Non-linear influences of the built environment on transportation emissions: Focusing on densities

Jinhyun Hong


Compact development is often recommended to reduce auto-dependency thereby decreasing related energy consumptions and transportation emissions. However, there could be a non-linear relationship between density and transportation emissions because of a possible non-linear association between density and vehicle miles travelled (VMT); low travel speed due to congestion; and the relationship between neighborhood characteristics and vehicle characteristics (e.g., vehicle type and age). In addition, the self-selection issue can exist in the land use-transportation emissions analysis because transportation emissions are often estimated based on travel behavior. Using the 2006 Puget Sound Regional Council (PSRC) Household Activity survey, the follow-up stated preference survey, the Motor Vehicle Emission Simulator (MOVES) data, and the GIS network data, this study investigates the non-linear effects of densities on CO2 equivalent (CO2e) emissions with the consideration of self-selection. Specifically, quadratic forms of population and employment densities, different population density group indicators, and attitudinal factors are employed in the regression models. The results indicate that people living in denser neighborhoods tend to generate fewer CO2e emissions. However, this effect becomes insignificant as population density reaches a certain level.


Transportation emissions, densities, non-linearity, self-selection

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Barla, P, Miranda-Moreno, L.F, Savard-Duquet, N, Theriault, M, & Lee-Gosselin, M. (2010). Disaggregated empirical analysis of determinants of urban travel greenhouse gas emissions. Transportation Research Board, 2156, 160-169.

Bento, A.M, Cropper, M.L, Mobarak, A. M, & Vinha, K. (2005). The effects of urban spatial structure on travel demand in the United States. The Review of Economics and Statistics, 87(3), 466-478.

Boarnet, M.G, & Crane, R. (2001). The influence of land use on travel behavior: Specification and estimation strategies. Transportation Research Part A, 35(9), 823-845.

Brownstone, D, & Golob, T.F. (2009). The impact of residential density on vehicle usage and energy consumption. Journal of Urban Economics, 65, 91-98.

Cao, X, Handy, S, & Mokhtarian, P. (2006). The influences of the built environment and residential self-selection on pedestrian behavior: evidence from Austin, TX. Transportation, 33, 1-20.

Cao, X, Xu, Z, & Fan, Y (2010). Exploring the connections among residential location, self-selection, and driving: Propensity score matching with multiple treatments. Transportation Research Part A, 44(10), 797-805.

Cervero, R (1996). Mixed land-uses and commuting: Evidence from the American Housing Survey. Transportation Research Part A, 30(5), 361-377.

Cervero, R, & Duncan, M. (2002). Residential self selection and rail commuting: A nested logit analysis. University of California Transportation Center Berkeley. California.

Chen, C, Gong, H, & Paaswell, R. (2008). Role of the built environment on mode choice decisions: Additional evidence on the impact of density. Transportation, 35(3), 285-299.

Crane, R. (2000). The influence of urban form on travel: An interpretive review. Journal of Planning Literature, 15(1), 3-23.

EPA. (2006). Greenhouse gas emissions from the U.S. transportation sector, 1990-2003. Washington, DC: Environmental Protection Agency.

Ewing, R, & Cervero, R. (2010). Travel and the built environment. Journal of the American Planning Association, 76(3), 265-294.

Frank, L.D, Bradley, M, Kavage, S, Chapman, J, & Lawton, T.K (2008). Urban form, travel time, and cost relationships with tour complexity and mode choice. Transportation, 35(1), 37-54.

Frank, L.D, & Engelke, P. (2005). Multiple impacts of the built environment on public health: Walkable places and the exposure to air pollution. International Regional Science Review, 28(2), 193-216.

Frank, L.D, Greenwald, M.J, Kavage, S, & Devlin, A. (2011). An assessment of urban form and pedestrian and transit improvements as an integrated GHG reduction strategy: WSDOT.

Frank, L.D, Saelens, B.E, Powell, K.E, & Chapman, J.E (2007). Stepping towards causation: Do built environments or neighborhood and travel preferences explain physical activity, driving, and obesity? Social Science & Medicine, 65, 1898-1914.

Frank, L.D, Sallis, J. F, Conway, T.L, Chapman, J.E, Saelens, B.E, & Bachman, W. (2006). Many pathways from land use to health: Associations between neighborhood walkability and active transportation, body mass index, and air quality. Journal of the American Planning Association, 72(1), 75-87.

Frank, L.D, Stone, B, & Bachman, W (2000). Linking land use with household vehicle emissions in the central puget sound: methodological framework and findings. Transportation Research Part D, 5(3), 173-196.

Friedman, M.S, Powell, K.E, Hutwagner, L, Graham, L.M, & Teaque, W.G. (2001). Impact of changes in transportation and commuting behaviors during the 1996 Summer Olympic Games in Atlanta on air quality and childhood asthma. The Journal of American Medical Association, 285(7), 897-905.

Handy, S. (2006). Self-selection in the relationship between the built environment and walking. Journal of the American Planning Association, 72, 55-74.

Handy, S.L. (2005). Smart growth and the transportation-land use connection: What does the research tell us? International Regional Science Review, 28(2), 146-167.

Handy, S.L, Cao, X, & Mokhtarian, P.L (2005). Correlation or causality between the built environment and travel behavior? Evidence from Northern California. Transportation Research Part D, 10, 427-444.

Hong, J , & Shen, Q. (2013). Residential density and transportation emissions: examining the connection by addressing spatial autocorrelation and self-selection. Transportation Research Part D, 22, 75-79.

Hong, J., & Goodchild, A. (2014). Land use policies and transport emissions: Modeling the impact of trip speed, vehicle characteristics and residential location. Transportation Research Part D, 26, 47-51.

Hong, J., Shen, Q, & Zhang, L. (2014). How do built-environment factors affect travel behavior? A spatial analysis at different geographic scales. Transportation, 41(3), 419-440.

Krizek, K.J. (2003a). Neighborhood services, trip purpose, and tour-based travel. Transportation, 30(4), 387-410.

Krizek, K.J. (2003b). Residential relocation and changes in urban travel: Does neighborhood-scale urban form matter. Journal of the American Planning Association, 69(3), 265-281.

Kwan, M, & Weber, J (2008). Scale and accessibility: Implications for the analysis of land use-travel interaction. Applied Geography, 28(2), 110-123.

Mokhtarian, P.L, & Cao, X (2008). Examining the impacts of residential self-selection on travel behavior: A focus on methodologies. Transportation Research Part B, 42 (3), 204-228.

Stone, B. (2007). Urban sprawl and air quality in large US cities. Journal of Environmental Management, 86(4), 688-698.

Zegras, C. (2010). The built environment and motor vehicle ownership and use: Evidence from Santiago de Chile. Urban Studies, 47(8), 1793-1817.

Zhang, L, Hong, J, Nasri, A, & Shen, Q. (2012). How built environment affects travel behavior: A comparative analysis of the connections between land use and vehicle miles traveled in US cities. Journal of Transport and Land Use, 5(3), 40-52.