Civil Engineering Reference
In-Depth Information
driver imposes on all drivers in the highway. Using only the travel time cost
component of a trip, the relationship of average user cost and marginal social cost
(aggregated for all users) is illustrated in Fig.
19.2
.
The marginal social cost (MSC) can be calculated as:
MSC
@
V
n
þ
1
¼ AC
@
V
n
þ
V
n
AC
@
½
ð
V
n
þ
1
Þ
AC
@
ð
V
n
Þ
ð
19
:
1
Þ
where:
GTC Generalized trip cost = [(time cost) + (vehicle operating cost) + (road
maintenance cost)]
AC Average driver trip cost
MSC Marginal social cost = (the trip cost to the average driver) + (the cost
imposed on all drivers by an additional driver to the traf
c stream)
V
n
Vehicles per hour per lane
V
n+1
V
n
+ one additional vehicle
V
max
The maximum number of vehicles per hour per lane
Illustrative Example
The congestion price may be de
ned as an incremental charge (congestion
charge) paid by a motorist using a congested road to ensure that she or he pays a
Fig. 19.2 Average cost and marginal (social) cost curves
