Without adequate transportation access, families can struggle to accomplish daily activities and be forced to trade expensive commutes for other needs and goods. Limited transportation access can also restrict opportunities for work and education. Evidence suggests that living in proximity to a bus or subway stop or having frequent transit services is associated with lower levels of unemployment, limited access to public transit is associated with higher levels of unemployment, and greater access to public transit reduces the likelihood of a household being on public assistance. Evidence indicates that living in neighborhoods far from jobs and without affordable transportation options undermines employment and economic success.
Metric: Transit trips index
This metric reflects the number of public transit trips taken annually at the census tract by a three-person single-parent family with income at 50 percent of the area median income for renters. This number is percentile ranked nationally into an index with values ranging from 0 to 100 for each census tract. Higher scores reflect better access to public transportation.
Validity: This metric was designed in partnership with the US Department of Transportation and has been used by the US Department of Housing and Urban Development in community efforts to affirmatively further fair housing. Several scholars have also used this metric and data in peer-reviewed journals. Although other arrangements of family composition, income, and housing status are possible in constructing this index and are available in the data, these characteristics were intended to more closely characterize a lower-income household in the community and are the most validated of other household combinations.
Availability: The estimates come from the location affordability index, which is publicly available.
Frequency: The location affordability index data are updated every three years.
Geography: This metric can be measured at the census tract or neighborhood level. Values can be averaged at higher levels of geography. For example, one can calculate a population-weighted average value among all census tracts in a county to determine a county-level value.
Consistency: This metric can be calculated the same way over time.
Subgroups: This metric is based on a lower-income population, notably single-parent families earning half the local area median income among renters. This metric can also be disaggregated by subarea when used in combination with the ACS to identify the racial or ethnic composition of neighborhoods (census tracts) with different levels of access. We distinguish census tracts that are majority nonwhite, that have no majority race or ethnicity, and that are majority non-Hispanic white. We define a majority as at least 60 percent of residents.
Limitations: This metric cannot alone capture the concept of transportation access. This must be used in partnership with the low transportation cost index to cover geographies that may not have an extensive public transportation system, such as rural areas.
Metric: Low transportation cost index
This index reflects local transportation costs as a share of renters’ incomes. It accounts for both transit and cars. This index is based on estimates of transportation costs for a three-person, single-parent family with income at 50 percent of the median income for renters for the region (i.e., a core-based statistical area). Although other arrangements of family composition, income, and housing status are possible in constructing this index, these characteristics were intended to more closely characterize a lower-income household in the community. Values are inverted and percentile ranked nationally, with values ranging from 0 to 100. The higher the value, the lower the cost of transportation in that neighborhood.
Validity: This metric was designed in partnership with the US Department of Transportation and has been used by the US Department of Housing and Urban Development in community efforts to affirmatively further fair housing. Several scholars have also used this metric and data in peer-reviewed journals.
Availability: The estimates come from the location affordability index, which are publicly available.
Frequency: The location affordability index data are updated every three years.
Geography: This metric can be measured at the census tract or neighborhood level. Values can be averaged at higher levels of geography. For example, one can calculate a population-weighted average value among all census tracts in a county to determine a county-level value.
Consistency: This metric can be calculated the same way over time.
Subgroups: This metric is based on a lower-income population, notably single-parent families earning half the local area median income among renters. This metric can also be disaggregated by subarea when used in combination with the ACS to identify the racial or ethnic composition of neighborhoods (census tracts) with different levels of access. We distinguish census tracts that are majority nonwhite, that have no majority race or ethnicity, and that are majority non-Hispanic white. We define a majority as at least 60 percent of residents.
Limitations: Transportation costs may be low for a variety of reasons, including greater access to public transportation and the density of homes, services, and jobs in the neighborhood and surrounding community. It is important consider this metric not by itself but rather in combination with the transit trips index to more fully measure the concept of transportation access.
