Civil Engineering Reference
In-Depth Information
Table 17.4
Illustrative guidelines for suburban street access and spacing
Facility
Item
A
Freeway
B
Strategic
arterial
a
“
C
Arterial
D
Continuous
access
collector
E
Local
access
collector
F
Local
streets
Boulevard
”
Access
Access control
Full
Partial
Partial
Safety
Safety
Safety
Full
b, c
Direct property access
None
Right in/
out
b
Full
Full
Full
Interchange with
B, C
A, B, C
A, B, D
B, C, E
D, F
E
Continuity
Continuous Continuous
Continuous Continuous
1/2 MI
300
′
-
1,000
′
Spacing
Street spacing
6
d
1
e
1
e
4
-
6MI
1/4
1/8
-
1/16
100
′
Cross street spacing
1
-
2
½
1/2
1/4
1/8
-
1/16
Traf
c signal spacing
based on through band
width (%)
50
-
60
40
-
50
30
-
40
-
-
-
Source
Reference [
14
],
©
National Academy of Sciences, Washington, DC, 2000. Reproduced with permission
of the Transportation Research Board
a
“
Expressways
”
would have similar features except that there would be no direct property access. Direct
property access could be prohibited where reasonable alternative access is available
b
Direct property access may be prohibited where reasonable alternative access is available. Residential access
would be prohibited
c
Left turn exits from developments may be prohibited
d
Locate midway between freeway whenever freeway spacing exceeds 5 miles
e
Combined spacing of arterials and continuous collectors would be 0.5 miles
Illustrative suburban street access and spacing guidelines for suburban areas are
shown in Table
17.4
.
These guidelines would apply where population densities range from 2,500 to
7,500 people per square mile. For higher population densities, closer, continuous
street spacing should be provided.
17.2.4 New Roads and Roadway Widening
Adding capacity through road construction and widening has been the traditional
way to address traf
c congestion problems. New roadways, particularly Interstate
freeways, played a major role in expanding capacity to keep pace with population
and automobile growth and in decentralizing urbanization in the decade following
World War II.
