Transportation+Choices


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=**Transportation Choices: Journey to Work and Vehicle Miles Traveled**=

**Journey to Work**
 The means people choose to travel to work is a standard measure examined by the US Census American Community Survey. To travel to work, commuters may drive alone, carpool, take public transit, bike or walk. We report the proportion of Triangle workers that use each of these means to travel to work for the period 2006-2008.
 * What is this?**

 The type of transportation people choose can have a significant affect on the environment. Driving personal vehicles contributes disproportionatetly to air pollution and greenhouse gas emissions as compared to transit, walking, or biking. Air quality is important for human health and for sensitive ecosystems.
 * Why is this important?**

Interstate 40 just west of Raleigh.


 * **// A Few Driving Facts //**

Americans own 2.3 vehicles per household on average. Owning a second car costs $8,100 per year on average. The Triangle is the in the top 20 metro areas for unhealthy air days. In the US, New York City has the highest public transit ridership to work: 55%. Average percentage of US workers who take transit to work: 5 %.

**Sources**: // Wake Up Wake County // []; // The New York Times // []; //US Census FactFinder// [] ||

 During the period 2006-2008, 76% of Triangle workers drove alone to work; 14% carpooled and 2% used public transit (Figure 1). Orange County had the lowest proportion of workers who drove alone to work (67%) and the highest proportion using transit (7%) (Figure 2).
 * What does this measure show?**


 * Figure 1. ** Proportion of Triangle workers, age 16 and older, using various modes of transportation to travel to work, 2006-2008.


 * Figure 2. ** Proportion of workers, aged 16 and older, using various modes of transportation to travel to work, shown by county, 2006-2008.

**Vehicle Miles Travelled**

 * What is this?**

Vehicle miles traveled - often denoted VMT - is another way to measure how much driving is ocurring in a region. It is a common transportation measure of the total number of miles driven by all vehicles in a given area. It can be measured per county, per person, or per region. A commonly used statistic for a region is //daily vehicle miles travelled per person// (which you are likely to see abbreviated in technical reports as DVMT). We report the average daily vehicle miles travelled per person in each county and for the Triangle as a whole in 2006.

 The transportation sector accounted for 33% of greenhouse gas emissions in the US in 2007 ([]). Vehicles contribute to climate change, which has important health, economic, and environmental impacts. Although vehicles are a key component of commerce and transportation, finding alternative forms of travel may be more healthful and environmental on many levels. Availability of alternatives to expensive single-occupied vehicles is important for a vibrant economy, cleaner air, and healthier people.
 * Why is this important?**

 As shown in Figure 3, in 2006, Wake County had the lowest average daily vehicle miles travelled per person, at 30.5, with Durham close behind at 33.5; Johnston County had the highest at 44.9 miles. Average daily vehicle miles traveled per person is a reflection of land use patterns and transportation policies. The choices that are available to residents can shape behavior, which in turn impacts the environment. For example, Johnston County's high value likely reflects long commutes to Raleigh and Research Triangle Park by people who moved to Johnston in response to highway access to relatively inexpensive housing. These results have important implications for regional planning policy (see// Reality Check information // in the Introduction to this section).
 * What does this measure show?**



 The survey does not distinguish personal and commercial vehicle miles travelled, and includes all vehicle types, so actual mileage per personal vehicle may be lower. In addition, the vehicle miles travelled estimates are based on traffic counts which may or may not represent a perfect sample of a day’s worth of driving for that county. Traffic counts observe all traffic including through-traffic, not only vehicles driven by county residents or workers.
 * Limitations**


 * Author** Amanda Campbell, University of North Carolina-Chapel Hill :: 2010 April 28
 * Reviewers** Emily Ander, City of Raleigh :: Walter Thurman, NC State University


 * Technical Notes**


 * //Journey to Work//**

This measure is based on residents’ answers to a question that is a consistent part of the American Community Survey estimates, reported for years 2006-2008 for each county. Each resident in the household surveyed is asked to respond to this question:

How did this person usually get to work LAST WEEK? If this person usually used more than one method of transportation during the trip, mark (X) the box of the one used for most of the distance.

Car, truck, or van ||| Bus or trolley bus ||| Streetcar or trolley car ||| Subway or elevated ||| Railroad Ferryboat ||| Taxicab ||| Motorcycle ||| Bicycle ||| Walked ||| Worked at home ||| Other method

Error rates vary from less than 0.5% to 3% depending on sample size. These are indicators that are reasonably reliable and are commonly used as indicators of travel choices. However, the journey to work is only one part of a resident’s travel habits. Travel to school, the grocery store, retail, and other services are also important in determining amount of air pollution emitted or avoided. This spreadsheet contains more information:[|Journey to Work.xlsx].

Source: [] Choose: Economic Characteristics—Commuting to Work


 * //Vehicle Miles Traveled//**

Population aged 16 years and older was derived from American Community Survey estimates from the US Census for the year that the traffic counts were taken. Since the census provides ages in categories, one spanning 15 to 19, 4/5ths of this category was allocated to 16-19. This calculation assumes that there are the same number of residents of each age. Vehicle miles traveled data were taken from North Carolina Department of Transportation data for 2006 contained here: [|NC VMT_G - HPMS data 2007(1).XLS], using the most recent data for which actual counts, rather than projections, were available. This spreadsheet contains more information on how the measure was calculated : [|CensusDataVMT.xlsx].

**//References//**

NC Geographic Information Coordinating Council. NC one map. N.d. [cited February 10 2010]. Available from@http://www.nconemap.com.libproxy.lib.unc.edu/.

Noor, M. 2008. Many families limiting themselves to a single car. //New York Times//, July 28, 2008.@http://www.nytimes.com.libproxy.lib.unc.edu/2008/07/27/nyregion/nyregionspecial2/27Ronecar.html?_r=1&ref=nyregionspecial2 (accessed April 7, 2010).

U.S. Census Bureau. American factfinder. N.d. [cited April 1 2010]. Available from@http://factfinder.census.gov.libproxy.lib.unc.edu/home/saff/main.html?_lang=en.


 * Connecting People with Nature Indicators**
 * //Parks & Nature Recreation//** :: Natural Area Recreation :: Proximity to Parks
 * //Environmental Education//** :: Environmental Education Centers :: Community Colleges :: State Curriculum
 * //Environmental Choices//** :: Green Buildings :: Transportation Choices :: Waste and Recycling Practices