Tri Tjahjono

Optimization of movement of the aircraft on taxiway area

The purpose of this study is to develop model to optimize the movement of the aircraft on taxiway area. The optimization process is carried out on a number of flights over a period of time and is performed sequentially between one flight to the next flight with the principle of first come first served. Optimization is based on the principle of choosing the shortest path between the start and end of the movement of aircraft on the taxiway area, taking into account the holding time which may result due to avoiding any conflict in the taxiway area. The best path is the one with the minimum total taxiing time and holding time within a set of alternative paths. Set is determined by the shortest path principle. Optimization is limited by the maximum allowable holding time, as well as minimum separation distance between aircrafts on the taxiway area. The proposed algorithm is applied on an illustrative example of case of Balis Ngurah Rai Airport. Results show that the optimization model could provide a better total time than the one of current practice.

Transportation supply chain safety assessment based on Ro-Ro ferry shiphandling difficulty model approach

Maritime transportation is one of transportation modes in maritime logistics system through carriage of goods by the sea. Ro-Ro ferry is a type of ship used for connecting the roads or railways among islands separated by sea. The essential role of Ro-Ro ferry becomes an issue for the reliability of logistics system, especially in the section of transportation supply chain. Shiphandling is one function of the ship operation system and in nature considered as a complex system. Therefore, the difficulty in handling on such ship will determine the potential risk of accident and establish the reliability of such transportation supply chain. This paper elaborates the development model of shiphandling difficulty for Ro-Ro ferry by the use of AHP and fuzzy logic approaches for assessing the performance of logistics system through shiphandling performance. The simulation of model is presented and discussed. Finally, the conclusion is remarked.

The AHP FIS Ship Handling Model for Determining Ferry Transportation Safety

The operation of ship especially Ro-Ro ferry contributes much to support connectivity among islands for a country like Indonesia which has categorized as archipelago country. The reliability of Ro-Ro ferry operation will impact to the movement of cargo as well as passenger and later it could cause larger impact on the economic sustainability of region involved. The reliability of Ro-Ro ferry operation could be determined by operation function such ferry. One important function is ship handling function which consists of the interaction among human, technical, environment, management and weather. As the consequence to perform the objective of ship handling, the hazards might appear. It could be remarked that ferry accidents often occur during their service e.g. collision, grounding, sinking and contact. Such accident may be as part of the result of ship handling difficulty as part of ship handling function. Therefore, decision tool model based on the ship handling difficulty need to be developed. The first aim of this paper is to present the proposed ship handling model through the combination of Analytic Hierarchy Process (AHP) and Fuzzy Inference System (FIS). The second aim is to perform a simulation to compare the ship handling difficulty level for Ro-Ro ferry at several straits in Indonesia. The result of this research might be used by ship masters, shipping companies and port authorities to develop strategies in overcome the hazard of Ro-Ro ferries so the reliability of ferry operation could be maintained.