TRB 2016 Blue Ribbon Committee
16th National Transportation Planning Applications Conference

Approaches to Evaluating VMT using GPS-based Probe Vehicle Data

Corresponding Author: Laura Schewel, StreetLight Data

Presented By: Laura Schewel , StreetLight Data, Inc.


Traffic flow, often measured as Level of Service (LOS), has traditionally been used as a primary indicator of performance and basis for project evaluation, but has significant recognized limitations. Vehicle Miles Traveled (VMT) reduction has been recognized as an important complementary measure for evaluating improvements, as measures that reduce VMT can provide more permanent congestion relief, reduce greenhouse and criteria gas emissions, and decrease wear and tear on roadways. VMT is typically estimated using methods such as petroleum use and surveys that are too general, and that no longer reflect today’s changing vehicle technology mix. In contrast, real-world GPS data enables planners to estimate the total volume and length of trips in virtually any size geography – from small municipalities to states to entire regions. To use VMT as a guide for policy and infrastructure decisions, more nuance and precision is required. Planners must be able to assess the causes behind changes in VMT, and to see how patterns change by geography, income, urban form, weather and more.

In his paper and presentation, Seth Golub will explore how Vehicle Miles Traveled (VMT) has become an increasingly viable, useful metric for transportation project prioritization. He will focus on the ways that Big Data from GPS-enabled mobile devices and connected cars can be used to evaluate VMT accurately and efficiently, and use real-world example case studies to illustrate the types of questions that VMT evaluations based on Big Data can answer for planners.

By analyzing VMT in three different types of zones (a TAZ, a region, and a state) using both traditional methods and Big Data based methods, Seth will demonstrate how planners can use GPS data to truly understand VMT, including assessing the causes behind changes in VMT. To provide transportation planners with a roadmap for using VMT calculations to evaluate projects in their own communities, Seth will evaluate sample projects for these regions using a Big Data-based VMT estimate and a traditional VMT estimate, then contrast the results. He will also explore changes in regional VMT over time; the contributions of particular areas, land use, and development types to regional VMT; the contributions of short personal and commercial trips to VMT, and the respective impact of internal trips and pass-through trips on VMT.


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