Density of freight/freight mix
To achieve a good freight mix on average, one method
employed by the industry is the use of a two-tiered transportation
network involving a
clique of large freight way-stations (called "breakbulks",
for example), with smaller freight "terminals"
fanning out from each breakbulk facility.
The philosophy behind the "breakbulk approach"
is that by consolidating a large amount of freight from
dispersed locations (i.e. from the connected terminals),
a larger and more diverse pool of freight is available to
choose from so as to achieve better freight mix for the
long haul between breakbulks. For example, the freight coming
from one terminal location may be relatively light and bulky,
whereas the freight fom another terminal location may tend
to be much denser. Some freight may be irregular in shape.
By consolidating the freight originating from multiple terminals
in one location, there is a wider range of freight to choose
from, so as to efficiently
pack each trailer for the long inter-breakbulk journey.
In this terminal-breakbulk network, a typical shipment
would first be picked-up from a customer location and dropped
off at the local terminal. It would then be trucked a relatively
short distance (a couple hundred miles, for example) to
the terminal's associated breakbulk. From there, the shipment
would be trucked a relatively long distance to the breakbulk
associated with the destination terminal, and then finally
trucked to the destination terminal, to be delivered to
the customer. The continual goal in this network is, however,
to minimize transfers of freight. Ideally, only one or even
no break bulks are involved in the process.