Attachment A
DATE:
October 12, 2007
TO:
Interested Parties
FROM:
Ben Dowling
RE:
Greenline Extension: Medford-Somerville versus Arlington-Belmont
Summary
Because of trip flows, propensities to take transit, and population density, the
currently proposed Greenline extension corridor, through Medford-Somerville,
holds greater potential transit demand than does a corridor through ArlingtonBelmont.
Greenline or Redline Extension?
Comparing the Arlington-Belmont corridor against the currently proposed
Greenline extension corridor (through Medford-Somerville) only makes sense if it
is assumed that the Redline, not the Greenline, would be extended to serve
Arlington-Belmont. This assumption is dictated by logic and geography.
Arlington and Belmont are the next communities past Alewife (the Redline’s
current terminus). Also, any new Greenline service to Arlington-Belmont would,
by definition, be somewhat duplicative because of geography and the Redline’s
current alignment, which would parallel or even intersect, a Greenline extension
to Arlington-Belmont.
Population Density
Population densities around the currently proposed Greenline alignment (through
Medford and Somerville) suggest this corridor would be more supportive of fixed
guideway transit service than would a corridor in Arlington-Belmont which
would require construction of extensive park and ride facilities to match the
transit potential of the Medford-Somerville corridor, without parking. In the year
2000, Belmont had a relatively low population density of 5,211 people per square
mile. Arlington had a relatively high population density of 8,255 people per
square mile but that was still far below the 13,329 people per square mile density
of the areas in Somerville and Medford adjacent to the currently proposed
Greenline alignment.
Figure 1: Population per square mile for Arlington-Belmont and Medford-Somerville
Square
2000
Pop./sq.
Miles Population
mi.
2.42
57,769 23,868.41
Boston Proper1
Medford Somerville
Corridor
Somerville
Medford
Arlington
Belmont
4.10
4.11
8.12
5.13
4.64
54,692
77,493
55,766
42,389
24,194
13,329.35
18,836.13
6,870.11
8,255.92
5,211.77
Year 2000 Census Journey To Work Data
Census data also suggests that the currently proposed Greenline alignment through
Medford-Somerville is better than an alternate alignment through Arlington-Belmont.
Census Journey To Work data shows that in the year 2000 some 11,750 people traveled
from Medford and Somerville to Boston Proper for work. In the same year Arlington and
Belmont sent less than half that volume to Boston Proper (5,010). Similarly, the transit
share from Arlington and Belmont to Boston (56%) was lower than the transit share from
Medford and Somerville (65%).
Figure 2: 2000 Census Journey To Work Data for Arlington-Belmont and MedfordSomerville
TOWN
RESIDENCE
Medford
Somerville
Arlington
Belmont
1
TOWN
WORK
Boston
Boston
Boston
Boston
Total
4,380
7,370
3,109
1,901
Drive
Alone
1,474
1,545
885
838
Carpool
352
361
121
267
Bus
832
768
405
136
Other
Transit
1,697
4,345
1,647
634
Other
Mode
25
351
51
26
Boston Proper is defined as the peninsula bounded by the Charles River, Boston Harbor, Fort Point
Channel, E. Berkley St., Warren Ave., Columbus Ave and then Massachusetts Ave. back to the Charles
River.
Transit
Mode
Share
57.74%
69.38%
66.00%
40.50%