Geoscience Reference
In-Depth Information
willnottravel;yet,reasonableassumptionscanbemadeforthetripratefunctionbetween
an originand a destination and travel times.
In this paper the measure used for the network performance is the total delay of the
passengers of the network. This is defined as the increase in the total travel time caused
by earthquake induced damages. Essentially, it is the difference between the total travel
time of the damaged network and the total travel time of the undamaged network. The
total travel timeis computed by thefollowing equation:
T
=
x
i
t
i
(
x
i
)
(19.5)
all links
x
i
t
i
(
x
i
)
−
D
=
T
be f ore
−
T
after
=
x
i
t
i
(
x
i
)
(19.6)
all links
be f ore
all links
after
where
x
i
istheflow onlink
i
t
i
(
x
i
)
is thetravel timeon link
i
T
be f ore
isthetotal travel time before the event
T
after
isthetotal travel time after the event
D
is thetimedelay caused by the event
and the primes refer tothe parameters before theevent.
Thetraveltimeonalinkiscalculatedbyutilizingalinkperformancefunctiondeveloped
by the United States Bureau of Public Roads given as follows:
1
β
a
V
C
t
c
=
t
f
+
(19.7)
where
t
c
isthe congested link travel time
t
f
isthefreeflow linktraveltime
V
isthelink volume
C
isthelink capacity
,β
a
arecalibration parameters, specific to the study region
