Study on the navigation capacity of the approach channel of Tianjin Port: Part 2

Authorship

Yang Xingyan, Professor & Ji Hua, Assistant Engineer, First Design Institute of Navigation Engineering, Li Wei & Liu Hong, Senior Engineers, Tianjin Port Group Ltd, China

Publication

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Part 1 of this article was originally published in edition 33 of Port Technology International. It is available for download at https://3.8.175.202 under journal archives.

Because of the complexity of port systems, especially due to the effects of many random factors involved such as the arrival time of ships etc., an effective method to evaluate the approach channel navigation capacity of a port is currently unavailable. This paper introduces a simulating model of complete port systems that includes the relevant factors such as ship, channel, berth and handling operation. By using this model, a study has been performed on the demand for the channel navigation capacity by Tianjin Port at various development stages.

Establishment of the simulation model

The simulation model was established in two steps. In the first step, computing techniques are used to convert the mathematic models of the subsystems and the system logic relations into a conceptual model of an integral system. Special simulation language GPSS/H and Proof Animation software, which are the products of Wolverine Software Corporation of USA, was then used to convert the conceptual model into the simulation model so that it could be run on the computer. Figure 1 shows the brief flowchart of the simulation model.

The model was validated by comparing the simulated results of Tianjin Port for the year 2004 with the actual statistics data. In order to study whether the channel will still be able to meet the demand of the port, further development of the simulation was performed for the following three cases:

Case 1: Tianjin Port operation in 2010

Case 2: Tianjin Port operation in 2020

Case 3: Tianjin Port operation beyond 2020

Simulation results

The calculation results of the Case 1 study shows that in the year of 2010, the average density of ships navigating through the approach channel of Tianjin Port will be 142.8 ships a day. Within the time of the year, the idle time of the channel (no ships in the channel) is only about 4.08 per cent of the total time of the year. There will be on average 6.81 ships at a time in the channel, and there will be at maximum 19 ships in the channel at a time. The distribution of number of ships in the channel is  shown in Figure 2.

The ship wait time for channel availability when entering or leaving the port is 1.71 h/ship on average. The frequencies of waiting times are shown in Table 1 (see overleaf).

Table 1 shows that among the 26,060 ships that navigate through the channel in one year, about 81.63 per cent of the total number of ships will wait for less than 2 hours for channel availability (including 34.65 per cent of ships that do not need to wait for the channel). Whereas the number of ships that have to wait for more than 11 hours only accounts for 3.06 per cent of the total number of ships.  The calculation results show that about 6.58 per cent of channel wait time is caused by the  insufficient width of the channel for two-way navigation, about 84.43 per cent of the channel wait time is caused by over density of ships (including the effect of ships turning in the main channel), about 3.50 per cent of channel wait time is due to waiting for favourable tidal levels, and about 3.45 per cent of the channel wait time
caused by some ships passing the converging point of the North Branch Channel and the Main Channel.

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