are significant upgrades to our Altitude platform. This story isn’t just about technical advancements—it’s about how we listened to our customers, responded to their needs and improved our tools to better serve them.

Listening to our customers

Our journey began with listening. Version 2 of Expansion Factors had already set a foundation for providing valuable traffic data, but we knew there was room for improvement. Customers frequently shared their challenges and needs with us, highlighting the necessity for more granular and accurate data. They needed insights they could trust, derived from transparent methodologies, and applicable to critical planning and decision-making processes.

Recognizing the gaps

In Version 2, we used TMAS (Travel Monitoring and Analysis System) data and FHWA’s (Federal Highway Administration counting stations as our primary data sources. While this provided a solid foundation, the limitations became clear. We had approximately 14,000 directional stations, which, while significant, were not enough to offer the comprehensive insights our customers needed for detailed traffic analysis. The expansion factors were limited, and customers wanted a broader scope, encompassing various vehicle types and more precise traffic patterns.

Building a transparent methodology

Transparency has always been a cornerstone of our approach. Understanding the importance of this to our customers reinforced the need for meticulous documentation of our data collection, processing, and expansion methodologies. Our commitment to clarity ensures that every step is transparent, allowing customers to see exactly how we achieve our market-representative numbers. This dedication to openness builds the trust and reliability that our customers expect.

Figure 1: Example of improved coverage in Texas. V 2.0 discrete locations (Red) vs V 3.0 continuous segments (blue).

Recognizing these gaps, we embarked on a transformative journey. Expansion Factors 3.0 with AADT (Annual Average Daily Traffic) is the latest upgrade to the Altitude platform, offering unmatched model transparency for trustworthy volume estimates . Version 3 introduces a completely new approach to calculating traffic data, transitioning from FHWA counting stations to HPMS (Highway Performance Monitoring System) AADT data, and expanding to eight million road segment edges. This significant increase enhances granularity, accuracy and confidence, making the data highly useful for statistical analysis, traffic trends and market insights.

The new model enhances HPMS AADT data to support use cases that require a comprehensive understanding of total vehicle population and traffic volume, where sampled data alone is not adequate. By changing our approach to focus on road segments, we provide more accurate and comprehensive insights into traffic patterns. By pulling data from the full network for AADT (motorway, trunk, primary, secondary and tertiary) instead of discrete locations, we reduced sampling bias, noise and outlier bias. The new model reports by road type and creates five AADT models, one per road type, each with its own R², improving the reliability and precision of the data.

“Incorporating HPMS AADT data into our models has significantly enhanced their accuracy. The increased number of sampling points allows for a more detailed and precise analysis, leading to better-informed decisions and more reliable expansion factor estimates.”
– Kasra Azizbaigi, Senior Data Scientist

Figure 2: Expansion Factors 3.0 is built on modeled AADT which has an average R² of 0.902 across all supported road types, allowing us to provide accurate traffic volume expansion across county-level road segments in the United States.

With our expanded data set and transparent methodology, we focused on enhancing data integrity. Reliability starts from the source, and Altitude is that source, with data from over four million commercial vehicles. This allows us to offer detailed insights into vehicle type, vocation and class. By using source vehicle data, we provide greater context, including vehicle types, vocations and industry tracking over time. This comprehensive approach offers insights not possible with third-party data sources, enabling our customers to rely on data that truly represents real-world road conditions.

“When planning for infrastructure, we understand the importance of having accurate and comprehensive data. With access to over 4 million commercial vehicles, Altitude’s insights not only meet these needs but also provide rich contextual information that is unmatched in the market.”
– Shweta Shah, AVP, Product & Engineering

We designed Expansion Factors 3.0 to meet the diverse needs of our customers and partners. This version offers enhanced granularity and precise data, essential for a wide range of applications. City planners can model traffic flow changes, highway authorities can adjust traffic policies, and developers can plan commercial real estate projects with confidence. The improved granularity supports high-confidence vehicle estimates for projects like parking analysis, infrastructure development, congestion management and safety projects.

• Support Freight Planning: Gain access to accurate information, enabling informed planning decisions. This enhanced capability is supported by granular traffic volume data across various road types, including Motorway, Primary, Secondary, Tertiary, and Trunk segments.
• Precision Site Selection: Make informed decisions based on where your ideal customers will be, not just areas with high traffic. This is achieved by breaking down traffic volumes into market-representative heavy, medium and all commercial and non-commercial vehicles.
• Alternative Fuels and Charging: Verify that decisions regarding biodiesel, electric, ethanol, hydrogen and other alternative fuel infrastructure are made for maximum use. Analyze truck dwell times and range to choose optimal sites for charging and refueling depots with context beyond vehicle miles and distance traveled (VMT/ VKT) data.
• Improve Road Safety: Identify high-risk areas and develop targeted safety interventions to construct safer and more efficient road networks. Reliably evaluate safety interventions and prioritize areas based on traffic volume.

Figure 3: A view of the Expansion Factors information provide in the overview view within Origin & Destination.  

Shaped by customer feedback, these updates provide transportation planners with accurate, granular traffic data. Our transparent methodology ensures you can trust the insights derived from our enhanced sampling techniques. Expansion Factors 3.0 is built with key features that offer unmatched detail and accuracy to meet our customers’ needs.

• County & State Expansion: Support for every state and the vast majority of counties in the U.S. allows for comprehensive coverage by applying county and state-level expansion factors. These factors can be applied to various zones at the user’s discretion, including City, TAZ, ZIP, CTR, and Custom Zones.
• Segmentable Traffic Volumes: Classifies vehicle volumes by heavy (class 7, 8), medium (class 3-6) and all commercial and non-commercial vehicles.
• Greater Road Granularity: Offers significantly more coverage than the previous model, providing detailed insights into Motorways, Primary, Trunk, Secondary and Tertiary road segments.
• Modeled AADT: Available through the Regional Travel Metrics module, this metric provides modeled road volume counts, saving users from expanding the estimates.