The article discusses visually modeling a marine port system. It presents a simple model of a port as a "gate valve" regulating cargo flow from land to water transportation. However, a real port has many complex interrelated factors affecting throughput. It identifies three major port subsystems - quay, yard, and gate/railhead - that determine overall capacity. The subsystems and various external players like ocean carriers interact in complex ways. An integrated dynamic model can help ports address challenges and support strategic decisions.

1. 32 BC Shipping News April 2012
ports & terminals
R
ecently I attended the ECA ses-
sion hosted by the Chamber of
Shipping of British Columbia.
During the session, one could recognize
that among the many questions, there
was one that was outstanding: what
will happen to the local marine indus-
try after enforcement of the Emission
Control Area?
Further to this, I have also followed
some of Port Metro Vancouver’s pres-
entations during the past year, once
again the big question sounds like:
“should the economy change, one way
or another, what will be the outcome
for the local ports?”
The source of these kinds of ques-
tions is in fact the human mind’s
tendency for constructing a business
model and connecting all known exter-
nal and internal sensors, components
and stimulants to see the effect on the
output, and based upon that output,
make a decision for future moves.
Visualizing the dynamic models of a
marine port had been part of my past
job and designation as an instructor
and member of a maritime training in-
stitute, port and logistics faculty group.
I shall emphasize that all of these
dynamic models already exist in
the minds of CEOs and operational
mangers, but transferring the idea in
an understandable and interesting way
is another matter which I shall try to
accomplish in this short article.
The modelling approach in decision-
making and design aspects of marine
ports has gained greater attention as
managers face a problem area that is
very dynamic in nature. Researchers
have proposed different software pack-
ages and approaches in simulating and
modelling port operations for varying
purposes.
Marine ports are the interfaces be-
tween two modes of transport — land
and water. Ports are industrial areas
that are home to the interchanging of
cargo, information and funds among
different parties such as shippers, car-
riers, insurance companies, customs,
banks and stevedores.
Ports vary significantly in terms of
size, type of operation, location, man-
agement, type of equipment, layout and
many other aspects. Port managers are
aware of different factors affecting the
Visually modelling
a port
Captain Hossein.J.Kamali
smooth and efficient operation of mar-
ine terminals and utilize appropriate
models in supporting their decisions.
As within any operation, representa-
tion of the system plays a crucial role in
management. Representation can vis-
ually show how independent compon-
ents work and interact. It is important
to define the boundaries of the system
and it’s behavior which involves inputs,
processing and outputs.
Following illustrates a simple step
by step modelling of a port in a linear
format which is understandable for
non-experts.
It should be noted that flow of cargo
is not the only source of income for
ports, they charge their customers for
Figure 1. — Gate valve representation of
a simple port system.
As within any operation, representation
of the system plays a crucial role in
management.

2. April 2012 BC Shipping News 33
ports & terminals
a number of dues and services. No sys-
tem is truly linear and no man-made
model can suffice for decision-making
but should be viewed as a tool for an-
alysis and consideration. Visual rep-
resentation is easier to interpret than
straight text.
A simple way of representing a port
system is to identify a “gate valve”, also
known as a “sluice valve”, which operates
by lifting a gate/wedge out of the path of
the fluid, Figure 1. The fluid is the cargo;
the inlet and outlet of the valve are the
land and water transportation activ-
ities. The reservoir behind the gate valve
represents the storage yard and the gate
is an internal element affecting the
throughput of the port. When we com-
bine the valve with a reservoir a simple
cargo terminal is formed.
This type of schematic diagram is
standard for the logistics of many busi-
nesses, with raw material as input,
inventory being kept in storage and
product as output. In this simple model
the gate is playing an important role, it
restricts the flow of cargo and regulates
the rate of throughput.
Figure 2. — Three major subsystems of marine ports.
Figure 3. — Subsystems interacting with throughput of the port.
However, a real port system is far
more complex. Cargo movement can be
in both directions (import & export)
and there are many other elements
which can restrict the rate of through-
put, such as quay cranes, quay transfer
equipment, workers/unions, weather,
drafts, market, local legislation and
others. The flow is not restricted by
any single valve but by a series of
valves, which holistically determine the
throughput.
Thus the above simple system can be
used as a single building block which
can be anywhere from fully closed,
slightly open or fully open.
Marine Port Subsystems
Marine ports are composed of three
major subsystems as illustrated in
Figure 2: Quay (Berth); Yard; and Gate
and rail-head.
Quay
Quay is where the physical transfer of
goods from ship to shore and vice versa
takes place. Throughput governing ele-
ments include:
• Quay equipments such as cranes, con-
veyer belt and pipes which transfer
goods from ship to shore and vice
versa
• Berth’s length and depth which de-
cides the number and size of ships
that can be berthed simultaneously
• Security level which is a measure to
enhance the security of ship and port
facilities
• Berth’s traffic and labour staffing at
any given time

3. 34 BC Shipping News April 2012
ports & terminals
Yard
Yard is where inventory is kept. It’s
throughput is governed by:
• Material handling equipment
• Current capacity
• Wharfage
• Complexity of the documentation
process
Gate and rail-head
Gate and rail-head are where the
goods are cleared in/out by the Cus-
toms department and connection is
established with land transportation
by interchanging the goods with land
vehicles.
The diagram in Figure 2. is similar to
a pipeline where subsystems determine
the capacity of the whole; the system
throughput rate is determined by the
least open gate valve.
There are more closely interrelated
systems and players within the logistics
chain of the marine industry that affect
the throughput of the port, including
multimodal transportation, rival ports,
off-dock terminals, lighterage at an-
chor and ocean carriers as shown in
Figure 3.
The main core of the port itself is at-
tached to land transportation from one
side and approaching sea passage on
the other side.
It should not be assumed that any
gate valve in the above model works in-
dependently. Although complete clos-
ure of a single valve along the pipeline
stops the entire throughput, their vari-
ance is not independent but is continu-
ously under the influence of the other
components, passively and/or actively.
For example, a berth’s depth is pas-
sively under influence of the approach-
ing canal. It would be redundant to
dredge a berth more than draft limita-
tion of the approach passage. Elements
such as labour force, ports equipment,
type of vessels to service and berth
traffic volumes and patterns, actively
affect each other in a multilateral way.
The same applies for international
trade, regional trade, national legisla-
tion, ocean carriers and rival ports.
Limitation of a port’s storage cap-
acity encourages the use of off-dock
terminals, which in turn is affected by
the multimodal transport and custom
regulations.
National legislation such as the
Emission Control Area which urges the
use of more expensive fuel by ocean car-
riers can affect the pattern of their port
rotation in favour of or against rival
ports. Poor quay equipment would re-
quire ships with mounted cranes. Depth
limitation encourages cargo work at an-
chor (lighterage).
The diagram evolves to Figure 4. by
showing interrelationships between
building blocks as red arrows.
To avoid excessive visual complexity,
only basic interrelationships have been
shown.
We may conclude that ports are stra-
tegically located in the supply chain as
an interface in the flow of goods and
act as a platform for the exchange of
information. As a key link within the
supply chain, ports have to co-operate
with shipping agents, forwarders, off-
dock terminals, ocean carriers, port
authorities, shippers, rail/road/feed-
er operators, truckers, governments
and administrative services such as
Customs.
Challenges facing ports are not only
related to the periodic economic cycles
and fluctuations but also to the chan-
ges in the structure and organization
of the industry. Ports must be adapt-
able to these changes and become more
involved in the integration of supply
chains by changing their traditional
fragmented approach into an integrat-
ed system within which new roles and
relationships with other players are
defined.
A holistic dynamic model can help
tackle the numerous issues ports face
and can save considerable time and
money in design and decisions which
otherwise may lead to sunk costs.
Captain Hossein J. Kamali is an
accomplished Master Mariner with exten-
sive international training and work ex-
perience in ocean-going vessels, shipping,
logistics, port operations and container
management. He has authored several
books on these subjects. Captain Kamali
can be reached at h.kamali@shaw.ca.Figure 4. — The interrelationships show the evolution of the supply chain.
Challenges facing ports are not only re-
lated to the periodic economic cycles...
but also to the changes in the structure
& organization of the industry.