Building confidence in traffic data: The development of Expansion Factors
Learn more about expansion factors with Geotab ITS and how they enable organizations to enhance their transportation networks.
Transportation planners are digging deep into traffic data in order to make informed decisions for their region’s infrastructure with the aim to create more efficient roadways.
That traffic data has traditionally been collected through either manual processes like mail-in surveys or increasingly through automated vehicle detection systems. The former suffers from low response rates and limited impact while the latter lacks a critical factor – context.
Without context, planners are left guessing as to why situations happened in the first place and cannot proactively plan for future incidents. More informed transportation planning decisions will require a deeper level of understanding context for traffic patterns and anomalies. One of those contextual factors that can play an integral part in aiding these decisions is vocation; understanding not just traffic volume but the vehicle’s purpose on the road. Vocation and other contextual insights are a key part of the Geotab ITS Altitude platform. Its data helps to provide critical answers for why vehicles are on the road in order to make informed decisions to support the overall flow of traffic and commercial freight activity.
THE CHALLENGE:
One of the primary purposes of SCAG’s transportation planning and policy recommendations is to promote the ongoing improvement of the goods movement system in Southern California. The importance of goods movement in the region cannot be overstated, considering it provides approximately one-third of the region’s jobs. As a leading global trade gateway to the U.S., Southern California is home to a high concentration of industries that depend on goods movement, such as manufacturing, construction, wholesale and retail trade, transportation and warehousing.
Freightworks, the SCAG Goods Movement Program, creates up-to-date information and tools to support a world-class goods movement system that relies on complex infrastructure ranging from marine ports and rail lines to local, state and interstate roads. Every four years, SCAG must also produce the Regional Transportation Plan/Sustainable Communities Strategy (RTP/SCS). It’s a massive undertaking that addresses all modes of Southern California’s transportation system, including goods movement. For every RTP cycle, SCAG must calibrate and validate the regional travel demand model based on the most recently observed, real-world data collected from a variety of sources including PeMS, Caltrans count book and Screenline count.
“No data set is perfect”, says SCAG transportation modeler Mana Sangkapichai. “We’re always working to increase the quality of input data to enhance the accuracy of our models. We’re also constantly calibrating and validating the model by comparing it with direct observations in the transportation system.”
The current Regional Transportation Plan was approved in 2020, and the plan forecasts out to 2045. With the next plan due in 2024, SCAG modelers are now busy refining the data inputs. “We’re starting to update the model and calibrate for the base year of 2019,” says Sangkapichai. “Once the base year model is validated, we can run the model for future years.”
One crucial category of data for transportation models specifies the aggregate journeys of large commercial vehicles: where they are coming from, where they’re going, how they’re traveling and why.
The rise of e-commerce in recent years and the resulting increase in delivery vehicle traffic has further complicated the task of collecting aggregate origin-destination data for the current planning cycle. “The type of delivery trucks that are called light-heavy are now having a much bigger impact on regional traffic,” he says. “This trend, along with the lack of data by vehicle weight classification, convinced us that we needed more consistent, high-quality origin-destination data for our models; data that was able to distinguish between vehicle classes.”
THE SOLUTION:
With the Origin & Destination product from the Geotab ITS Altitude platform, SCAG transportation modelers can access deeper insights into commercial vehicle and freight activity across the six counties and beyond. Origin & Destination combines Geotab’s leading connected-vehicle data with the power of Geotab ITS’s analytics to deliver both a micro and macro picture of vehicle journeys.
From vehicle purpose to aggregate route analysis, SCAG can zoom in and out of Geotab ITS’s underlying transportation data to:
“In our truck model, for example, we use federal data to determine the total Vehicle Miles Traveled (VMT), which is important information, but only at a very high level,” says Sangkapichai. “Combining existing data with Geotab ITS’ Altitude Origin & Destination delivers far more detail on these truck miles, from beginning to end, enriching our data sources.”
Altitude enables SCAG modelers to process months of data in minutes in order to:
“Before, we couldn’t access reliable data on vehicle weight classification,” says Sangkapichai. “With Altitude, we can now break down the percentage of light-, medium- and heavy-duty trucks using certain roads at certain times.”
THE RESULTS:
While SCAG’s Altitude implementation is still quite new, the modeling team sees significant current and future potential for the Altitude Origin & Destination product to update and improve its transportation models. “So far, we’re really impressed with the information Altitude is providing,” says Sangkapichai. “We’re excited to learn more about all that the platform can do as we move forward with additional training and demonstrations.”
For now, Sangkapichai and his team are focusing on incorporating the new insights on commercial vehicle journeys for calibrating their models. In the future, the team believes this information will help SCAG better identify:
“The movement of goods is a critical issue for transportation planners as they balance the demands of the boom in e-commerce and last-mile delivery,” says Sangkapichai. “Altitude’s Origin & Destination offers us an easy, efficient way to keep our models up to date on freight and delivery truck activity.”
SCAG plans to use the validated models to evaluate potential truck-related policies, such as:
“Our models are the basis for vital planning initiatives that support a healthy, sustainable region,” says Sangkapichai. “Altitude by Geotab insights are helping us to prepare modelling and data to support SCAG planners.”
Learn more about how Altitude’s Origin & Destination product can help agencies understand the true purpose of trips on their roads through comprehensive insights into aggregate freight activity.
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