11.188 Final Project: MBTA & The Urban Ring
by Jerrad Pierce <belg4mit@mit.edu>
Also available at http://web.mit.edu/belg4mit/www/11.520/final/
Introduction
I examined Urban Ring proposal with data accquired from the MassGIS and MBTA
websites. The MBTA data was a textual proposal and required the use of
geocoding, which was corroborated by MapQuest.com. To fully understand the
Urban ring it is necessary to perform a background study of the T. There is a
strong correlation between the T and the road
system.
Existing lines
There are centers of high population density
along the Green Line. The Green Line is the oldest line in the T; and the
first subway in the United States; and created for the purpose of exporting
population. Population density was calculated as population over inhabited
area. The inhabited area was calculated by using the Overlay Erase operation
in ArcToolbox to remove designated open space and water bodies from census
blocks to leave the real inhabited area.
Median household income correlates with MBTA service coverage and population
density. Higher income communities are located
farther from the hub and along the Green Line. Instead of using Jenks for the
breaks in this map, multiples of the Federal Poverty level (FPL, as described
at http://www.massbudget.org/povertydrop.pdf
were used. Due to the high cost of living (particularly housing costs) in
Greater Boston the 4 person value was used as the minimal FPL $17,960.
Average household size exhibits an
interesting spatial pattern. Household size, as calculated by the following
formula
(
1*[NF_HSHLD_1] +
2*[F_HSHLD_2] + 2*[NF_HSHLD_2]+
3*[F_HSHLD_3] + 3*[NF_HSHLD_3]+
4*[F_HSHLD_4] + 4*[NF_HSHLD_4]+
5*[F_HSHLD_5] + 5*[NF_HSHLD_5]+
6*[F_HSHLD_6] + 6*[NF_HSHLD_6]+
7*[F_HSHLD_7] + 7*[NF_HSHLD_7]
) / [TOT_HSHLD]
does not map well to neither density nor income. This discrepancy is largely
due to Chelsea, Dorchester and Milton.
Coverage
To determine the efficiency of service I compared the cumulative population
coverages of 1500 foot buffers (a 5 minute walk, which is the normal
approximation for maximum distance comfortable to a pedestrian) around all T
stations that were dissolved vs. undissolved buffers. This was done using
the Spatial Analyst's Zonal Statistics function. After determining that
the current layout double counted people due to the high station density on
the Green Line I crated an optimized system. The new system was created with
use of existing tracks and stations, removal of some Green Line stations
and filling gaps near population centers (primarily along the Red and Orange
Lines). The proposed system serves more people, promotes infill, and higher
throughput due to fewer stops (Green Line).
Urban Ring
The Urban is not a ring per se, due to numerous alternate sites and the
restrictions of existing infrastructure. The Urban Ring was conceived as
a means of promoting mobility by reducing the necessity of trips through
the urban center and is similar in principle to a highway bypass. A secondary
goal of the ring is to promote infill
(density),
indicated by the low degree of overlap with existing coverage and the variety
of densities served.
Coverage
The Urban Ring may, in practice, be an extension of Green or Orange, and
probably only partially rail. The Urban Ring
would serve a mix of land uses, similar
to the existing lines, with an emphasis on industry and transportation. The
latter is somewhat to b expected given the concept of the Urban Ring as a
bypass worked into the existing infrastructure.
Conclusion
Based on my analysis, I think the sites chosen for the Urban Ring are
excellent and the project should move forward as soon as possible. I would
also like to see the entire system become light or heavy rail, and not bus
based. Finally, as an aesthetics and end-user issue I would discourage the
MBTA from merging the Urban Ring with an existing line; particularly the
labyrinthine Green Line.