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1 INTRODUCTION
The process of assessing and ranking researched
technology may be supported by different methods
that are characterized by different levels of
advancement. While comparing technologies we can
take advantage of quality method as well as
quantitative method. The first one concerns the
identification of features that can influence the
implementation and commercialization effect. The
second one should be used to indicate relevant
attributes that explain the reasons of distinctions
between technologies. Methods used in practice are
usually the combination of quality and quantitative
altitude . In accordance to researches conducted all
over the world it is impossible to choose one method
that will be the most appropriate for technology
analysis. Moreover, we can observe the tendency to
make use of several methods in each proceeding.
There is no doubt that the evaluation and selection of
technologies are difficult issues. This is because of the
multidimensional nature of technology, which leads
to uncertainty and thus ambiguity of assessments
(judgments), formed by the experts participating in
researches that involve ranking (Goossens & Cooke,
1996), (Kaizer & Kuznetsov, 2014).
It is worth saying that in the context of multi-
criteria problems, the expert assessment performed by
the survey technique, is a convenient tool supporting
the selection of appropriate alternative. This type of
research allows to evaluate, rank and make selections
of the tested variants (Trakhtenberg & Solomakhin,
2013), (Thomas L. Saaty, 1990).
In reference to the organization of dredging works
at the harbour the choice of appropriate dredger and
consequently the relevant work technology is the
fundamental decision for whole enterprise, therefore
the author proposes to use the expert survey as a
technique to support the decision-making process. It
Expert Survey Method as a Technique to Support the
Decision
-making Process During Dredging Activity at
the Harbour
A. Kaizer
Gdynia Maritime University, Gdynia, Poland
ABSTRACT: Organization of the dredging works is a multi-faceted issue. The management of the dredging
process varies according to the location and it mostly depends on local conditions (Żak, 2014). The paper
presents the results of the expert survey which was structured on a questionnaire concerning the dredging
techniques in harbours. Respondents, that take part in the research, were experts from different nations,
working at the management levels in the enterprises associated with the dredging branch. The aim of the
proposed research was to support the selection of the appropriate dredger, the preparation of optimal work
technology and the verification of strategic decisions affecting entire project. Taking everything into
consideration the author proposes to use the expert survey as a technique to support the decision-making
process. It enables to take advantage of the wide knowledge and experience of experts to create the most
suitable dredging project.
http://www.transnav.eu
the
International Journal
on Marine Navigation
and Safety of Sea Transportation
Volume 14
Number 1
March 2020
DOI: 10.12716/1001.14
.01.23
188
enables to take advantage of the wide knowledge and
experience of experts to create the most suitable
dredging project in case of dubious modeling results
(Mitchell, Wang, & Khodakarami, 2013), (Guida,
Baroni, Cojazzi, Pinola, & Sardella, 1996), (Formela &
Kaizer, 2013), (Miedema & Becker, 1993).
2 METHOD OF RESEARCH
As part of the study on organization of dredging
works in harbours, an expert assessment was carried
out, using the questionnaire method addressed to
practitioners (Książek & Nowak, 2009).
Respondents, that take part in the research, were
30 experts from different nations, working at the
management levels in the enterprises associated with
the dredging branch. The aim of the study was to find
out which basic parameters affect the selection of
dredger and to prepare the ranking of the
organizational and technological aspects which have
the strongest influence on the efficiency of dredging
works in harbours (Smolarek & Kaizer, 2016). In
addition, the respondents have an opportunity to
share their observations, experiences and suggestions
related to the organization of these activities.
Statistical results of the study are presented in Figures
1- 9.
3 RESULTS OF SURVEY
In the first part of the questionnaire, which related to
the criteria affecting the choice of dredger, the
respondents emphasized that features which
influence the selection of dredging equipment most
strongly are: the type of land (83%), cubic capacity
planned for separation (69%) and the location of the
project (62%).This result shows that the most
important issue during the organization of dredging
works is to adjust the working technology to the
planned dredge area (Fig. 1, 2, 4). In addition, the
results of the survey, signalize that it is also important
to consider the ship traffic intensity (59 %) while
choosing the dredger (Fig. 3). This point has an
influence on work schedule organization and thus it
defines the effectiveness of the project
implementation (Lund, 1990). Respondents affirmed
that hydro-meteorological aspects and environmental
activities have an medium impact on the organization
of dredging works in harbours (Fig. 5, 6). This result
may arise from the general location of harbours in
industrial areas and most often at considerable
distances from the environmentally protected areas
(Smolarek & Kaizer, 2015), (Formela & Kaizer, 2013).
The resulting structure of the first part of the
expert assessment focused on parameters affecting the
choice of dredger for dredging works in harbours has
been presented in the collective diagram in Figure 7.
Figure 1. Assessment of the influence that the type of
bottom soil has on the choice of dredger, in the opinion of
experts.
Figure 2. Assessment of the influence that the location of
dredging works has on the selection of equipment for
dredging works in harbours, in the opinion of experts.
Figure 3. Assessment of the influence that ship traffic
intensity has on the choice of dredger for dredging works in
harbours, in the opinion of experts.
Figure 4. Assessment of the influence that the cubic capacity
planned for separation has on the selection of dredger for
dredging works in harbours, in the opinion of experts.
189
Figure 5. Assessment of the influence that neighboring
urban areas and ecological aspects have on the selection of
dredger for dredging works in harbours, in the opinion of
experts
Figure 6. Assessment of the influence that
hydrometeorological conditions have on the choice of
dredger for dredging works in harbours, in the opinion of
experts
Figure 7. Resulting structure of expert assessments about
parameters affecting the choice of dredger for dredging
works in harbours.
The second part of the questionnaire survey was
focused on the issues leading to the effectiveness of
dredging works in harbours. Respondents gave an
opinion that the most important factor for effective
dredging is the installed power of cutting devices and
suction pumps (29%). The experts also assumed that
relevant matter is the distance to the dumping area
and to the dump-site where the dredging soil is put
(26%). On the other hand, ship traffic intensity,
dredger’s own propulsion, it’s good maneuvering
characteristics and compliance of work progress with
the schedule, represent 14-16 % of entire influence on
the efficiency of the dredging projects in harbours
(Fig. 8).
Figure 8. The resulting structure of the experts’ assessment
concerning aspects that significantly affect the efficiency of
dredging works in harbours.
The last question in the survey was: "What type of
dredger is the most useful while dredging in
harbours?”. The respondents reported huge difficulty
with making a clear choice because they claimed that
this is a multi-criteria decision. Thus, the averaged
results given by the respondents according to their
own experience gained during the organization of
specific dredging works in the harbours, indicate that
trailing suction hopper dredgers are most often used
(28%). These vessels are self-propelled dredgers with
high excavation capacities in non-cohesive soils. In
second place came backhoe dredgers (25%), which are
best suitable for conducting dredging works at quays
and hard-to-reach areas. The next type which was
mentioned was cutter suction dredger (21%) which
enables to dredge hard soils and ones which are not
easily workable. However, work technology of this
type of equipment requires setting anchors to stabilize
the position of the milling cutter. Relating to cutter
dredgers, they often use the floating pipelines. This
feature can completely disqualify this type of vessels
from working in harbours’ areas because of heavy
obstruction of shipping. According to the survey, the
bucket ladder dredgers are the least often chosen
equipment for dredging (12%). At present, these types
of vessels are technologically obsolete due to low
efficiency parameters and lack of their own
propulsion. They also significantly impede ship traffic
because of the positioning system with anchor lines
(Fig. 9).
Figure 9. The resulting structure of the experts' opinions
about types of dredgers which are most useful during
dredging works in harbours.
190
4 CONCLUSIONS
An expert survey, performed as a questionnaire, was
conducted among the group of thirty experienced
respondents, associated with the dredging branch.
Relatively small number of respondents taking part in
the survey, resulted from difficulties with finding the
experts in this field and from the fact that there is only
a limited number of companies which are involved in
the matter of dredging works.
According to the survey results, it is worth
mentioning, that the most important features which
influence the selection of dredging equipment are
type of soil, quantity of dredging spoil and also
location and topography of harbportur. This
conclusion shows that during the organization of
dredging works, it is essential to adjust the working
technology to harbour basin. Moreover, in the survey
was signalized that it is also important to consider the
ship traffic intensity while choosing the dredger.
Taking everything into consideration, investing in
port infrastructure should be properly planned so as
to avoid obstruction of operation of terminals and
obstruction of ship traffic (Kaizer, Smolarek,
Krośnicka, & Ziajka, 2017).
The survey enabled to gain additional knowledge
in the situation of making a decisions about projects
with global conditions as well as it gave a statistical
values of the assessments concerning parameters required
in the studies containing multi-criteria analysis.
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