Environmental Engineering Reference
In-Depth Information
tool for emission reduction is to reduce idling and queuing times. Lazic ( 2004 ) reveals
that approximately 70 % of the emission at a container terminal comes from trucks.
They also reports that this is because of their waiting time to be processed and run-
ning engines for air conditioning and heating. Therefore, reducing idling and queu-
ing time of trucks can significantly reduce the emissions at container terminals. This
has received significant attention, as these truck emissions probably have more harm-
ful impact—relative to the emitted amounts—when emitted near local communities
(Saxe and Larsen 2004 ). There have been a number of studies and industry reports on
truck emission reduction efforts at seaports. Some of these studies focus on the impact
of engine technologies on emission factors, e.g. Truck Stop Electrification (Zietsman
et al. 2009 ); while other studies focus on different mechanisms to coordinate termi-
nal and truck operations, for example Terminal Appointment System (TAS), tariff/toll
pricing policies and Vessel-Dependent Time Windows (VDTWs) for truck entries and
operational and capacity improvements (Karafa 2012 ).
Usually the yard of a container terminal can be divided into two areas: an
area for stacking export containers which will be loaded to vessels heading for
another container terminal, and an area for stacking import containers which
will be loaded to trucks and delivered to the consignees. To transport containers
inland, trucks are usually used for transporting containers into or out of the con-
tainer terminal. Shipping companies or 3rd party logistic companies (from now
referred to as shipping company for short) are in charge of this inland transporta-
tion. In order to cooperate with the container terminal manager, they register the
time for delivery or picking up the import containers via TAS that is a web-based
system. Usually, there is no change after the shipping company makes the registra-
tion. Based on the registrations, the manager of container terminal will arrange the
container handling equipment to load/unload container when trucks arrive. Import
containers are unloaded from vessels and stacked at the import yard. The officer
of container terminal will inform the shipping company about picking up contain-
ers. Export containers are unloaded from trucks and stacked at the export yard.
Stacking export container is more complicated than stacking import container. The
reason is that vessels are berthed as short time as possible at the container ter-
minal due to high berthing cost. Export containers should be stacked in the right
order so that they fit with the stowage plan and can be loaded onto the vessel in
a short period time. There have been many studies on how to optimize the export
container stacking. The decision on export container stacking is made before ves-
sels arrive. However, the arrival rate of trucks in a given period of time in a day
varies. E.g. collected data studied from port of Los Angeles (POLA) (Chen et al.,
accepted) and other container terminals shows that the arrival rate is high from 8
to 9 a.m. and from 6 to 7 p.m. while shipping company can register any period
from 0 a.m. to 23 p.m. for picking up containers. This means that the shipping
companies prefer to deliver or pick up containers at the beginning or at the end
of a working day. Waiting time of trucks may be lengthened due to the number
of handling operations of yard cranes. For example, if a truck arrives to pick up a
container at the bottom of a stack, the yard crane has to move all the upper con-
tainers so that it can reach the required container, which means longer waiting
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