Civil Engineering Reference
In-Depth Information
Where it exists, this condition can (and should) be corrected by increasing
storage space on the connecting driveway, and by separating the left turns into and
out of the development. Figure
16.7
(bottom) shows that by increasing the storage
space and by separating con
icts are greatly reduced
and congestion can be reduced or eliminated. Additional examples of best access
practices are given in [
5
].
fl
icting left-turn access, con
fl
16.10.4 Traffic Speed and Safety Impacts of Access
Management Practices
The effects of access and traf
c signal frequency on traf
c speeds have been well
documented.
The 1994 Highway Capacity Manual [
28
] reported a speed reduction of
0.24 mph for every access point along unsignalized highways, and up to a
10 mph speed reduction for sections with 40 or more access points
Each traf
c signal per mile added along an arterial roadway reduces traf
c speed
by about 2
3 mph
-
The application of access management techniques has resulted in signi
cant
safety and level of service improvements, as shown in Table
16.8
[
29
].
Table
16.9
summarizes access management bene
c speeds and safety
from eight case studies. Speeds and safety improved at each location.
ts in traf
16.10.5 Conclusions
It is clear that access management is a desirable strategy from a congestion-
reduction perspective. A growing number of state and local transportation agencies
have implemented access management activities. However, others have not. This is
because
“
controlling or managing access along arterials is a dif
cult task facing
local of
culty comes from a time-
honored tradition, and in some cases a legal right, for land owners abutting a road to
have access to their land
cials and transportation engineers. This dif
[
7
].
However, there is a growing recognition of the importance of access manage-
ment in congestion mitigation, and of the need to better integrate access manage-
ment with corridor traf
”
c management and land development. Development density
and design, which greatly in
uence levels of transit service and pedestrian access,
will likely receive more emphasis in the future, as the
fl
“
”
green
goal of VMT
reduction is increasingly gaining popularity.
