Applying Theory of Constraint to Identify the Constraint of Marine Transportation System
Ship Operation is a business activity that involves huge amount of costs. Several studies have been conducted to improve the efficiency of shipping cost. However, most of the researches are still reviewing the components of the sea transportation system partially, so that the resulting solutions are merely focus on local optimum. Theory of Constraint (TOC) is a multi faceted methodology that sees the system as a series of processes or events that are interconnected. Although it has been widely used in manufacturing, the application of TOC in the services sector, in particular the sea transportation system is still limited. This research aims to implement the concept of TOC to identify constraints that exist in the sea transportation system and determine the impact of any such constraint on the efficiency of the system. The study was conducted at PT. X as one of the providers of sea transport services. To identify constraints, this research has built a model of ship's arrival, a model of ship turnaround time, and Cost Utilization Diagram. In addition, this study used a simulation method combined with statistical tests based on linear regression. The results showed that TOC can be applied to identify the constraint in the sea transportation system. The main constraint which limits the efficiency of marine transportation system in PT. X is jetty capacity. The jetty limitation constraint impacts on the high cost of congestion, so PT. X must pay greater operational for organizing sea freight services. To overcome the constraints, Investments Efficiency Ratio which is the ratio between the reduction in cost compared to the cost of investment to increase capacity constraint has been built. The results showed that each unit of rupiah spent to increase the capacity of the jetty will result in a decrease in operating expenses of 2.3 units.