Information Technology Reference
In-Depth Information
The request will be transferred to the bidder with the lowest bid price if this
price is lower than the auctioneer's own marginal costs.
3 Problem Definition
Suppose a horizontal carrier coalition with
m
independent members. Each mem-
ber
i
,
i
=1
,...,m
, acquires FTL requests from customers during the entire time
horizon [0
,
i
=1
R
i
∞
]. The set of requests of carrier
i
is denoted as
R
i
.Let
R
=
∪
denote the set of all requests to be served. A request
r
R
must be transported
from its pickup location to the corresponding delivery location. At each location
u
, the operation (pickup or delivery) must be started in a customer defined time
window [
a
u
,b
u
]. The service time at
u
is given by
s
u
. In a static PDP, all request
information is available at the time of planning. In a dynamic PDP, however,
requests may be released while the routes are executed. The time when a request
r
is released to a carrier is called the release time
t
rl
r
.Anyrequest
r
in carrier
i
's request portfolio
R
i
can be executed by a vehicle
k
of
i
's own fleet
K
i
which
is called
self-fulfillment
or by
subcontracting
it to a common carrier outside the
coalition. In case of subcontracting, a certain price
γ
r
must be paid. At the be-
ginning of the whole time horizon (
t
0
= 0), the vehicles in
K
i
are staying at
different locations. Let
K
=
∈
i
=1
K
i
denote the entire fleet of the coalition. All
vehicles in
K
are homogeneous so that every request in
R
can be fulfilled by any
vehicle in
K
. However, all carriers may use their own scheme to calculate route
costs for their own fleet, i.e., the vehicles may have different variable cost
β
k
.
In case of
isolated planning
(IP), in which no request is exchanged among
the member carriers, the dynamic transportation planning problem consists of
constructing request fulfillment plans for each carrier
i
such that all requests in
portfolio
R
i
are fulfilled either by self-fulfillment or subcontracting. The total
costs of IP include the route costs for all vehicles owned by partners and the
charges paid to common carriers for subcontracting. In the
collaborative planning
scenario, carriers have a third request fulfillment option besides self-fulfillment
and subcontracting which is to exchange requests with other partners. Each
exchange results an internal payment among the participating members of the
coalition. The expenses of acquired requests through exchange will be covered
by such internal payments so that no member will get worse off. Associated with
the payments, the responsibility of the fulfillment of the transferred requests is
also shifted. A member who gets some requests from others must guarantee the
fulfillment of these requests. However, they can choose either to fulfill them using
their own vehicles or by subcontracting. In the latter case, they have to pay the
freight charges to the common carriers on their own.
∪
4 Solution Approach
To solve the DCTPP, the route-based request exchange mechanism proposed for
the static CTP in [31] is integrated into a rolling horizon planning framework.
