Introduction

1.  Introduction

Management in container terminals deals with a dynamic system that has many factors and variables interrelated to each other. Some of them have stochastic behavior; therefore they need a tool to view the subsystems in an interrelated way (Henesey, 2006).

As described by Anderson et al. (2000), simulation is one of the most widely used quantitative approaches in decision making. It is a method for learning about a real system by experimenting with a model that represents the system. The simulation model contains mathematical expressions and logical relationships that describe how to compute the value of the outputs given the values of the inputs.

Next to simulation, there are analytical and some other operational research methods e.g. Fuzzy Analytic Hierarchy Process which can study the effect of qualitative and quantitative parameters, simultaneously. Many decision-making cases are too difficult to be understood only quantitatively. Evaluation of container stacking area layout in a container terminal depends on many other qualitative and to some extent imprecise information. Quantitative information obtained as the output of a simulation model should be taken in the consideration as seriously as qualitative aspects. MADM (multiple attribute decision making) methods can deal with these two kinds of data. Fuzzy set theory resembles human reasoning in its use of approximate information and uncertainty to generate decisions. It was specifically designed to mathematically represent uncertainty and vagueness (kahraman, 2004). The benefit of extending crisp theory and analysis methods to fuzzy techniques is the strength in solving real-world problems, which inevitably entail some degree of imprecision and noise in the variables and parameters measured and processed for the application (kahraman, 2009). Evaluation of container stacking area layout is one of these real word problems. This problem involves both quantitative aspects which can be calculated by simulation models and qualitative ones which can be obtained from expert's judgments. In this paper we will introduce two types of layouts for container stacking in port of Anzali, Iran. Layout A with horizontal stacks and B with vertical stacks, regarding to some fixed assumptions which will be described later in this study. This simulation study analyzes the loading process only to find out the effect of container stacking layout on travel time of the trucks and other terminal equipments. Then we will define other effective factors for evaluation of the layouts. Taking in the consideration the simulation outputs and other defined factors, finally we will prioritize these two layouts by the help of Extent Fuzzy AHP method. It is very important to find out how a special layout type can provide a better performance for a container terminal. A definite layout type has direct effects on terminal costs, quantity of equipment, man powers, safety of operations and etc. It also affects the productivity of container terminal sub-systems like: ship-to-shore sub-system, Transfer cycle and storage sub-systems (Chin et al., 2004). So, Evaluation of different layouts by precise methods helps terminal container managers to select an effective layout type. In this article a simulation model by the use of ''Show flow'' software is applied for analyzing the differences between performance indicators in two typical container terminal layouts. Two different layouts with vertical and horizontal stacks are considered to be compared according to ''management'', ''operational area'' and ''operational time'' as three main criteria.