Daily Transportation Indicators Explained
The Bureau of Transportation Statistics (BTS) prioritized resources to develop timely indicators to track transportation changes due to COVID-19. BTS partnered with the National Renewable Energy Laboratory (NREL) and the Department of Energy to access Vehicle Travel Trends from INRIX. BTS also partnered with the Maryland Transportation Institute and Center for Advanced Transportation Technology (CATT) Laboratory at the University of Maryland to estimate the Daily Travel data and number of people staying home and not staying home.
The data are experimental and may not meet all our quality standards. Experimental data products are created using new data sources or methodologies that benefit data users in the absence of other relevant products. We are seeking feedback from data users and stakeholders on the quality and usefulness of these new products. Experimental data products that meet our quality standards and demonstrate sufficient user demand may enter regular production if resources permit.
The two data sets (the INRIX Vehicle Travel Trends and UMD CATT lab Daily Travel data) are similar, but have several major differences. The table below highlights how the two data sets are different but related.
|Vehicle Travel Trends||Daily Travel|
|Source||INRIX||University of Maryland CATT Lab|
|Defined as||Exclusively vehicles on all public roads; breaks out passenger, local fleet, and long-haul trucks||All trips taken by any mode of transportation|
Seasonally adjusted and indexed trip count; trip distance; trip duration; and vehicle miles traveled
Percent of people staying at home; Population Staying at home; Population not staying at home; Total Trips; Trips < 1 mile; Trips 1-3 miles; Trips 3-5 miles; Trips 5-10 miles; Trips 10-25 miles; Trips 25-50 miles; Trips 50-100 miles; Trips 100-250 miles; Trips 250-500 miles; Trips 500+ miles
|Granularity||National and state level data as well as some international data||National, state, and county level data|
|Frequency||Daily data||Daily data|
|Measured:||Metrics are calculated from device/trip ID, location, heading, and speed from connected cars, mobile phones, local fleet reports, and long-haul truck transponders.||Metrics are calculated from a national mobile device data panel merged from multiple data sources that address the geographic and temporal sample variation issues often observed in a single data source. A weighting procedure expands the sample of millions of mobile devices, so the results are representative of the entire population in a nation, state, or county.|
|Timeline||Data updated weekly on Tuesday; the data lags 72 hours behind the current date and begins March 1, 2020.||Data updated weekly on Mondays; the data lags one week behind the current date and begins January 1, 2019.|
Trips are defined as movement of at least 200 meters in 10 minutes, if that criteria is not met the trip is ended. When movement starts again, a new trip record is created.
The seasonal adjustment mathematically adjusts the observed values to reflect changes due to seasonal trends.
To normalize the metrics, INRIX established a range of dates that would be considered “typical” travel behavior, not impacted by the pandemic. INRIX defined the baseline period as all non-holiday days between January 20 to February 28, 2020, inclusive. Using these dates, they computed the median trip count, distance traveled, trip duration, and average trip distance by day of week and created a ratio of the observed value and the median typical value for that measure for that day of week.
The index equal to 1.0, indicates pre-pandemic levels of travel as measured against the baseline. Values above 1 indicate more travel than the pre-pandemic baseline and values below 1 indicate less travel than the pre-pandemic baseline.
Trips are defined as movements that include a stay of longer than 10 minutes at an anonymized location away from home. A movement with multiple stays of longer than 10 minutes before returning home is counted as multiple trips.
Population staying at home is the number of residents who make no trips with a trip end more than one mile away from home.