An Efficient Maintenance and Spare Parts Inventory Management

2012 IEEE International Conference on Vehicular Electronics and Safety July 24-27, 2012. Istanbul, Turkey
An Efficient Maintenanceቤተ መጻሕፍቲ ባይዱand Spare Parts Inventory Management Software for ITS Equipment
978-1-4673-0993-6/12/$31.00 ©2012 IEEE 334
time and spare part inventory, waste of time and fuel and a possible increase in pollutant emissions due to additional congestion caused by down-time of ITS equipment. One of the significant components of any maintenance system is being well-prepared for failures by ensuring availability of spare parts. Currently, many DOTs do not use a system to keep an active inventory of spare parts for their ITS devices. However, it is clearly stated in [2] that “a lack of spare parts inventories and difficulties in procuring spare parts in a timely manner” are two key concerns. First of all, it should be noted that some of these spare parts can be only replaced by the contractor, or original manufacturer. Anecdotal evidence has suggested that “the ability to get spare parts quickly is one of the most common reasons to rely on contract maintenance” [2]. However, many traffic operations units still have the responsibility of maintaining ITS equipment. Actually, regardless of the contracting method used, sufficient quantities of key parts should be available for maintenance. "Some agencies routinely keep on-hand a percentage of the original quantity as spare parts without using any mathematical model, but based on experience. Such an approach is considered to result in time-saving and reduces the downtime of expensive ITS devices" [2]. Moreover, over the past decade, there have been several manufacturers that have gone out-of-business all around USA, leaving agencies with no immediate sources for spares [3]. To mitigate these problems, a DOT maintenance plan should incorporate scrapping items and ensure that spares are anticipated. A trade-off between minimizing the cost for inventories and maximizing the efficiency should be achieved by modeling an inventory management system designed for spare parts. In a recent study conducted for NJDOT [4, 5], Rutgers Intelligent Transportation Systems (RITS) researchers successfully developed a state-of-the-art Intelligent Transportation Systems inspection and maintenance manual (ITSIMM) and Rutgers ITS inspection and maintenance software (RITSIMS). RITSIMS is currently being tested by the DOT. Over time, the research team expects to obtain substantial amount of data about the usage of the ITS equipment so that this information can be used as an input for the spare parts inventory management model presented in this paper [6]. Integration of the type of an inventory management system similar to the one described in this paper with the equipment history features of RITSIMS [4] will help traffic operations and maintenance personnel to improve their inspection and maintenance activities. II. THE SPARE PARTS INVENTORY MANAGEMENT PROBLEM There are a number of objectives that are sought by the DOT personnel in order to develop an efficient spare parts inventory management methodology. These objectives
H
K. Ozbay, Professor, Civil & Environmental Engineering Department, Rutgers University. 623 Bowser Road, Piscataway, NJ, 08854. (Phone: 732445-0579, Fax: 732-445-0577, email: kaan@) E. E. Ozguven, Graduate Research Assistant, Civil & Environmental Engineering Department, Rutgers University. S. Demiroluk, Graduate Research Assistant, Civil & Environmental Engineering Department, Rutgers University.
Kaan Ozbay, Eren Erman Ozguven, Sami Demiroluk

Abstract—Intelligent Transportation Systems (ITS) has two major sub-components that depend on each other namely, vehicles and infrastructure. For the whole system to perform optimally and safely, both vehicle and infrastructure sub-components of ITS should be operating without major disruptions. In this paper, we focus on the better maintenance of ITS equipment to maximize overall system performance. Long-term down time of ITS equipment due to the unavailability of spare parts will not only increase personnel and repair time requirements, costs of replacement parts but also might lead to increased delays, poor air quality and fuel consumption. Therefore, timely availability of the spare parts of essential components of ITS equipment is essential within the inspection and maintenance procedures of ITS. The proposed spare parts inventory control model in this paper can determine the optimum levels of the safety stocks under probabilistic failure and availability assumptions for components of various ITS equipment. When this inventory control model is fully integrated into Rutgers Intelligent Transportation Systems Inspection and Maintenance Software (RITSIMS) [1], it will allow its users to efficiently manage DOT’s ITS spare parts inventory using historic maintenance and inspection data that is being collected by respective databases of RITSIMS. I. INTRODUCTION ighly dense and complex roadway infrastructure carries heavy traffic of cars and trucks. One of the most effective ways of managing this commuter and freight traffic is through the use of integrated intelligent transportation systems technologies that that take advantage of efficient integration of vehicle and infrastructure systems. However, for the whole system to perform optimally and safely both vehicle and infrastructure sub-components of ITS should be operating without major disruptions. In this paper, we focus on the better maintenance of ITS equipment to maximize overall system performance. It is thus important to ensure that deployed ITS equipment works properly and efficiently. Unnecessary ITS equipment failures and malfunctions due to inefficiencies of inspection or maintenance can create many problems [1]: increase in maintenance expenditures, shortening of the useful life of the ITS equipment, increase in requirements for personnel