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Public Transportation System: Introduction or Expansion

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What is the public transportation system?

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Public transportation systems include a variety of transit options such as buses, light rail, and subways. These systems are available to the general public, may require a fare, and run at scheduled times. The purpose of introducing or expanding public transportation is to increase access to and use of public transit while, at the same time, reducing motor vehicle miles driven and  traffic congestion.[1]

Public transportation systems are often implemented at the local or regional level and can be supported by federal initiatives, such as the Fixing America’s Surface Transportation (FAST) Act. [1, 2]  Los Angeles County is one example of a region that expanded its public transportation system using local, state, and federal funding.[3, 4]

What is the public health issue?

Transportation systems help ensure that people can reach everyday destinations, such as jobs, schools, healthy food outlets and healthcare facilities, safely and reliably.[5] Public transportation services play an important role for people who are unable to drive, including those without access to personal vehicles, children, individuals with disabilities, and older adults.[5] The U.S. transportation infrastructure focuses on motor vehicle travel (e.g., passenger cars, vans, SUVs, pickup trucks, and other light trucks) and provides limited support for other transportation options.[6, 7] According to the U.S. Census Bureau, in 2013 approximately 86 percent of all workers traveled to work by private vehicle, and 76 percent drove alone.[8] Also in 2013, 69 percent of urban households and 14 percent of rural households had access to public transit.[4] Although using public transportation has historically been safer than travel in passenger vehicles, passenger vehicle travel has grown more quickly than other modes of travel.[1,7,9] Motor vehicle crashes continue to be the leading cause of injury-related death for many age groups.[7,10] In 2013, motor vehicle crashes were the second leading cause of death among individuals aged 13 to 25 years.[11]

Public transportation systems provide opportunities for increased physical activity in the form of walking or biking on either end of the trip (e.g., from home to bus stop or from train stop to office) and reduced motor vehicle travel.[12-14] Despite these benefits, many Americans view walking and bicycling within their communities unfavorably because of barriers such as disability, age, chronic disease, inconvenience or safety concerns about traffic and a lack of sidewalks, crosswalks, and bicycle facilities.[7,15] Physical activity and active transportation (e.g., biking and walking) declined compared to previous generations; the lack of physical activity contributes to obesity, diabetes, heart disease, stroke, and other chronic health conditions in the U.S.[7,15]

Air pollution from motor vehicles continues to contribute to adverse respiratory and cardiovascular health effects.[7,16] Nitrogen oxides and volatile organic compounds react with sunlight to create ozone.[17] Carbon monoxide, nitrogen oxides, and ozone are associated with a variety of health problems including myocardial ischemia, chest pain, coughing, throat irritation, and airway inflammation, and can worsen bronchitis, emphysema, and asthma.[18-20] Particulate matter, which is produced by engine exhaust and tire and brake wear, is associated with an increased risk of respiratory and cardiovascular disease.[21-22]

What is the evidence of health impact and cost effectiveness?

Public transportation systems are associated with reductions in several health risk factors such as motor vehicle crashes, air pollution, and physical inactivity. The U.S. Department of Transportation reported that public transportation (school, intercity, transit bus, light rail transit, and subway) accounted for less than one percent of transportation fatalities in 2011, while private passenger vehicles accounted for more than 75 percent of transportation fatalities.[1, 23] An analysis of the transportation fatality risk in the U.S. found that the fatality rates per billion passenger miles traveled between 2000 and 2009 were 0.11 for buses, 0.24 for urban mass transit rail trains, 0.43 for passengers on commuter rails, and 7.28 for drivers or passengers in a car or light truck.[24] For every passenger mile traveled, public transportation produces only a fraction of the harmful pollution of private vehicles: only five percent as much carbon monoxide, less than eight percent as many volatile organic compounds, and nearly half as much carbon dioxide and nitrogen oxides.[25]

A systematic review examining public transportation use and physical activity found that use of public transport was associated with an additional 8 to 33 minutes of walking per day.[26] A study of the impact of adding light rail stations in Los Angeles found it to be associated with an increase in daily physical activity among residents with previously lower physical activity levels.[27] The expansion was also associated with a reduction in vehicle miles traveled and their related emissions.[27] Another study found that train commuters took an average of 30 percent more steps per day than car commuters.[28] A study of 130 U.S. cities found that each rail passenger mile represents a reduction of three to six automobile passenger miles—through direct substitution and indirectly through the creation of compact, mixed-use transit-oriented developments that foster walking and cycling and reduced automobile ownership.[29]

A descriptive cost analysis examined the value of the health benefits, which included fewer traffic crashes, less air pollution and increased physical fitness, of increasing the proportion of the population that has access to public transit. The analysis estimated that if a city with a typical quality North American public transit service improved to high quality (i.e., fast, convenient and comfortable) urban rail or bus rapid transit service, the per capita annual health benefits would be $355. If improvements were made to achieve a high quality transit service with walkable, mixed-use development around stations, the per capita annual health benefits would be $541. It also estimated that for a city with a million residents, an increase in the proportion of households located in transit-oriented developments from 10 percent to 20 percent would produce nearly $71 million of total annual health benefits, and an increase from 10 percent to 40 percent would generate more than $216 million of total annual health benefits.[30]

A cost-benefit analysis that examined the impact of expanding public transportation capacity by converting a lane for bus rapid transit found an association with positive net benefits to society, including travel time savings, travel cost savings, and emissions reduction. [31]

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  1. County Health Rankings & Roadmaps, Public transportation: system introduction or expansion. 2014 September 16 [cited 2015 November 25]; Available: Public transportation: system introduction or expansion.
  2. The Federal Transportation Act: The Fixing America’s Surface Transportation (FAST) Act. 2015: U.S.
  3. Metro. Transportation Funding. Project, Programs and Plans 2016 [cited 2016 June 15]; Available from: Transportation Funding.
  4. American Society of Civil Engineers, 2013 Report Card for America’s Infrastructure Findings. 2013. Available from: 2013 Report Card for America’s Infrastructure Findings
  5. U.S. Department of Transportation, Connectivity: Relationship to Public Health. 2015 [cited 2016 July 18]; Available: Connectivity: Relationship to Public Health.
  6. National Highway Traffic Safety Administration, Traffic Safety Facts: 2012 Data, U.S. Department of Transportation, Editor. 2014. Available from: Traffic Safety Facts: 2012 Data
  7. Centers for Disease Control and Prevention, CDC Transportation Recommendations. 2010 [cited 2016 June 15]; Available: CDC Transportation Recommendations .
  8. McKenzie, B., Who Drives to Work? Commuting by Automobile in the United States: 2013, U.S. Department of Commerce Economics and Statistics Administration, U.S. Census Bureau, Editor. 2015, American Community Survey Reports: Washington, DC. Available from: Who Drives to Work? Commuting by Automobile in the United States: 2013
  9. U.S. Department of Transportation, Federal Transit Administration, About FTA – History. n.d. [cited 14 April 2017]; Available:
  10. Centers for Disease Control and Prevention, National Center for Injury Prevention and Control. Ten Leading Causes of Death and Injury, Web-based Injury Statistics Query and Reporting System (WISQARS) [online]. 2005 [cited 2017 April 14]. Available:
  11. Xu, J. et al., Division of Vital Statistics, Deaths: Final Data for 2013, in National Vital Statistics Reports. 2016, National Center for Health Statistics, Vol 64 No 2: Hyattsville, MD. Available from: Deaths: Final Data for 2013
  12. Besser, L.M. and A.L. Dannenberg, Walking to public transit: steps to help meet physical activity recommendations. American journal of preventive medicine, 2005. 29(4): p. 273-280.
  13. Miller, H.J., et al., Public transit generates new physical activity: evidence from individual GPS and accelerometer data before and after light rail construction in a neighborhood of Salt Lake City, Utah, USA. Health & place, 2015. 36: p. 8-17.
  14. Brown, B.B., et al., Transit use, physical activity, and body mass index changes: objective measures associated with complete street light-rail construction. American journal of public health, 2015. 105(7): p. 1468-1474.
  15. U.S. Department of Health and Human Services, Step It Up! The Surgeon General’s Call to Action to Promote Walking and Walkable Communities. 2015, U.S. Dept of Health and Human Services, Office of the Surgeon General; Washington, DC [cited 2017 April 14]. Available:
  16. Caiazzo, F., et al., Air pollution and early deaths in the United States. Part I: Quantifying the impact of major sectors in 2005. Atmospheric Environment, 2013. 79: p. 198-208.
  17. U.S. Environmental Protection Agency, Ozone Pollution. 2016 May 18 [cited 2016 June 27]; Available: Ozone Pollution.
  18. U.S. Environmental Protection Agency, Ozone Basics: Effects on Health and the Environment. 2016 May [cited 2016 June 27]; Available: Ozone Basics: Effects on Health and the Environment.
  19. U.S. Environmental Protection Agency, Carbon Monoxide: Health. 2016 February [cited 2016 June 27]; Available: Carbon Monoxide: Health.
  20. U.S. Environmental Protection Agency, Nitrogen Dioxide: Health. 2016 February [cited 2016 June 27]; Available: Nitrogen Dioxide: Health.
  21. Hung-Lung, C. and H. Yao-Sheng, Particulate matter emissions from on-road vehicles in a freeway tunnel study. Atmospheric Environment, 2009. 43(26): p. 4014-4022.
  22. Anderson, J.O., J.G. Thundiyil, and A. Stolbach, Clearing the air: a review of the effects of particulate matter air pollution on human health. Journal of Medical Toxicology, 2012. 8(2): p. 166-175.
  23. U.S. Department of Transportation, Bureau of Transportation Statistics, Tranportation Fatalities. National Transportation Statistics 2016 [cited 2016 June 15]; Available: Tranportation Fatalities.
  24. Savage, I., Comparing the fatality risks in United States transportation across modes and over time. Research in Transportation Economics, 2013. 43(1): p. 9-22.
  25. Shapiro, R.J., K.A. Hassett, and F.S. Arnold, Conserving energy and preserving the environment: The role of public transportation. American Public Transportation Association, 2002.
  26. Rissel, C., et al., Physical activity associated with public transport use—a review and modelling of potential benefits. International journal of environmental research and public health, 2012. 9(7): p. 2454-2478.
  27. Boarnet, M.G., et al., The Exposition Light Rail Line Study: a Before and After Study of the Impact of New Light Rail Transit Service. 2013: The Haynes Foundation: Los Angeles, CA.
  28. Wener, R.E. and G.W. Evans, A morning stroll levels of physical activity in car and mass transit commuting. Environment and Behavior, 2007. 39(1): p. 62-74.
  29. Litman, T., Impacts of Rail Transit on the Performance of a Transportation System. Transportation Research Record: Journal of the Transportation Research Board, 2005(1930): p. 21-29. Available from: Impacts of Rail Transit on the Performance of a Transportation System
  30. Litman, T., Evaluating Public Transportation Health Benefits. 2010, Victoria Transport Policy Institute. Available from: Evaluating Public Transportation Health Benefits
  31. Ang-Olson, J. and A. Mahendra, Cost/benefit Analysis of Converting a Lane for Bus Rapid Transit: Phase II Evaluation and Methodology. 2011: Transportation Research Board.