Civil Engineering Reference
In-Depth Information
price that matches the MSC imposed by the driver on the rest of the drivers. This
de
nition is illustrated Fig.
19.3
, using only travel time as the generalized trip cost.
In this example a congestion charge (CC) of $0.80/mile is calculated as shown
below.
Assumptions
ATTR demand
ð
Þ
¼
average travel time rate
¼
ð
12
V
=
250
Þ
min
=
mile
ð
19
:
2
Þ
h
i
min
6
AART supply
ð
Þ
¼
average travel time rate
¼
1
þðV=CÞ
=
mile
ð
19
:
3
Þ
h
i
min
6
MTTR
¼
marginal travel time rate
¼
1
þ
7
ð
V
=
C
Þ
=
mile
ð
19
:
4
Þ
Value of travel time
¼
$
15
:
00
=
h
ð
19
:
5
Þ
Findings
Setting Eq.
19.2
equal to Eq.
19.3
,
finds that at a volume (V) of 2,500 vehicle/
lane/h, the TTR = 3.00 min/mile; and setting Eq.
19.2
equal to Eq.
19.4
,
nds that at
a volume (V) of 1,800 veh/lane/h, the TTR = 4.71 min/mile. But when the TTR =
4.71, the equilibrium volume (V) corresponds to 1,800 veh/h/lane. And when (V) =
1,800 veh/h/lane it is possible to travel at a rate of 1.53 min/mile.
Therefore the optimum congestion toll (b
c) is achieved at the price equivalent
-
of $0.80/mile or [(4.71
1.53) min/mile] * [($15.00/h)*(1 h/60 min)].
In this example the congestion charge of $0.80/mile will reduce the traf
-
c
volume from 2,250 to 1,800 veh/h/lane, and the TTR of an average driver from
3.0 min/mile to 1.53 min/mile.
Fig. 19.3 Determining the congestion price for a facility
