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Commuting Sustainably: Do Smart Growth Policies Affect Transportation?

Authors:

Abstract

One of the goals of urban planning ’smart growth’ policies is providing a variety of transportation options and promoting the use of carpooling, public transportation, bicycling, and walking, all of which are considered more sustainable than driving alone. This paper examines the relationship between sustainable transportation and the presence of state­-level smart growth policies using a difference­-in-­differences analysis with data from the U.S. Census Bureau’s American Community Survey. Given that Maryland enacted state-­level smart growth policies in 2009 and 2010, this paper compares the Baltimore metropolitan area to the Denver metropolitan area, which has no state-­level smart growth policies but some demographic similarities to the Baltimore metropolitan area. This analysis finds a 2.2 percentage point increase in sustainable transportation use in Baltimore attributable to the smart growth policies in Maryland that were passed in 2009 and 2010.
Riordan Frost, PhD Candidate
Department of Public Administration & Policy, American University
Commuting Sustainably
The role of state smart growth policies in transportation
References
2013. “2008-2012 American Community Survey 5-Year Estimates — Tables S1903, S1501, B01003.” US Census Bureau. http://www.census.gov/acs/www/index.html.
2013. "About Smart Growth." US Environmental Protection Agency. http://www.epa.gov/smartgrowth/about_sg.htm.
2013. “Fast Facts: U.S. Transportation Sector Greenhouse Gas Emissions 1990-2011.” US Environmental Protection Agency. http://www.epa.gov/otaq/climate/documents/420f13033a.pdf
2014. "2013 American Community Survey — Table S0801." US Census Bureau. http://www.census.gov/acs/www/index.html.
2014. "Smart Growth Planning Topics." Maryland Department of Planning. http://www.mdp.state.md.us/OurWork/smartgrowth.shtml.
2015. "What is "smart growth?" Smart Growth America. http://www.smartgrowthamerica.org/what-is-smart-growth.
Anthony, Jerry. 2004. "Do State Growth Management Regulations Reduce Sprawl?" Urban Affairs Review 39 (3): 376-397.
DeLoach, Stephen B, and Thomas K Tiemann. 2012. "Not driving alone? American commuting in the twenty-first century." Transportation 39 (3): 521-537. doi: 10.1007/s11116-011-9374-5.
Ferguson, Erik. 1997. "The rise and fall of the American carpool: 1970–1990." Transportation 24 (4): 349-376. doi: 10.1023/A:1004928012320.
Glaeser, Edward L., Matthew E. Kahn, and Jordan Rappaport. 2008. "Why do the poor live in cities? The role of public transportation." Journal of Urban Economics 63 (1): 1-24. doi: 10.1016/j.jue.2006.12.004.
Ingram, Gregory, Armando Carbonell, Yu-Hung Hong, and Anthony Flint, eds. 2009. Smart Growth Policies: an evaluation of programs and outcomes. Cambridge, MA: Lincoln Institute of Land Policy.
Jun, Myung-Jin. 2008. "Are Portland's Smart Growth Policies Related to Reduced Automobile Dependence?" Journal of Planning Education and Research 28 (1): 100-107. doi: 10.1177/0739456x08319240.
Kahn, Matthew E., and Eric A. Morris. 2009. "Walking the Walk: The Association Between Community Environmentalism and Green Travel Behavior." Journal of the American Planning Association 75 (4): 389-405.
Literature Review
What affects how we get around?
The cost of each mode: driving alone decreases when fuel costs rise, and sustainable modes all decrease
when fuel costs fall (Ferguson 1997; DeLoach & Tiemann 2012)
Income: low-income commuters carpool and take public transportation more, due to the lower user cost
(Ferguson 1997; Glaeser et al. 2008)
Environmentalism: environmental views and sustainable mode choices are positively correlated on the
community-level (Kahn & Morris 2009)
What is the role of state smart growth policies?
State policies succeed in the areas states prioritize (Ingram et al. 2009)
Maryland prioritizes environmental protection, Oregon prioritizes transportation, New Jersey
prioritizes affordable housing
The Oregon planning law establishing the Portland urban growth boundary was not found to affect rates
of driving alone (Jun 2008)
States with growth management policies appear to experience lower density declines (Anthony 2004)
Research Question
Do state smart growth policies positively affect sustainable transportation rates?
Sustainable transportation: public transit, carpooling, bicycling, and walking
Empirical Approach
Using difference-in-differences analysis to compare sustainable transportation rates in Colorado and
Maryland before and several years after the 2009 and 2010 Maryland smart growth policies
This method compensates for non-random treatment and attempts to determine causal effects
To ensure there is no bias from pre-existing trends, event study analysis is conducted (see Fig. 4)
Two approaches: differencing and logistic regression
(Sustainable transportation)it = ƛ(β0 + β1(sg)ij + β2(year)jt + β3(yearjt*sgij) + β4(education)ijt + β5(ln(income)ijt)
+ β6(gender)ijt + β7(race)ijt + β8(rent/own)ijt)
Motivation
Driving alone is the most widely used, but least efficient mode of personal transportation
Driving contributes to congestion, local air pollution, and infrastructure burden — and
greenhouse gas emissions (see Fig. 1 & 2)
Alternative’ modes are encouraged by government and business programs for their societal
benefits and company benefits (e.g. less parking demand)
Here, these modes — public transit, walking, bicycling, and carpooling — are combined
into a new variable: ‘sustainable transportation
There are only 11 states with comprehensive smart growth policies
What is smart growth?
“Building urban, suburban and rural communities with
housing and transportation choices near jobs, shops and
schools” (Smart Growth America 2015)
A bundle of principles including mixing land uses, creating a
range of housing opportunities, providing a variety of
transportation choices, and preserving open space (EPA 2014)
Conclusions
Finding: there is approximately a 2 percentage point difference between the sustainable transportation rates in
Baltimore and Denver, attributable to the state smart growth policies of Maryland
A two percentage point difference is a 10% increase in current sustainable transportation rates
This change results in substantial GHG mitigation (see Fig. 1 & 2)
Limitations: more than one policy passed in Maryland; no uniform policy across states for comparison; !
no non-commuting data available
Next steps: look at other metropolitan areas; examine other smart growth goals (e.g. mixed uses, affordable
housing, and open space); use synthetic controls instead of difference-in-differences
Sustainable Transportation
15%
16%
17%
18%
19%
20%
21%
2005
2006
2007
2008
2009
2010
2011
2012
2013
Baltimore MSA Denver MSA
Figure 2: Cars and light-duty trucks’ share of
transportation GHGs in 2011 (Source: EPA 2013)
Medium and
Heavy-Duty Trucks
22%
Passenger Cars &
Light-Duty Trucks
61%
Ships & Boats
3%
Other
6%
Aircraft
8%
Figure 1: Transportations share of US GHGs
in 2011 (Source: EPA 2013)
Agriculture
9%
Industry
28%
Residential
17%
Transportation
27%
Commercial
17%
Figure 3: 2013 commuting by mode in the US (excluding work-at-home and misc.)
(Source: US Census Bureau 2014; own work)
Drive alone
Carpool
Public transit
Walk
Bicycle
76%
9%
5%
3%
(0.6%)
How do we get to work?
Table 2: Difference-in-differences
Sustainable
Transportation %
Pre (2008)
Post (2013)
Difference
Denver (control)
20.06%
17.09%
2.97%
Baltimore (treatment)
18.99%
18.49%
0.5%
Difference
1.07%
-1.4%
2.47%
Data
American Community Survey data from the Integrated Public Use Microdata Series (IPUMS-USA)
Denver and Baltimore metropolitan areas chosen due to similar demographics and the fact that
Maryland has state smart growth policies and Colorado does not
Metropolitan areas chosen to include the transportation behaviors of urban and suburban residents
Pooled cross-sectional sample: N = 47,000
Baltimore-Towson, MD
Denver-Aurora-Broomfield, CO
Population (2012)
2,715,650
2,554,243
Median HH Income (2012)
$68,616
$62,407
% College Educated (2012)
35.4%
38.7%
Table 1: Similarities between Baltimore and Denver MSAs (Source: Census Bureau 2013)
Table 3: Logistic regression DD - average partial effects
*** p<0.01, ** p<0.05, * p<0.1
Smart growth
(Baltimore)
-0.010
(0.006)*
Year
-0.040
(0.006)***
Year * smart growth
0.018
(0.009)**
Education (ref: college)
-0.015!
(0.005)***
Ln(income)
-0.043!
(0.002)***
Gender (ref: female)
-0.020!
(0.004)***
Race (ref: white)
-0.074!
(0.005)***
Rent/own (ref: renter)
0.093!
(0.005)***
Observations
47,410
Results
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Smart Growth Policies: an evaluation of programs and outcomes
  • Gregory Ingram
  • Armando Carbonell
Ingram, Gregory, Armando Carbonell, Yu-Hung Hong, and Anthony Flint, eds. 2009. Smart Growth Policies: an evaluation of programs and outcomes. Cambridge, MA: Lincoln Institute of Land Policy.
Fast Facts: U.S. Transportation Sector Greenhouse Gas Emissions
2013. "2008-2012 American Community Survey 5-Year Estimates -Tables S1903, S1501, B01003." US Census Bureau. http://www.census.gov/acs/www/index.html. 2013. "About Smart Growth." US Environmental Protection Agency. http://www.epa.gov/smartgrowth/about_sg.htm. 2013. "Fast Facts: U.S. Transportation Sector Greenhouse Gas Emissions 1990-2011." US Environmental Protection Agency. http://www.epa.gov/otaq/climate/documents/420f13033a.pdf 2014. "2013 American Community Survey -Table S0801." US Census Bureau. http://www.census.gov/acs/www/index.html. 2014. "Smart Growth Planning Topics." Maryland Department of Planning. http://www.mdp.state.md.us/OurWork/smartgrowth.shtml. 2015. "What is "smart growth?" Smart Growth America. http://www.smartgrowthamerica.org/what-is-smart-growth.