Simulation-based optimization for generating the dimensions of a dredged coastal entrance channel

Abstract

An entrance channel is dredged when its natural dimensions are not adequate to accumulate more and larger ships. Considering the reconciliation among costs, safety and efficiency and the complex relationship among channel type, navigable water level and sailing speed, a simulation-based optimization framework is proposed to optimize channel dimensions with limited dredging budget constraints in an integrated way. In this framework, the optimization program generates channel dimensions acceptable for safe navigation with budget constraints, and seeks an optimal balance between the dredging costs and navigation efficiency, including vessel waiting time and berth utilization. The simulation model evaluates the values of navigation efficiency measures considering the randomness and dynamics in ship operation. Finally, an application is given and the results show that the proposed framework is effective and helpful for optimizing the dimensions of the entrance channel. Moreover, the proposed modeling and solution methods are general and can be applied to the port basin, anchorage area as well.

A Simulation Model to Determine the Capacity of a Y-Type Waterway Intersection for a Real Seaport

“…Each shipload has a berth service time, which is estimated by the port authority's experience and collected historical data. In the simulation model, we used an exponential distribution with a mean berth service time to simulate the berth service time [1,12].…”

“…The total adverse weather days in our case study are 77 days/year. Therefore, 77 days/year are uniformly distributed through the period of one year in the simulation model as non-operational days [1,12,14].…”

“…After making more replications, we can perform some additional analysis that would allow us to make some useful interpretations of the output. Estimating a sufficient number of replications requires more computational effort by the modeler [1,12].…”

Simulation Modeling for Ship Traffic Flow in Entrance Channel

“…Recently, the rapid increase in the number and size of ships leads to further pressures on the entrance channels [1,2]. For example, the Senate Appropriations Committee appropriated $33.5 million to deepen and widen the Houston Ship Channel, which deepened the channel from 12.2 to 13.7 m and widened it from 122 to 162 m [3][4][5]; Guangzhou Port will invest $484 million to expand its 66.6 km entrance channel into two-way traffic for container ships of 100,000 deadweight tons (DWT) [6]. Considering the high costs to expand entrance channels, a tool or model is needed to help the designers to evaluate the capacity of entrance channel and then to determine when to expand the channel and to select the dimensions of the expanded channel.…”

“…In consideration of the stochastic characteristics of a port system, to explore the performance of integrated system, queuing theory is not applicable, and a simulation technique has to be used by simulating ship operations in and out of a port via entrance channels, e.g., a one-or two-way channel, especially a longer one-way channel with passing places [7,8]. To simulate the complex port system, the "process description method" or "object-oriented method" is considered to be appropriate and efficient [4,5,7]. Moreover, other important procedures, such as model verification and validation and simulation replication determination, should be conducted before productive simulation runs are started.…”