Housing + Transportation Affordability Index
About
History
The Housing + Transportation (H+T®) Affordability Index was developed by the Center for Neighborhood Technology (CNT) and its collaborative partner, the Center for Transit Oriented Development (CTOD), as a project of the Brookings Institution's Urban Markets Initiative.
The first phase was released in January 2006 and specifically examined the variables that inform housing and transportation costs in St. Paul/ Minneapolis, MN. The key finding of this report is that location matters, and it can affect the true cost of housing when transportation costs are factored in. For more information see The Affordability Index: A New Tool for Measuring the True Affordability of a Housing Choice.
The initial H+T Index research found that two primary independent variables in the household transportation model—residential density and household income—drive three primary dependent variables: auto ownership, auto use and transit ridership. For a general description of the methodology used to develop the H+T Index click here.
The initial Index received much attention from policy makers for its benefits to planners and transit-oriented development (TOD) advocates, and it served as the basis for several additional research projects.
In 2006 the Center for Housing Policy published A Heavy Load: The Combined Housing and Transportation Burdens of Working Families using H+T Index data compiled by CNT for working families in 28 metros.
In early 2008, CNT expanded the H+T Index to include neighborhood-level data for 52 U.S. metropolitan areas, again with support from the Brookings Institution. This effort resulted in an interactive mapping website where users could see H+T Index results at the neighborhood level, with additional information on auto ownership, transit use, housing density and other community characteristics. Also in 2008, CNT co-authored, with Carrie Makarewicz, a doctoral candidate at the University of California at Berkley, the report Estimating Transportation Costs by Characteristics of Neighborhood and Household, published by the Transportation Research Record: Journal of the Transportation Research Board.
At the height of the gasoline price peaks in the summer of 2008, CNT added maps for the 52 metros on the H+T Index website, showing how rising gasoline prices adversely affected vulnerable auto-dependent neighborhoods.
In 2009, in partnership with the Urban Land Institute's Terwilliger Center for Workforce Housing and the Center for Housing Policy (CHP), CNT produced an updated H+T Index analysis for the Washington, D.C. area, culminating in Beltway Burden : The Combined Cost of Housing and Transportation in the Greater Washington, DC, Metropolitan Area. To expand the reach of the H+T Index, CNT developed a new online housing and transportation cost calculator where consumers can access up-to-date Washington, D.C. cost data to make informed housing decisions. CNT later partnered with ULI and CHP to produce Bay Area Burden: Examining the Impacts and Hidden Costs of Housing and Transportation and added the San Francisco region to the online cost calculator.
In 2009, a new greenhouse gas analysis was included on the website, providing two views of urban greenhouse gas emissions associated with household auto use.
The latest H+T Index release in March 2010 expands the analysis to 337 metros in the United States, providing coverage for more than 80% of the U.S. population.
CNT is currently working to expand and update the H+T Index with 2005-2009 American Community Survey 5-Year Estimates data at the Census block group level. Other model components will be investigated, including separating transportation costs for renters and owners and improving auto cost data. CNT is also collecting a uniform dataset of stops and frequencies for transit agencies in all U.S. metropolitan and micropolitan regions for use in the Index. As part of this process, CNT will invite an academic advisory committee to provide feedback on statistical methods and practices, document the results of the latest research on the H+T Index website, and submit the updated model to a peer-reviewed journal.
Throughout the evolution of the H+T Index model, the key finding remains the same: household transportation costs are highly correlated with urban environment characteristics, when controlling for household characteristics.
By quantifying the average transportation costs for households based on location, the H+T Index provides a more holistic and accurate view of the true cost of housing. The H+T Index data have implications for consumers, planners, and policy makers. Potential policy applications of the Index are discussed more fully in the CNT report, Penny Wise Pound Fuelish.
CNT thanks its funders for their insightful and generous support for the development and expansion of the H+T Index: The Brookings Urban Markets Initiative, Center for Housing Policy of the National Housing Conference, Chicago Community Trust, The Energy Foundation, The Ford Foundation, Grand Victoria Foundation, The Joyce Foundation, John D. and Catherine T. MacArthur Foundation, McKnight Foundation, Nathan Cummings Foundation, Rockefeller Foundation, Searle Funds at the Chicago Community Trust, Surdna Foundation and Wallace Global Fund.
The H+T Index has also been greatly enhanced by the many transit agencies who generously shared their route and system information with CNT.