NREL OpenPATH

Name: NREL OpenPATH
Author: National Renewable Energy Laboratory

National Renewable Energy Laboratory

PROVEN

Validated with strong research evidence · Supported by multiple studies

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App Summary

NREL OpenPATH is an open-source research platform that uses a smartphone app to automatically log an individual's travel diary—including mode, energy use, and carbon footprint—to help communities and agencies study multimodal transportation patterns. A longitudinal study that used the app to analyze over 61,000 trips from low-income households found that participants provided with e-bikes most often replaced car trips (34% of e-bike trips). The associated research concludes that these findings demonstrate a considerable potential for energy savings and emissions reductions, highlighting how such data can support policies for sustainable and equitable transportation.

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Detailed Description

Functionality & Mechanism

Developed by the National Renewable Energy Laboratory (NREL), NREL OpenPATH is an open-source data collection platform functioning as an automatically sensed travel diary. The system leverages smartphone GPS and accelerometer sensors for continuous, passive trip detection. To conserve battery, the system deactivates GPS tracking when stationary. Following enrollment and consent within a specific study, the interface captures trip data and may prompt users to provide semantic labels for travel mode and purpose, which are configurable by researchers.

Evidence & Research Context

A validation study assessing the platform's mode inference algorithms demonstrated weighted F1 scores of 0.74 (Android) and 0.60 (iOS) and identified a systemic under-counting of trip length.
An integrated machine learning model designed to reduce user labeling burden was found to predict trip purpose, mode, and replaced mode with 72-81% accuracy in a longitudinal study.
The platform has been utilized as a primary data collection tool in transportation research, including a preliminary e-bike adoption pilot study (N=12) and a subsequent large-scale program.
Data collected via the app in an e-bike adoption program indicated that e-bikes replaced personal car trips in 34% of instances among low-income households.

Intended Use & Scope

This platform is intended for transportation researchers, program administrators, and public planning agencies to conduct longitudinal travel behavior studies. Its primary utility is the collection of granular, multimodal trip data to evaluate mobility programs and inform policy. The system is not a consumer navigation or travel-planning tool; data accuracy is contingent on algorithmic performance and participant engagement.

Studies & Publications

11 publications

Peer-reviewed research associated with this app.

Development/Design Paper

OpenPATH - Leveraging Technology to Measure Travel Behavior

Wheelis et al. (2024) · NREL Research Hub

Describes the research-driven development of this app

Shifting transportation to more sustainable modes is a key piece of the decarbonization puzzle. However, mobility behavior and travel patterns are difficult to influence because they are difficult to measure. OpenPATH provides a tool to capture longitudinal behaviors through a smartphone application. Agencies interested in gathering data about a population's travel behavior can set up a deployment of the app customized to the needs of their community. Partners can choose between simple mode and purpose labels or surveys for each trip to balance the level of user engagement with the associated burden. The labels, trip surveys, and an initial demographic survey can all be tailored to the specific context of the deployment. The OpenPATH tool is unique in its open-source nature, ability to gather detailed longitudinal travel data, and design allowing direct engagement with travelers. A valuable technological advancement, this tool enables partners to measure the way changes in the transportation landscape impact their community. The suite of tools includes both public and administrator dashboards. The public dashboard supports continuous data analysis through charts presenting trip information updated daily. The administrator dashboard displays geospatial data and supports data export. Example applications have included e-bike programs; gathering valuable metrics on increased access to opportunities and reduction in VMT, and studies aimed at understanding existing mobility behavior to see where advancements such as electric vehicles could fit into these habits. OpenPATH collects travel data in association with an initial demographic survey, enabling detailed insight into the behavior patterns or impact of a certain program on different populations.

Development/Design Paper

Understanding Mobility Behavior Using OpenPATH

Duvall et al. (2023) · CDOT TDM Conference

Describes the research-driven development of this app

In this presentation, we present the motivation behind the creation of NRELOpenPATH, what data the tool can collect, how the app works, and how interested parties can set up a deployment for their own project. OpenPATH is unique in it's ability to engage users in longitudinal travel diary collection with a smartphone app. The app allows projects to examine the modes of users travel, as well as the purpose of that travel. Many deployments have examined the way users travel by e-bike, and the app supports data collection across all modes to gain a holistic view of mobility behavior. The app is configurable for each deployment, and we will describe the way in which NREL hosts project deployments of our open-source project. As this presentation is a part of a panel, time for questions will be included.

In the Media

NREL's Open-Source Vehicle and Mobility Tools Offer Routes to Reduce Transportation Energy Use, Emissions

NREL developed OpenPATH as part of its suite of open-source transportation tools to reduce energy use and emissions by allowing users to customize scenarios for route optimization and measuring personal carbon footprints by travel mode. "Open-source availability of these transportation tools allows users to explore and customize scenarios as they consider how to implement energy efficiency advancements into their processes," said NREL's Jake Holden, a senior decarbonized vehicle systems researcher. The tools provide a common framework for automakers, regulators, and research entities to share and validate transportation efficiency work.

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Small But Mighty: Electric Bicycles Can Bridge the Gap in Access to Transportation

NREL developed OpenPath to collect holistic travel data for understanding e-bike adoption and access, using the tool as part of Colorado's Can Do Colorado e-Bike Pilot program. The laboratory's OpenPath tool was critical to informing insights from the nation's largest e-bike program, which distributed about 200 e-bikes and 50 e-bike-share memberships to low-income essential workers across Colorado over nearly two years. NREL researchers found that participants generally preferred to walk distances up to one mile and use e-bikes for distances between one and four miles.

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Small But Mighty: Electric Bicycles Can Bridge the Gap in Access to Transportation

The Colorado Energy Office teamed up with NREL to understand how to increase e-bike adoption through the Can Do Colorado e-Bike Pilot, using NREL's OpenPATH tool to collect holistic travel data. The nearly two-year pilot distributed about 200 e-bikes and 50 e-bike-share memberships to low-income essential workers across Colorado, making it "the nation's largest e-bike program." Results show that e-bikes can serve unmet transportation needs while providing cost-effective alternatives with benefits including free parking and reduced traffic congestion.

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NREL OpenPATH Tool Enables Expanded E-Bike Pilot Program To Demonstrate Energy-Efficiency Benefits

The National Renewable Energy Laboratory (NREL) developed OpenPATH to collect and analyze travel data for Colorado's expanded e-bike pilot program, using a modular, open-source platform that automatically detects participant trips through a smartphone app. The platform "automatically detects participant trips through a smartphone app, creates a travel diary, and displays it to participants for labeling" to understand e-bike use patterns and evaluate carbon emissions savings. NREL made OpenPATH broadly available to public agencies, with program managers able to direct participants to install the app from Google Play or Apple app stores.

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Pilot Program Sheds Light on E-Bike Use Patterns, Energy-Efficiency Benefits

NREL partnered with the Colorado Energy Office to assess travel behavior impacts of providing low-income essential workers with e-bikes during COVID-19, using a smartphone platform called e-mission for data collection. Analysis results showed that e-bikes became the dominant travel mode for 30% of trips among participants, followed by shared rides at 29% and single-occupancy vehicles at just 20%. The initial three-month pilot with 13 Denver-area workers launched in fall 2020 and is informing a full-scale, two-year pilot across Colorado.

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