Civil Engineering Reference
In-Depth Information
Fig. 23.1 Probability of commuting by transit as a function of auto ownership, for four land use
scenarios.
Note
Based on modeling of survey results from the 11 metropolitan areas (MSAs or
CMSAs) of Boston
-
Lawrence
-
Lowell, Dallas, Detroit, Los Angeles
-
Long Beach, Fort Worth
-
Arlington, Minneapolis
-
St. Paul, Philadelphia, Phoenix, San Francisco
-
Oakland, Tampa
-
St.
Petersburg, and Washington, DC-MD-VA.
Source
Reference [
5
], pp 15
-
57. Figure 15.5 [
2
]
Employment and residential concentrations determine the potential transit
demand. These relationships are conceptually shown in Table
23.3
for ranges of
density.
The best transit markets are created where
both
employment and residential
densities are high
a condition that exists in major world cities. However, CBD
employment density is generally more important than the residential density of
within a catchment area of 45 min travel time to the CBD.
—
Conversely, the weakest transit markets exist where both employment densities
and residential densities are low. This condition exists in many smaller and
medium sized US metropolitan areas.
Table 23.3 Generalized transit potential of CBD employment density and population density
within 45 min of the CBD
Population density within 45 min of the CBD
CBD employment density
High
(>50,000/mi
2
)
Medium
(10,000
-
50,000/mi
2
)
Low
(<3,000
-
6,000/mi
2
)
High (>150,000/mi
2
)
+++++
++++
++
Medium (75,000
-
150,000/mi
2
)
+++
++
+
Low (<75,000/mi
2
)
+
-
-
Source
Estimated
