Geoscience Reference
In-Depth Information
emissions in the CBD by 20-28 %. They create conditions for the distribution of
emissions throughout the metropolitan area. The question of distributing
emissions over a large area, such as a metropolitan area, is important in itself,
since researchers usually deal with the general issue of total emission reduction,
rather than in a concentrated or particular area like the CBD.
Note that the results presented in this paper suggest that a more aggressive
parking policy is needed to obtain a significant reduction in pollutant emissions.
For example, in the dataset used for this paper, the increase in parking fees only
reduces VHT if the increase is 75 % or more.
The parking policies analyzed in this paper are assumed to change the
demand for travel; the supply side (transportation network, alternative modes)
was assumed to be constant. The pollutant emissions were then calculated
according to link flows and travel times produced by solving the traffic assign-
ment problem. The paper shows that the emissions may also increase in certain
sections of the metropolitan area because of the redistribution of trips.
Such a solution is in accordance with the existing transit level of service in the
TAMA. Public transit level of service is most efficient in high-density areas,
such as the CBD and its nearby suburbs. The demand for travel in the outskirts of
the metropolitan area cannot be supported by transit because of their dispersed
spatial development. Therefore, such parking-policy measures as increased
parking fees and/or reduced parking supply in the CBD could influence both
travel destination and mode choice.
The pollutant-emission model shows that there is an advantage in imple-
menting parking policies in the CBD, even without supportive measures such as
improving public transport level of service or imposing toll roads. Decreasing
overall metropolitan pollution emissions and distributing emissions so as to
lower pollutants in the CBD have a positive effect on overall metropolitan air
quality.
The vicious cycle in which transportation planners use parking availability
for road-capacity planning should be replaced with parking-policy measures.
This step could offer a basis for combining additional policy measures and
examining the influence of additional transport policies, such as planning for
slow modes, imposing toll roads, and improving public transport level of service,
on the degree of air-pollutant emissions.
Acknowledgment
This research was partially supported by the Henry Ford II Transportation
Research Fund.
References
Ben-AkivaM, Lerman ST (1985) Discrete choice analysis: theory and application to travel demand.
MIT Press, Cambridge, MA
Bernick M, Cervero R (1997) Transit villages in the 21st century. McGraw-Hill Co, New York
Burton E (2000) Measuring urban compactness in UK towns and cities. Environ Plan B Plan Des
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