Documents provided during Public Comment regarding Item 5A: Approval of the Draft South Placer County District Transportation Expenditure Plan by Michael Garabedian
National Center
for Sustainable
Transportation
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0 Susan Handy
Department of Environmental Science and Policy
University of California, Davis
Issue
Reducing traffic congestion is often
proposed as a solution for improving fuel
efficiency and reducing greenhouse gas
(GHG} emissions. Traffic congestion has
traditionally been addressed by adding
additional roadway capacity via constructing
entirely new roadways, adding additional
lanes to existing roadways, or upgrading
existing highways to controlled-access
freeways. Numerous studies have examined
the effectiveness of this approach and
consistently show that adding capacity to
roadways fails to alleviate congestion for
long because it actually increases vehicle
miles traveled (VMT).
An increase in VMT attributable to increases
in roadway capacity where congestion
is present is called "induced travel". The
basic economic principles of supply and
demand explain this phenomenon: adding
capacity decreases travel time, in effect
lowering the "price" of driving; and when
prices go down, the quantity of driving
goes up. 1 Induced travel counteracts the
effectiveness of capacity expansion as a
strategy for alleviating traffic congestion and
offsets in part or in whole reductions in GHG
emissions that would result from reduced
congestion.
Key Research Findings
The quality of the evidence linking highway
capacity expansion to increased VMT
is high. All studies reviewed used time
series data and sophisticated econometric
techniques to estimate the effect of
increased capacity on congestion and
VMT. All studies also controlled for other
factors that might also affect VMT, including
population growth, increases in income,
other demographic factors, and changes in
transit service. 2
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Increased roadway capacity induces
additional VMT in the short-run and even
more VMT in the long-run. A capacity
expansion of 10% is likely to increase VMT
by 3% to 6% in the short-run and 6% to
10% in the long-run. Increased capacity
can lead to increased VMT in the short-run
in several ways: if people shift from other
modes to driving, if drivers make longer
trips (by choosing longer routes and/or
more distant destinations}, or if drivers
make more frequent trips. 3.4.s Longer-term
effects may also occur if households and
businesses move to more distant locations
or if development patterns become more
dispersed in response to the capacity
increase. One study concludes that the
full impact of capacity expansion on VMT
materializes within five years6 and another
concludes that the full effect takes as long as
10 years.7
Capacity expansion leads to a net increase
in VMT, not simply a shifting of VMT from
one road to another. Some argue that
increased capacity does not generate new
VMT but rather that drivers simply shift from
slower and more congested roads to the new
or newly expanded roadway. Evidence does
not support this argument. One study found
"no conclusive evidence that increases in
state highway lane-miles have affected traffic
on other roads"8 while a more recent study
concluded that "increasing lane kilometers
for one type of road diverts little traffic from
other types of roads".9
Increases in GHG emissions attributable
to capacity expansion are substantial. One
study predicted that the growth in VMT
attributable to increased lane miles would
produce an additional 43 million metric tons
of CO2 emissions in 2012 nationwide. 10
National Center for Sustainable Transportation • 1
UC Davis
Policy Briefs
Title
Increasing Highway Capacity Unlikely to Relieve Traffic Congestion Permalink
https://escholarship.org/uc/item/58x8436d
Author
Handy.Susan
Publication Date
2015-10-01
Powered by the California Di ital Librar
University of California
Capacity expansion does not increase employment
or other economic activity. Economic development
and job creation are often cited as compelling reasons
for expanding the capacity of roadways. However,
most studies of the impact of capacity expansion on
development in a metropolitan region find no net
increase in employment or other economic activity,
though investments do influence where within a
region development occurs.11· 12
Conversely, reductions in roadway capacity tend
to produce social and economic benefits without
worsening traffic congestion. The removal of
elevated freeway segments in San Francisco coupled
with improvements to the at-grade Embarcadero
and Octavia Boulevards has sparked an on-going
revitalization of the surrounding areas while
producing a significant drop in traffic.13 Many cities in Europe have adopted the strategy of closing streets
in the central business district to vehicle traffic as
an approach to economic revitalization, 14 and this
strategy is increasingly being adopted in cities the
U.S., from New York City to San Francisco.
Further Reading
This policy brief is drawn from the "Impact of
Highway Capacity and Induced Travel on Passenger
Vehicle Use and Greenhouse Gas Emissions" policy
brief and technical background memo prepared for
the California Air Resources Board (CARB) by Susan
Handy (University of California, Davis) and Marlon
Boarnet (University of Southern California), which
can be found on CARB's website along with briefs
and memos on 22 other land use and transportation
strategies that impact vehicle use and GHG emissions.
Website link: http://arb.ca.gov/cc/sb375/policies/
policies.htm
1 Noland, R.B. and LL. Lem. (2002). A review of the evidence for induced travel and changes in transportation and environmental policy in the US and the UK. Transportation Research D, 7, 1-26. http://bit.ly/ljZbllE 2 Noland, R.B. and LL. Lem. (2002).
3 Noland, R.B. and L.L. Lem. (2002),
• Gorham, R. (2009). Demystifying Induced Travel Demand. Sustainable Urban Transport Document #1. Transport Policy Advisory Services on behalf of the Federal Ministry of Economic Cooperation and Development, Bonn, Germany. http://bit.ly/lMszHfg 5 Litman, T. (2010). Generated Traffic and Induced Travel: Implications for Transport Planning. Victoria Transport Policy Institute. http://bit.ly/1 WXC258
6 Hansen, M. and Y. Huang. (1997). Road Supply and Traffic in California Urban Areas. Transportation Research A, 31(3), 205-218. http://bit.ly/lZvLOOk
7 Duranton, G. and M.A. Turner. (2011). The Fundamental Law of Road Congestion: Evidence from US Cities. American Economic Review, 101, 2616-2652. http://bit.ly/lMszTeD
8 Hansen and Huang. (1997).
9 Duranton and Turner. (2011).
10 Handy, S. (2005). Smart Growth and the Transportation-Land Use Connection: What Does the Research Tell us? International Regional Science Review, 28(2): 1-22. http://bit.ly/lNCeeSP u Handy, S. (2005).
12 Funderberg, R., H. Nixon, M. Boarnet, and G. Ferguson. (2010). New Highways and Land Use Change: Results From a Quasi Experimental Research Design. Transportation Research A, 44(2): 76-98. http://bit.ly/lLqY hfD 13 Cervera, R., J. Kang, and K. Shively. (2009). From Elevated Freeways to Surface Boulevards: Neighborhood and Housing Price Impacts in San Francisco. Journal of Urbanism, 2(1), 31-50. http://bit.ly/1LF8eSq 14 Hajdu, J.C. (1988). Pedestrian Malls in West Germany: Perceptions of their Role and Stages in their Development. Journal of the American Planning Association, 54(3). 325-335. http://bit.ly/lLqYnUy The National Center for Sustainable Transportation is a consortium of leading universities committed to advancing an environmentally sustainable transportation system through cutting-edge research, direct policy engagement, and education of our future leaders.
Consortium members: University of California, Davis; University of California, Riverside; University of Southern California; California State University, long Beach; Georgia Institute of Technology; and The University of Vermont
Visit us at ncst.ucdavis.edu Follow us on: Im �
2 • National Center for Sustainable Transportation
IF'l'ING GEARS
vnrcl o Now Woy of Thlnki119 ab01..1t Ir ,melpu1 t,,tior 1 1an Hondy
:ruciating traffic jams. Struggling transit agonclon. An opldemlc of podos n fatalities. It is clear that transportation is not working in tho United tes and that we need to rethink our approach. In Shifting Gears, Suaen 1dy provides an in-depth history of the ideas embedded in American ,sportation policy and the emergence of hew ways of thinking that could e us better transportation options. Weaving in bits of her own personal rative, Handy gives, readers a deeper and clearer understanding of our ,sportation system and the roots of its successes and failures.
Handy covers the myriad costs of car ownership, the futility of expand• highways, and the misplaced faith in technological innovation. She of� ; new ideas and strategies that can improve the health of our car-centric ,sportation system-most crucially, the idea that communities across the mtry must create an array of choices for daily travel. Shifting Gears asserts t a diverse transportation ecosystem is essential for creating more just, tainable communities, but .getting there will take a dramatic shift in how think about transportation. ''
.an Handy is Distinguished Profe�sor of Environmental Science and Policy :l Director of the National Center for Sustainable Transportation at the iversity of California, Davis, where she also. chairs the graduate pragram rransportation Technology and Polioy,
,an and Industrial Environments series
'ith accessible writing, academic:: rigor, and the right sense of the absurd, ;an Handy explains how American transport planning got us into this ss, and the path to get us out." .
leffrey Tumlin, Director, San Francisco Municipal Transportation Agency andy's illuminating history provides context for many rules and practices ., nd in transportation, highlighting where they do not serve today's needs :l making it clear why and how they need to change."
leth Osborne, Director, Transportation for America
ost cities want to make driving easier. In Shifting Gears, Susan Handy 1ws how cities can make it easier to drive less. Transportation officials and dents alike need to read this wonderful book, and they'll love it." )onald Sho�p, Distinguished Research Professor, Department of Urban nning, UCLA
er photos: (left) Eric Sehr, Flickr;
1t) Santa Rosa Press Democrat
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