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Although many new approaches have been developed in facilities design, the Systematic Layout Planning procedure still appears to be widely used particularly for container terminal layout design. This paper presents a revised Systematic Layout Planning which can address some of the limitations on its application for Container Terminal System (CTS) layout design. The limitations are: (1) SLP lacks a method to use containers handling routings as input data, and (2) it does not have the ability to generate layouts that are a hybrid combination of functional and cellular layouts for CTS. SLP is based on aggregation of an Activity Relationship Chart and/or a From-To-Chart into an Activity Relationship Diagram. This is followed by the determination of the amount of space to be assigned to each activity and the availability of space for CTS. Flow Analysis can be used to identify causes of delay in containers flows such as complex operation sequences at CTS, high volume, variety of equipments, ineffective facility layout, and inappropriate assignment of equipments for operations.
This study suggest that the integration of flow analysis in the enhanced SLP for CTS can be done to achieve a better layout design methodology. Moreover, using SLP with flow analysis approach can provide a higher flexibility to cope with fluctuations in process.
Keywords: Flow Analysis, CTS, and SLP.
The layout of a container terminal could be significant factors in the productivity of the container handling operations. For the operations, there are factors from container layout design that affected the productivity such as containers location, operations costs, equipment utilizations, and shipment schedules in conformance with fluctuation demand. For designing the layout of container yard, the outline of the yard, type of layout, and the number of aisles (rows and columns of blocks) must be determined. The design of a container terminal can be follow a specific structure called Systematic Layout Planning (SLP). SLP (Muther, 1973) is an organized way to perform layout design. SLP consists of a pattern of step-by-step procedures for layout planners to perform, and a set of conventions for identifying and evaluating various activities and alternatives involved in any layout design procedure. This paper focuses on two of the following limitations of SLP for Container Terminal System (CTS) layout design: (1) SLP lacks a method to use containers handling routings as input data, and (2) it does not have the ability to generate layouts that are a hybrid combination of functional and cellular layouts for CTS. The preferred alternative to implement the SLP procedure for CTS is should be sequentially to develop a block layout first and then a detailed layout for each planning yard. In the latter application, relationships between blocks, container locations and entrances to and exits from the yards are used to determine the relative locations of operations.
As stated by Muther (1973), "â€¦ in process-dominated industries often the most significant aspect of layout planning is Flow of Materials. â€¦". Material flow analysis is the heart of layout planning where movement of materials is a major portion of the process. SLP uses the From-To Chart (FTC) as the input for material flow analysis. In container terminal system, there is a situation that necessitates yards splitting, such as a cellular layout, then it may be more appropriate to use the original operation sequences from which the FTC was generated. Our research extends current thinking on input data requirements and methods for CTS facility layout. In addition, it supports the need for a new generation of CTS layouts beyond the optimal layouts that continue to be studied and implemented in CTS.
This paper is organized as follows: The literature on container terminal system and design of facility layout is reviewed in the second Section. In Section 3, a procedure for the arrangement of container terminal layout using SLP with flow analysis is presented. Section 4 shows the analysis on container terminal layout design and the optimization process of containers handling. Finally, Section 5 gives some concluding remarks for the implementation of SLP for CTS layout design.
2. LITERATURE REVIEW
Generally, facility layout has been formally studied as an academic area of research since the early 1950s. Balakrishnan and Cheng (1998), Meller and Gau (1996a), and Kusiak and Heragu (1987) have provided many good review papers were presented in literature. However, we focus on papers that are pertinent to the design of layouts in container terminal and type of layout using SLP.
2.1 Systematic Layout Planning
Facility layout design determines how to arrange, locate and distribute the equipment and support services in a manufacturing facility to achieve minimization of overall operations costs, maximization of operational efficiency, maximization of turnover of work-in-process and maximization of factory output in conformance with production schedules.
Systematic Layout planning (SLP) is based on aggregation of an Activity Relationship Chart and/or a From-To-Chart into an Activity Relationship Diagram. This is followed by the determination of the amount of space to be assigned to each activity and the availability of space for it. Based on modifying considerations and practical limitations, a number of layout alternatives are developed and evaluated. The preferred alternative is then implemented. The SLP procedure can be used sequentially to develop first a block layout and then a detailed layout for each planning department. In the latter application, relationships between workstations, storage locations and entrances to and exits from the department are used to determine the relative locations of activities. SLP uses the From-To-Chart as the input for flow of materials analysis.
Figure 1. The systematic layout planning design process (Muther, 1973)
Reviews of the earliest papers on From-To Charts (also referred to as Cross Charts) are provided by (Buffa, 1955; Cameron, 1952; Farr, 1955; Smith, 1955; Lundy, 1955; Weiss and Smith, 1955; Schneider, 1957; Bolz and Hagemann, 1958; Llewellyn, 1958; Cameron, 1960; Reis and Andersen, 1960; Schneider, 1960). In addition, the earliest textbooks on Facility Layout by (Apple, 1950; Immer, 1950; Muther, 1955) were studied. Based on these studies of the history of the From-To Chart, it was concluded that the use of the From-To Chart as the primary input for facility layout was driven by two factors in the 1950's which are: (1) The need to keep the problem size small to facilitate manual analysis (the number of departments in a large facility could range from 20-50 whereas the number of unique product routings could range from 250-5000), (2) the vast preference for the functional layout in industry at that time.
2.2 The Layouts of Container Yard
The facilities provided in a container terminal could be roughly divided, according to their functions, into the apron, the yard and supporting facilities (office and operations building, entrance gate, maintenance, etc.). A Container Yard (CY) should provide enough space for container marshalling, stacking and passages, appropriate to the handling system adopted. The CY is divided into several blocks each separated by access aisle ways. Containers are stacked in rows either perpendicular or parallel to the quay wall. The flow operations are from vessel unloaded by Quay Crane (QC), transported via Yard Truck (YT) from quay to yard, and than placed in a stack in the yard by Rubber Tire Gantry (RTG). The other pattern is for loading process, which is the opposite direction from unloaded process.
Figure 2. Container terminal operations
2.3 Production Flow Analysis
Production Flow Analysis (PFA) is a set of methods that helps manufacturers to identify causes of delay in material flows such as complex operation sequences, high volume and variety of parts, variety of machines, ineffective facility layout, and inappropriate assignment of machines for operations (Irani and Huang, 2000). They stated that when applied to a single factory, the classical framework for manual implementation of PFA consists of four stages, each stage achieving material flow reduction for a progressively reducing portion of the factory: Factory Flow Analysis (FFA), Group Analysis (GA), Line Analysis (LA) and Tooling Analysis (TA), which can be automated by a set of algorithms that they have been developed. In FFA, dominant material flows between shops (or buildings) are identified. In addition, if parts are observed to backtrack between any of the shops, these flows are eliminated by a minor redeployment of equipment. FFA may often be redundant for a factory that essentially consists of a single machine or fabrication shop. In GA, the flows in each of the shops identified by FFA are analyzed. GA analyzes operation sequences of the parts being produced in a particular shop to identify manufacturing cells. Loads are calculated for each part family to obtain the equipment requirements for each cell. Each cell usually contains all the equipment necessary to satisfy the complete manufacturing requirements of its part family. Due to sharing and non-availability of equipment, some intercell material flows and flows to/from vendors may arise. In Line Analysis (LA), a linear or U-layout is designed for the machines assigned to each cell. The routings of each part assigned to the cell and the frequency of use of each routing are used to develop a cell for efficient transport as well as minimum material handling and travel by operators. In Tooling Analysis (TA), the principles of GA and LA are integrated with data on the shape, size, material, tooling, fixturing, etc. attributes of the parts. TA helps to schedule the cell by identifying families of parts with similar operation sequences, tooling and setups. It seeks to sequence parts on each machine and to schedule all the machines in the cell to reduce setup times and batch sizes. This increases available machine capacity on bottleneck work centers in the cell.
3. PROCEDURE SLP WITH PFA FOR CONTAINER TERMINAL
As discussed earlier, the classical framework of SLP is inadequate for design of job shop layouts due to container terminal layouts. The two limitations in the stage of flow of containers handling analysis are: (a) incapability of using container operation routings, instead of the from-to chart, as input data, and (b) incapability of generating layouts that are a hybrid combination of functional and cellular layouts for determining container location in the yards. Adoption of principles of PFA in this stage can eliminate these limitations. Figure 3 shows the enhanced SLP design process after incorporation of PFA into the classical framework of SLP for container terminal layout design.
Figure 3. Systematic layout planning with flow analysis for container terminal
4. SLP FOR CONTAINER TERMINAL LAYOUT DESIGN
The decision issues for the CTS layout are as follows: (1) to decide the layout type of the yard; (2) to determine the outline of the yard, which is represented by the containers location in each blocks area; (3) to determine the number of driving aisles (lanes), equivalently, the length of blocks in the yard. As the space area of blocks becomes shorter, meaning that the containers should be on right locations (not just as first in first out); and (4) the expected travel distance and cost of trucks should be reduced. However, for good placement, it can be using Group Technology approach as a solution (Sugiyono and Abdekhodaee, 2009). To stack containers in a same area, the stacking location must be decided, which better results in a higher number of relocations during retrieval operations. Thus, there must be an economical length of a block that minimizes the total handling cost.
4.1 The Limitation of From To Chart for Container Terminal Layout Planning
In a typical facility layout project, initial (raw) data consisting of (a) the departments in the facility and the approximate area of each department, and (b) the operation sequences and batch quantities for the parts (or products) being produced in that facility is obtained. This data is transformed into a FTC. This chart captures the cumulative volume of material flow between any pair of departments. For CTS the departments are the block areas of yard for stacking the containers, products are the containers it's self, and it's also have an operation sequences and batch quantities. In the ideal case, if the operation sequence of each container in the sample of containers used to generate the FTC is decomposed into moves between consecutive pairs of blocks, then each of these moves should be between two adjacent blocks. However, in the container terminal layout designed using a FTC, several flows will occur between non-adjacent blocks i.e. blocks that do not share a common schedule of shipment. Unfortunately, in the process of aggregating all the operation sequences into a FTC, the routings of the individual containers are lost i.e. containers for SIBO shipment.
Table 1. Operation Sequences and Batch Quantities of containers handled in the CTS
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4.2 Systematic Layout Planning With Production Flow Analysis
The pioneering method for designing facility layout in combination with the material flow network was introduced (Irani, et.al, 2000). They developed programme library that provided an effective capability for analyzed the material flows at different levels of resolution in facility. For CTS layout design, it's need a consideration of modifying : (1) deciding the layout type of the yards, (2) determining the outline of the yard, which is represented by the containers location in each blocks area, and (3) determining the number of driving aisles (lanes), equivalently, the length of blocks in the yard. Types of layout for CTS are parallel and perpendicular layout (Kim, et.al, 2008). The type of yards layout should be determine first because it can be affected to the containers handling process i.e. to determine the driving aisles of RTGs and trucks. The outline of the yard should be determined for locating the containers in blocks area. This process represented by Group Technology (GT) in the yard planning stage. Finally, the length of blocks in the yard should be determined. As the length of blocks becomes shorter, meaning that the number of aisles increases, the expected travel distance of trucks can reduced. Below is the layout design problem in Indonesian Port Terminal that solved yard planning problem with using GT algorithm. This arrangement increased 10% of efficiency in container handling distances (Sugiyono and Abdekhodaee, 2009).
Figure 4. Comparation of containers location based on GT algorithm. (a) The initial layout. (b) Layout based on GT algorithm. (c) Handling route
4.3 Feasibility Evaluations of Planned Yards
The evaluation process for this method divides into two steps: feasibility evaluation and optimization. The first step will be regarding on uncertainty demand of each shipment schedule. A new challenge in CTS operations is ascended, which is the handling of mega vessels with a capacity of more than 10,000 TEU. This would be needed a flexibility arrangement of facility layout. One of the flexibility criteria is robustness. Robustness can be used in case of uncertainty environments. The uncertainty involved in the container terminal layout is mainly due to the same operations sequence of handling the containers. This also connected with the schedule of shipment and containers operation demand. Thus, different combinations of containers handling sequence would result in relationship diagram of flow. Relationship diagram of flow described that from different shipment, it can be a same sequence and same use of equipments (RTGs and trucks).
Second evaluation process is the optimization. There are six tools that can be used to evaluate the alternatives layout to select the final one. This referred to the effects of the design variables on the expected containers handling distance and the expected number of containers position in the yards. For the distance variable, total adjacencies score, handling distance, and handling cost are used for evaluate. For the expected number of containers position in the yards, simulation, capacity scheduling, and other multi criteria decisions can made. Table 2 suggests that, to implement a SLP with flow analysis, operation sequence would have to be duplicated in each of them. However, it is indicates that gate is always the origin point and point (a) is always as a final destination. Therefore, it may be possible to design a hybrid layout for blocks arrangement where all operations retain in same process. Table 3 shows that for design evaluation at least four scenario's can be made which are small terminal with less equipments, small terminal with more equipments, large terminal with less equipments, and large terminal with more equipments. Suppose that the number of columns in a yard-bay is open planning. Because the average height of stacks is 3 tier, as the retrieval of yards progresses, the number of blocks increases.
Table 2. Terminal capacity and handling distances
Table 3. Data's scenario for CTS
Table 4. Capacity's requirements planning for CTS
This paper proposes a method for planning yard position at container terminal. Systematic layout planning for container terminal is considered. The method comes up with modified step for yard planning and its evaluation. Procedures for optimizing layouts of container yards are suggested. It was discussed how to determine the layout type of container yards, the outline of the yard, and the evaluation process.
For evaluating the alternatives layout, this study proposed a method for estimating the expected number of relocations for yard planning from a given layout of the yard. Illustrations of evaluation steps were provided using data from actual container terminal at Indonesian Port Terminal. The results of the analysis showed that the layout results (using GT algorithm) in a shorter expected travel distance for the same layout gives some increasing efficiency. This study also assumed that for the capacity of the yard is open planning. However, other configurations of yards may be observed in practice. Also, it was assumed that the gate is located in the middle of the rectangle, which is an ideal assumption. The issues such as the effects of the location of the gate and various yard conditions may be addressed in future studies for evaluations.