Civil Engineering Reference
In-Depth Information
16.8.1 Benefits from Applications
This strategy has the potential to achieve signi
cant delay reductions where traf
c
fl
flows are highly unbalanced. Its implementation can bene
t from applications of
automated traf
c control technologies such as sensors and lane control signals.
Delays can be minimized when left turns are prohibited along arterial streets during
the hours that the reversible lanes operate.
Reversible lanes provide an effective means of accommodating tidal variations
in traf
flow on roadways connecting the city center or other major activity
center with residential areas. Capacity increases in the peak direction of
20
c
fl
with corresponding reductions in travel time.
Accident reductions up to 30 % have been reported; however, they probably
re
50 % have been reported
—
-
fl
ect the drop in congestion-related rear end crashes [
22
].
Application of this strategy along Memorial Drive in Atlanta, GA showed that
peak travel times in the major-
fl
ow direction decreased by 25 % in the am peak,
and 24 % in the pm peak [
23
]
Reversible lanes along 6 miles of 7th Ave. in Phoenix AZ, increased speeds about
25 % in the AM peak period and 16 % in the PM peak period, but there was a 28 %
increase in crashes. The annual cost of crashes and sign installation was $175,000,
while the annual travel time savings were valued at about $1,000,000 [
18
].
Table
16.7
illustrates how the per lane demand-to-capacity ratio of a four-lane,
2-way street can be better balanced through reversible lane operations of lane #3.
16.8.2 Types and Extent of Applications
Reversible lanes are generally applied along radial arterial streets and freeways.
They are also used at many bridges/tunnels and toll plazas. Sometimes entire streets
are made reversible.
Table 16.7 Illustrative example of the effect of reversible-lane operation on the per lane demand-
to-capacity ratio of a hypothetical 4-lane arterial street
Lane 1
Lane 2
Lane 3
Lane 4
Before
Direction
NB
NB
SB
SB
Demand volume (VPH)
600
600
200
200
Capacity (VPH)
650
650
650
650
Demand/capacity
0.92
0.92
0.31
0.31
After
Direction
NB
NB
NB
SB
Demand volume (VPH)
400
400
400
400
Capacity (VPH)
650
650
650
650
Demand/capacity
0.62
0.62
0.62
0.62
Source
Estimated
