Environmental Engineering Reference
In-Depth Information
transport the goods are known as carriers, and in general, these could be for-hire
carriers, those that provide services to the open market; and private carriers, i.e.,
those that only provide transportation services to a parent or related company. To
transport freight, the shippers may contact the carrier companies directly or they
can use the services of intermediary companies, namely the third party logistics
(3PL) providers. Alternatively, shippers may use freight forwarders, i.e., a form of
3PL providers that make use of asset based carriers for shipping. The freight to be
transported may have as its destination a distribution center/warehouse, retailers,
wholesale traders, the end consumer or intermediate consumers. These agents and
facilities act as receivers of the cargo. Distribution centers are a special case of
facilities since they receive and distribute the cargo; at these locations the cargo
may be stored, consolidated, split up, post-processed or assembled. These pro-
cesses can have an impact on shipment size which in turn may affect the trans-
portation mode to be used when shipping. Other agents worthy of mention are:
wholesale retailers which in some occasions may act as distributors (shippers) of
the cargo, intermediate consumers which may process or transform the cargo
received and then ship it to the next destination and finally, the end consumers.Itis
important to note that delivering the cargoes to the end consumers, may require
additional logistical services as part of the cargo received, when consumed, turn
into waste that require further processing. In addition to the agents and facilities
just described, one can find intermodal centers (e.g., airports, ports, intermodal
terminals) that are facilities where the transfers between freight modes take place.
An important aspect of these facilities and distribution centers is the basis on
which they operate, i.e., in house or third party run, dedicated or general/shared
user facility, which can also affect the operation and decision-making process.
As a consequence of the multiple agents and facilities involved, no single agent
or facility operator can provide a complete picture of the freight system. This leads
to a situation in which assembling a coherent description of the whole requires
putting together the pieces provided by the different agents that are only aware of
the aspects that concern their operation. A summary of the information they are
aware of is shown in Table
1
.
As shown, producers and shippers of cargo typically have knowledge of the
characteristics of the cargo they receive/ship out. However, they do not know
much about what happens once the freight vehicles leave their facilities. Carriers
know the details of their operations—including the loaded and empty trips pro-
duced—though, quite frequently, they are not aware of the attributes of the cargo
transported. They know who they deliver to, though they do not necessarily know
who else is delivering to a particular customer. The consumers of the cargo, i.e.,
the receivers, know the details of the cargo they receive/ship out, though they do
not always know how many vehicle-trips have been generated because many of
them only observe the number of deliveries (a truck-trip could make multiple
deliveries). Transportation agencies have an idea about truck traffic in the network
and land use patterns. However, in most cases, they know very little about the
freight flows in their jurisdictions. In summary, none of the agents and facility
operators involved in freight has sufficient information to fully describe what
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