Time efficiency assessment of ship movements in maritime ports: A case study of two ports based on AIS data

Abstract

Operational efficiency of a maritime port is an important issue for shipping lines and port authorities. It is desirable to move ships in and out of a maritime port as efficiently as possible. Automatic identification system (AIS) data recording the trajectory of ship movements allow us to assess the operational efficiency as ships move in and out of a port. This study proposes a time efficiency assessment framework that evaluates the amount of time each ship spends in the different areas within a port (i.e., berth, anchorage, and fairway) based on the space-time trajectories of ship movements derived from AIS data. According to the statistical distributions of time spent by different types of ship in each port area, the proposed framework can compare time efficiency across different zones within a port and between different ports. This study uses AIS data of four types of ships (i.e., container, cargo, tanker, and passenger ships) at two selected ports in China, Shanghai Yangshan Port and Xiamen Port, to demonstrate how the proposed approach can effectively assess and compare time efficiency levels of ship movements between the times entering and leaving the vessel traffic service (VTS) lines of a port. This study demonstrates the value of deriving space-time trajectories from AIS data based on the concepts of time geography to assess time efficiency levels of maritime ports and monitor their performance over time, which offer useful information to both shipping lines and port authorities for operations such as efficient scheduling and logistic support.

Introduction

Maritime transportation is an important part of international logistics. World seaborne trade volume expanded by 2.7% and the total volume grew to 11 billion tons in 2018 (UNCTAD, 2019). Cargo ships, tanker ships, and container ships ranked the top three among all ship deliveries in 2018, with cargo ships accounting for 26.7% of total gross tonnage, followed by tanker ships (25%) and container ships (23.5%) (UNCTAD, 2019). An estimate of 793.26 million twenty-foot equivalent units (TEUs) were moved at container ports around the world and global container port traffic increased by 4.7% in 2018 (UNCTAD, 2019). Furthermore, containerized trade increased by 2.6%, dry bulk trade increased by 2.6%, and global tanker trade increased by 1.5% in 2018 (UNCTAD, 2019). Although the main purpose of passenger ships is not for transporting goods and their share in dead-weight tonnage is negligible compared to container, cargo and tanker ships, passenger ships accounted for more than 11.9% of the fleet's market value in 2018 (UNCTAD, 2019). This large scale of maritime transportation contributes significantly to the development of world trade, global supply chain, and international economy. Efficiency of maritime port operation therefore is a core issue of maritime transportation in support of global trade flows.

Previous studies have focused mainly on operation efficiency at berth, while studies of the efficiency of other phases in a port (e.g., vessel traffic services (VTS) line-to-berth, berth-to-VTS line, and anchorage) are limited. Based on space-time trajectories of different types of ships derived from Automatic Identification System (AIS) data, it is possible to analyze the efficiency of ships undergoing various phases in a port. In addition, areas with low time efficiency of ship movements in a port can be identified, which enables port authorities to improve efficiency and provide better transportation services. This study uses AIS data of four types of ships (i.e., container, cargo, tanker, and passenger ships) at two selected ports, which are Shanghai Yangshan Port and Xiamen Port in China, to demonstrate how the proposed approach can effectively assess and compare time efficiency levels of container, cargo, tanker, and passenger ships from the point when they enter the vessel traffic service (VTS) line to the point when they leave the VTS line of each port. Major contributions of this paper are as follows:

• A space-time trajectory framework based on the concepts of time geography (Hägerstraand, 1970) is developed to assess the time efficiency performance of ship activities as they move through different zones from the point they enter the VTS line to the point they leave the VTS line in each port;

• A set of AIS-based time efficiency indicators is introduced to assess the operational performance of different types of ships (i.e., container ships, cargo ships, tanker ships, and passenger ships) that exhibit varying distribution curves of time efficiency; and

• A case study of two major ports in China, which are Shanghai Yangshan Port and Xiamen Port, demonstrates how the proposed AIS-based approach can effectively assess and compare the time efficiency patterns of different types of ships and of different ship sizes as they pass through different zones in each port.

The remaining parts of this article are organized as follows. The next section reviews previous research related to AIS data analysis and port efficiency assessment. The third section presents a proposed time efficiency assessment framework based on AIS data and the related methods. The fourth section discusses the two selected ports and the data used in this study as well as the analysis results derived from the proposed time efficiency assessment framework. The final section summarizes this study and offers some future research directions.