Proceedings of the Thirty-second (2022) International Ocean and Polar Engineering Conference
Shanghai, China, June 5–10, 2022
Copyright © 2022 by the International Society of Offshore and Polar Engineers (ISOPE)
ISBN 978-1-880653-81-4; ISSN 1098-6189

www.isope.org

Navigation Risk Assessment Based on 3D Ship Field for Restricted Zone in Zhoushan
Shuangshuang Xu ，Xiwu Gong，Yin Feng, Hu Pan

Zhejiang Ocean University, School of Naval Architecture and Shipping
Zhoushan, Zhejiang, China

ABSTRACTThe concept of the field of ships was first proposed by the Japanesescholar Dr. Yahei Fujii, and then received strong attention from manyscholars at home and abroad. At first, it was mainly based on statisticalmethods to quantify the field of ships with ellipses or irregular circles.
Now the emergence of intelligent methods has turned the ship field intoa dynamic area that can be adjusted according to different elements,
which can take into account various factors that affect the ship field,
such as people, ships, and the environment(TANG,2020). In waterway
transportation, the ship domain model has become an important
theoretical basis for research on ship collision risk assessment,navigation safety, collision avoidance decision-making, maritime
traffic capacity and channel planning and design (Liu,2011).

According to the traffic safety situation in the restricted sea area of
Zhoushan, this paper builds a three-dimensional dynamic ship fieldfrom the horizontal and vertical directions; then, on the basis of the shipdomain model, the three-dimensional space collision risk and timecollision risk sub-models are established. Additional risk weighting iscarried out for special cargo ships that are prone to accidents byinvestigating, collecting and analyzing accident data and ship dynamic
data; then, the risk degree of these three sub-risk factors iscomprehensively considered to establish a systematic comprehensive
evaluation model of navigable risk in Zhoushan restricted sea area andthe risk level of collision accidents; finally,the case of collision
between General cargo ships and fishing boats is used to verify this.
This model is innovative in the field of building three-dimensional
dynamic ships. In addition, not only the external risk factors but also
the additional risks in the transport of special cargo are considered in
the assessment of navigable risk. Compared with most of the othermodels, the three-dimensional dynamic field is used to calculate thecollision risk between ships which not only considers the hazard in thehorizontal direction, but also covers the hazard in the vertical direction
and has good integrity. The analysis of the results shows that thecollision risk degree obtained by the comprehensive assessment modelof navigation risk can effectively evaluate the collision risk degree ofthe ship during the course of traveling and can provide a reference forthe ship's collision avoidance decision-making and navigation safety.

Collision Risk Index (CRI) is a basic concept to measure the possible
degree of Collision between ships, and its value ranges from 0 to 1
(Mei J H,2019;Xu Wen,2017). The risk of ship collision can bedivided into macroscopic collision risk and microscopic collision risk.
The macroscopic collision risk can quantify the possibility of a ship
collision accident in a certain sea area. In the early days, most experts
and scholars used the number of collision accidents in water unit time
to characterize the macroscopic collision risk (Cockroft, A. N, 1981).
Goodwin E M (Goodwin E M, 1983) will consider this parameter in themodel when calculating the collision risk in a certain water area, andfinally obtain satisfactory results. Lewison G R G (Lewison G R G,1978) used a model to estimate the expression of the number ofencounters, and the model introduced traffic flow theory to make theevaluation results more realistic. Pedersen PT (Pedersen PT, 1995)
proposed the famous Pedersen model, which replaces the ship density
in the geometric collision probability model proposed by Fujii withtraffic flow and improves the model. To distinguish and compare,including encounter, cross and overtake three situations, systematic
analysis makes the model more reasonable and reliable. The microcollision risk is a measure of the likelihood that two or more ships willcollide. Kearon J (Kearon J, 1977) introduced two parameters, DCPA
and TCPA, into the model for the first time when obtaining theanalytical expression of the microscopic collision risk function basedon the model. Bukhari A C (Bukhari A C, 2013) added the relative
azimuth difference parameter as an input on the basis of the original
two parameters of DCPA and TCPA, which made the analysis results
more comprehensive. Bukhari A C (Bukhari A C, 2015) established aship collision risk model based on fuzzy theory and analyticalexpression, and obtained satisfactory results.Based on the theory ofship domain, this paper establishes three-dimensional collision risk andKEY WORDS:three-dimensional dynamic ship field; comprehensive
evaluation model of navigation risk; risk level; navigation safety

INTRODUCTION
Zhoushan sea area is one of the busiest sea areas in China, withYangtze estuary in the north and Xiangshan Bay in the south. With
the development of China's economy, zhoushan sea area has brought
unprecedented opportunities, limited zhoushan sea area will also face
the needs of navigation expansion and greater water traffic safety
challenges. The higher the traffic density of ships in different regions,the higher the collision risk. Due to the high risk of accidents, it isnecessary to carry out empirical studies on various risk factors affecting
traffic safety in Zhoushan sea area and put forward reliable quantitative
analysis methods (Chen,2020).

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