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Person Miles Traveled By Mode

Indicator Description

Person miles traveled by mode measures the amount that the average person either 1) walks in a year or 2) drives in a year in private vehicles, including cars, vans, sport utility vehicles, pickup tricks, taxicabs, other trucks, recreational vehicles, motorcycles, and light electric vehicles such as golf carts. Data come from the 2009 National Household Travel Survey (NHTS). If more than one person travels together on a trip, each person is considered as making one person trip with associated person miles traveled.

Related Strategies

Transportation and Health Connection

Examining person miles traveled by mode is a useful tool for understanding the relationship between travel patterns and health outcomes. This indicator provides information about all trips and their distances, which neither the commute mode share nor vehicle miles traveled (VMT) per capita captures. From a transportation perspective, increasing person miles traveled by active transportation modes (i.e., walking or bicycling) could help reduce emissions, congestion and travel costs; from a public health perspective, this increase could impact positively health outcomes associated with increased physical activity and could impact injury rates across modes. In contrast, traveling in a motor vehicle is sedentary behavior, which does not achieve these beneficial outcomes.  In the cross-sectional Coronary Artery Risk Development of Young Adults (CARDIA) study, walking or bicycling to work was associated with increased fitness level and decreased obesity and blood pressure (Gordon-Larsen, et. al., 2009). Active transportation, either by walking or bicycling, to neighborhood amenities has been associated with lower levels of obesity and increased levels of fitness (Boone-Heinonen, et. al., 2009). In fact, research has shown that active transportation is associated with lower levels of self-reported obesity and diabetes in all 50 states and 47 of the 50 largest U.S. cities (Pucher, Buehler, Bassett, Dannenberg, 2010). Overall, there is a significant 12% reduction in mortality associated with active transportation (Samitz, et al., 2011), and there is an 11% reduction in risk of cardiovascular disease associated with active transportation (Hamer, et. al., 2008 and Hu, et. a., 2007.

Additionally, motor vehicle travel contributes to air pollutant emissions, which affect air quality and several associated health outcomes. Exposure to traffic-related air pollution is strongly linked with adverse health outcomes, including cardiovascular, asthma, and respiratory symptoms (Health Effects Institute, 2010). One study showed that by choosing a low-traffic bicycle boulevard, cyclists can reduce their exposure to vehicle-related air pollution (Jarjour et al., 2013). Transportation also accounts for 28% of the total greenhouse gas emissions in the United States, the second largest contributor (U.S. EPA, 2013). As VMT increases, so do emissions.

About the Data

The NHTS, conducted by the U.S. Department of Transportation, is a national survey that collects demographic, economic, and daily trip-related data from a sampling of U.S. households to inventory travel patterns. Through the NHTS online Table Designer tool, data for annual million person miles by transportation mode can be downloaded for each state. The estimated number of households in each state is also available through the NHTS. Households participating in the survey keep travel diaries for one 24-hour period.

A limited number of households participate in the NHTS survey. Therefore, sampling errors are a limitation of the survey (U.S. DOT, Federal Highway Administration, 2011). Previous travel surveys were conducted in 1969, 1977, 1983, 1990, 1995, and 2001. The time between surveys limits the use of this data source for tracking longitudinal changes or trends.

Moving Forward

Transportation decision makers can use information on person miles traveled by mode to evaluate and explore different ways to change the built environment to yield positive effects on physical activity, air quality, and health. Data on person miles traveled by mode might reflect changes in transportation system user preferences over time and could indicate how newly implemented active transportation policies and built environment changes influence or shift travel behaviors.

References

Boone-Heinonen J, Jacobs DR, Sidney S, Sternfeld B, Lewis CE, Gordon-Larsen P. A walk (or cycle) to the park: active transit to neighborhood amenities, the CARDIA study. American Journal of Preventive Medicine 2009;37:285-92. http://www.ajpmonline.org/article/S0749-3797%2809%2900411-5/abstract. *

Gordon-Larsen P, Boone-Heinonen J, Sidney S, Sternfeld B, Jacobs DR, Lewis CE. Active commuting and cardiovascular disease risk: the CARDIA study. Archives of Internal Medicine 2009;169:1216-23. http://archinte.jamanetwork.com/article.aspx?articleid=773531.

Hamer M, Chida Y. Active commuting and cardiovascular risk: a meta-analytic review. Preventive Medicine 2008;46:9–13.

Health Effects Institute. Traffic-Related Air Pollution: A Critical Review of the Literature on Emissions, Exposure, and Health Effects; 2010. http://pubs.healtheffects.org/getfile.php?u=552. *

Hu G, Jousilahti P, Antikainen R, Tuomilehto J. Occupational, commuting, and leisure-time physical activity in relation to cardiovascular mortality among Finnish subjects with hypertension. American Journal of Hypertension 2007;20(12):1242-1250.

Jarjour S, Jerrett M, de Nazelle A, Hanning C, Daly L, Lipsitt J, Balmes J. Cyclist choice, traffic-related air pollution, and lung function: a scripted exposure study. Environmental Health 2013;12:14. http://www.ehjournal.net/content/12/1/14. *

Pucher J, Buehler R, Bassett DR, Dannenberg, AL. Walking and cycling to health: A comparative analysis of city, state, and international data. American Journal of Public Health 2010;100:1986-1992. http://ajph.aphapublications.org/doi/abs/10.2105/AJPH.2009.189324.

Samitz G, Egger M, Zwahlen M. Domains of physical activity and all-cause mortality: systematic review and dose-response meta-analysis of cohort studies. International Journal of Epidemiology 2011;40(5):1382–1400.

U.S. Department of Transportation Federal Highway Administration. Summary of Travel Trends: 2009 National Household Travel Survey; 2011. http://nhts.ornl.gov/2009/pub/stt.pdf.

U.S. Department of Transportation. National Household Travel Survey (NHTS); 2011. http://www.rita.dot.gov/bts/help_with_data/national_household_travel_survey.html.

U.S. Environmental Protection Agency. Inventory of U.S. Greenhouse Gas Emissions and Sinks; 2013:1990-2011. http://www.epa.gov/climatechange/Downloads/ghgemissions/US-GHG-Inventory-2013-Main-Text.pdf.

* Indicates research that supports policies analyzed

† Indicates research that supports equity or vulnerable populations studied

Last updated: Monday, August 24, 2015