Research On Measurement Method Of Ship Service Efficiency Of Ports Based On AIS Data

Sea transportation plays an important role in global cargo transportation.As an important hub of sea transportation,the service efficiency of ports is related to the efficient operation of the whole supply chain system.Since the outbreak of COVID-19,some ports have experienced severe congestion and delayed detention,and container freight rates have risen sharply,which has drawn attention to the efficiency of port ship services.In the evaluation of world-class ports,it is difficult to make a horizontal comparison of ship service efficiency among ports due to the lack of unified evaluation index for ship service efficiency and the difference of data statistical caliber.How to select objective evaluation indexes and use unified measurement methods to reflect the service efficiency of ports to ships has become a common concern in the industry.Ship direct berthing rate and average anchorage waiting time are selected as the core indexes to evaluate the efficiency of port service to ships.By applying the massive data generated by Automatic Identification System(AIS).This thesis proposes a method for calculating ship direct berthing rate and average anchorage waiting time based on AIS data.The results are applied to the service efficiency evaluation of container hub ports.The specific research content includes the following aspects.(1)AIS data were preprocessed and port boundary was generated.AIS messages were decoded into data that could be used in practice,and an improved two-stage Layda criterion was proposed to eliminate outliers in AIS data for the purpose of AIS data cleaning.Aiming at the problem that it is difficult to obtain the boundary of the port area,based on the data of berth points,Arc GIS software is applied to expand the berth points of each area,and the latitude and longitude coordinate set of the port area boundary is obtained.In addition,AIS data,ship database data and boundary information of port area and anchorage were matched to obtain the complete AIS space-time trajectory of ships entering and leaving ports of different ship types.Compared with the data of container ships above 3000 TEU in AIS big data analysis system,the coverage of AIS data samples was maintained at more than 90%,proving the reliability of AIS analysis method and the advantage of full sample.(2)The calculation methods of ship direct berthing rate and average anchorage waiting time are constructed.By analyzing the time and space trajectory of ships entering and leaving the port,three kinds of behavior trajectories of ships entering and leaving the port are described completely,including berthing directly,anchoring and docking.According to three kinds of ship’s arrival dynamics,the judgment basis of ship’s direct berthing and not direct berthing is summarized.Based on the above work,the calculation methods of ship direct berthing rate and anchorage waiting time are established.Based on the AIS track data of ships entering and leaving the port,determine whether the ships are waiting in the anchorage and calculate the waiting time,remove the passing ships,ships entering the shipyard and other abnormal data,get the ships berthing at the berth,and then calculate the number of ships directly berthing.Calculate ship direct berthing rate and mean anchorage waiting time.Thus,the calculation methods of ship diret berthing rate and anchorage waiting time are constructed.(3)The calculation methods of ship diret berthing rate and anchorage waiting time are calculated by examples.The AIS data of the ships in and out of the sample ports were selected for calculation,and the direct berthing rate of container ships in different ports and the average waiting time at the anchorage were compared,and the direct berthing rate of container ships of different sizes in the same port and the average anchorage waiting time were compared.The results show that the ship service level of each port can be compared horizontally according to the calculation results of ship direct berthing rate and average anchorage waiting time,and the service level of the same port to ships of different sizes can also be compared vertically.Taking Tianjin Port as an example,the calculation results based on AIS data were compared with the direct berthing rate results published by the Port,which verified the accuracy and authenticity of the calculation method.The research results provide more objective and accurate data support for the evaluation of service efficiency of global ports.