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Showing papers on "Fleet management published in 2003"


Journal ArticleDOI
TL;DR: The literature on real-time vehicle routing is still disorganized and some issues that have not received attention so far are highlighted in this paper, where a particular emphasis is put on parallel computing strategies.

332 citations


Journal ArticleDOI
TL;DR: This work considers stochastic vehicle routing problems on a network with random travel and service times and provides bounds on optimal objective function values and conditions under which reductions to simpler models can be made.
Abstract: We consider stochastic vehicle routing problems on a network with random travel and service times. A fleet of one or more vehicles is available to be routed through the network to service each node. Two versions of the model are developed based on alternative objective functions. We provide bounds on optimal objective function values and conditions under which reductions to simpler models can be made. Our solution method embeds a branch-and-cut scheme within a Monte Carlo sampling-based procedure.

302 citations


Journal ArticleDOI
TL;DR: An overview of several important areas of operations research applications in the air transport industry, including the various stages of aircraft and crew schedule planning; revenue management; and the planning and operations of aviation infrastructure (airports and air traffic management).
Abstract: This paper presents an overview of several important areas of operations research applications in the air transport industry. Specific areas covered are: the various stages of aircraft and crew schedule planning; revenue management, including overbooking and leg-based and network-based seat inventory management; and the planning and operations of aviation infrastructure (airports and air traffic management). For each of these areas, the paper provides a historical perspective on OR contributions, as well as a brief summary of the state of the art. It also identifies some of the main challenges for future research.

297 citations


Patent
02 Oct 2003
TL;DR: In this article, a fleet management system manages a plurality of machines (i.e., a fleet manager includes a communication conduit (104) coupled to the machines (102) for receiving status information and a repository (106) coupled with the communication conduit for receiving and storing the status information.
Abstract: A fleet management system manages a plurality of machines (102). The fleet manager includes a communication conduit (104) coupled to the machines (102) for receiving status information related to the machines (102) and a repository (106) coupled to the communication conduit (104) for receiving and storing the status information. The system also includes a fleet manager controller (110) coupled to the repository (106) for analyzing the status information.

119 citations


Journal ArticleDOI
TL;DR: In this paper, a simulation engine for estimating the time and cost of this class of projects considering different practical scenarios is presented, and the simulation engine is implemented in a Microsoft environment to facilitate integration among its components.
Abstract: This paper presents a simulation engine, developed to model earthmoving operations. The engine has been designed utilizing object-oriented features, and it represents a main component in a newly developed automated system for selecting a near-optimum fleet configuration. It provides contractors with a vehicle for estimating the time and cost of this class of projects considering different practical scenarios. The system has been implemented in a Microsoft environment to facilitate integration among its components, which have been developed in the same environment. The paper focuses on the modeling aspects of the simulation process using discrete event simulation and object orientation. A numerical example of an actual case is analyzed to validate the developed simulation engine and demonstrate its capabilities. The results are compared to those generated using Caterpillar software (FPC). The engine and FPC recommended the same fleet and their estimated project durations were very close, with a difference less than 8%. Unlike FPC, the developed engine, however, can model and account for uncertainty during the execution of earthmoving operations in a reliable manner.

95 citations


Patent
27 Aug 2003
TL;DR: In this article, a method of managing power cell information resources of a non-petroleum fueled vehicle, particularly electric or fuel cell vehicles of a fleet of vehicles, is presented.
Abstract: A method of managing power cell information resources of a non-petroleum fueled vehicle, particularly electric or fuel cell vehicles of a fleet of vehicles. Such vehicles have power pack instrumentation for wirelessly reporting data to a base station computer including power pack charge parameters and GPS location in real-time. This data is applied to a database which documents past vehicle performance as well as contains minimal acceptable vehicle parameters. A prediction is made regarding remaining range, state of charge and vehicle scheduling, considering vehicle load or mileage efficiency. The remaining range is viewed in combination with the GPS location of the vehicle so that judgments can be made regarding whether particular vehicles can take a job request, complete the job without recharging, then go to a recharging location, or have the vehicle dispatched for service.

92 citations


Patent
04 Apr 2003
TL;DR: In this paper, a system and method of centralizing traffic signal preemption for roadway emergency operations provides for increased accuracy and coordination of emergency response vehicles along an emergency route, i.e., a centralized preemption system receives status and location information from emergency vehicles via fleet management systems or dispatch centers.
Abstract: A system and method of centralizing traffic signal preemption for roadway emergency operations provides for increased accuracy and coordination of emergency response vehicles along an emergency route. A centralized preemption system receives status and location information, e.g., GPS, from emergency vehicles via fleet management systems or dispatch centers. As an emergency route is determined and projected in real-time, predetermined policies are applied to create an overall preemption plan of traffic lights at intersections along an anticipated route. The preemption plan results in preemption directives being transmitted to traffic management systems that are controlling traffic signal controllers at intersections along the route. The centralized preemption system may coordinate among many traffic management systems that provides for a much larger preemption service area including multiple jurisdictions.

59 citations


Patent
28 Apr 2003
TL;DR: In this paper, a system for managing vehicle reservations, vehicle assignment and vehicle access is presented, which enables a rental vehicle or car sharing agency (i.e., or for that matter, a vehicle fleet management service or other similar entity) to assign vehicles to users of the vehicles in accordance with previously received reservations vehicle information, and other information.
Abstract: A system, including apparatuses and methods, for managing vehicle reservations, vehicle assignment, and vehicle access. The system enables a rental vehicle or car sharing agency (i.e., or for that matter, a vehicle fleet management service or other similar entity) to assign vehicles to users of the vehicles in accordance with previously received reservations vehicle information, and other information, and enables the users to pickup the vehicles for their use, without interaction with agency personnel.

58 citations


Patent
08 Apr 2003
TL;DR: In this article, an asset management platform (AMP) processes messages from mobile assets (112A-112C) to enable data-driven monitoring and management of the assets, using state information and other data stored in a database.
Abstract: An asset management platform (AMP) (100) processes messages from mobile assets (112A-112C) to enable data-driven monitoring and management of the assets (112A-112C) The mobile assets transmit messages to the AMP specifying the asset's current locations and other information Modules in the AMP normalize and augment the messages using state information and other data stored in a database A router routes copies of the messages to multiple destinations (114), including applications and a business operations middleware (BOM) module The BOM includes queues for holding messages of different types and subscribers for processing the messages in the queues An event-action subscriber processes messages as specified by event-action rules The event-action rules provide flexible and extensible asset tracking (116A-116C), fleet management, and notification capabilities

43 citations


01 Jan 2003
TL;DR: In this paper, the authors provide a useful summary of practice in the area of commercial truck and bus safety management techniques, including driver recruiting and selection, carrier-based training, management-driver communications, driver safety-performance evaluation, safety incentives, behavior-based safety, on-board safety monitoring, event-data recorders, accident investigation, improved driver scheduling and dispatching, fatigue management, carrierbased medical programs, preventive maintenance and vehicle inspection, advanced safety technologies, and industry-based certification.
Abstract: This synthesis will be of use to commercial truck and bus carriers and others interested in improving commercial vehicle safety. It provides a useful summary of practice in the area of commercial truck and bus safety management techniques. The synthesis focuses on the problems fleet managers confront and the methods that are available to address these problems. Twenty discrete safety problems and 28 safety management methods are identified. Problems addressed encompass driver-safety knowledge, skills, alertness, physical/medical condition, attitudes, and driving behaviors. In addition, several vehicle-related problem areas, including vehicle maintenance and inspection, are discussed. Major safety management approaches addressed include driver recruiting and selection, carrier-based training, management-driver communications, driver safety-performance evaluation, safety incentives, behavior-based safety, on-board safety monitoring, event-data recorders, accident investigation, improved driver scheduling and dispatching, fatigue management, carrier-based medical programs, preventive maintenance and vehicle inspection, advanced safety technologies, and industry-based safety standards and certification. The synthesis is based on a review of relevant literature, as well as a survey of commercial motor vehicle safety managers (139 respondents) and other experts in motor carrier safety (57 respondents).

39 citations


Journal ArticleDOI
Liping Fu1
TL;DR: This model was shown to have a strong explanatory power, capable of capturing the complex relationship between fleet size, travel demand, quality-of-service measures, and other operating condition variables.
Abstract: An analytical model could potentially be used by paratransit service planners to predict fleet requirements, system capacity, and quality-of-service measures for specific operating conditions. The model has a sound theoretical origin and was calibrated using data from a large number of simulated cases representing a wide range of operating conditions and quality of service. This model was shown to have a strong explanatory power, capable of capturing the complex relationship between fleet size, travel demand, quality-of-service measures, and other operating condition variables. With this model, analytical procedures similar to those provided in the Highway Capacity Manual and the Transit Capacity and Quality of Service Manual for other transportation facilities and services could be developed for paratransit systems.

Journal ArticleDOI
TL;DR: Bitwise Solutions developed a flexible, integrated decision-support system to help fractional management companies optimize their fleet schedules and succeed, called FlightOps, which handles all aspects of fractional fleet management: reservations, scheduling, dispatch, aircraft maintenance, and crew requirements.
Abstract: Fractional aircraft ownership programs have revolutionized corporate aviation. For a fraction of the cost, they offer owners the comfort and convenience of a full-time flight department. However, fractional management companies (FMCs) have costly business requirements that neither commercial airlines nor charter airlines face. Two challenges that affect their profitability are (1) the management company, instead of the customer, pays all positioning costs, and (2) FMCs give owners short call-out windows, sometimes as little as four hours before departure and guarantee lift to satisfy their demands. FMCs must operate their fleets efficiently. Bitwise Solutions developed a flexible, integrated decision-support system to help FMCs optimize their fleet schedules and succeed. The system, called FlightOps, handles all aspects of fractional fleet management: reservations, scheduling, dispatch, aircraft maintenance, and crew requirements. It also keeps track of the FAA regulatory requirements for crew duty. The system includes the ScheduleMiser, a CPLEX-based decision-support tool. ScheduleMiser creates an optimal schedule for a fleet of aircraft and a set of owner demands (missions) by minimizing costs while meeting FAA regulations and FMC business rules for feasibility. The mixed-integer model behind ScheduleMiser allows FMCs to manually schedule many types of restrictions on an aircraft's schedule, including maintenance periods, flight restrictions, and manual mission assignments. If an aircraft is not available to fly a mission, the FMC can schedule a comparable or larger available aircraft within its fleet, or it can subcontract a charter aircraft. In November 2000, Raytheon Travel Air, the second largest FMC, started using FlightOps. In a press release, it stated FlightOps helped it produce record numbers in hours flown and aircraft availability over Thanksgiving week 2000. It reported an 18.7 percent reduction in positioning legs for some aircraft and a $4.4 million savings in the first year after implementing our system.

Journal ArticleDOI
TL;DR: This paper presents an ASP to coordinate and disseminate tasks and related information for solving the vehicle routing problem using appropriate metaheuristic techniques and involves a Java Web applet equipped with interactive communication capabilities between peripheral software tools.

01 Jan 2003
TL;DR: How many fleet management systems use macros, or user-defined commands, that prompt drivers to input information are described, which can provide vehicle location and information, and can speed up internal processes such as billing.
Abstract: This article looks at wireless fleet management systems, describing how wireless communication systems can offer commercial vehicle operators the ability to monitor a wide range of driver and vehicle performance in real time. These systems can provide vehicle location and information, and can speed up internal processes such as billing. The article describes how many fleet management systems use macros, or user-defined commands, that prompt drivers to input information. Geofencing and automated messaging are also discussed as recent enhancements designed to limit manual and routine communications, and lead to greater efficiency and reduced costs.

Journal ArticleDOI
TL;DR: A new economically sound methodology for assisting with equipment replacement at Texas DOT that takes full advantage of Texas DOT’s comprehensive equipment operating system database, can prioritize the units on the basis of comparisons among all units within any desired class of equipment, and uses life-cycle cost trends as a replacement criterion.
Abstract: The Texas Department of Transportation (DOT) owns and maintains an active fleet inventory of approximately 17,000 units and replaces about 10% of them annually. Any methodology that can improve Texas DOT's replacement procedures could potentially save millions of dollars. Private and public agencies do not routinely use life-cycle cost as a replacement criterion because the only way to automate inspection of thousands of life-cycle cost histories has been to define an acceptability threshold for annualized costs. Most fleet managers consider this practice too inaccurate. The most relevant information provided by a lifecycle cost graph is its trend. Units whose life-cycle costs have been increasing longer or at a faster rate should have higher replacement priority. The trend score concept allows a computer to mimic replacement decisions made by a person visually inspecting a series of life-cycle cost histories. A new economically sound methodology for assisting with equipment replacement at Texas DOT is pr...

Journal ArticleDOI
TL;DR: In this paper, an asset management framework is presented that can be used by state departments of transportation to allocate capital dollars for the dual purpose of purchasing new buses and rebuilding existing buses within the constraints of a fixed budget when the needs of all constituent agencies in a peer group are considered and distribute funds among the agencies equitably.
Abstract: State departments of transportation that provide the bulk of matching funds to local transit agencies for the purchase of new buses are duly concerned about the escalating costs of new buses and the lack of sufficient funds to keep up with their replacement costs. An asset management framework is presented that can be used by state departments of transportation to (a) allocate capital dollars for the dual purpose of purchasing new buses and rebuilding existing buses within the constraints of a fixed budget when the needs of all constituent agencies in a peer group are considered and (b) distribute funds among the agencies equitably. The proposed framework includes two optimization models. Model 1 attempts to maximize the weighted fleet life of all the buses being purchased and rebuilt for a given peer group within the constraints of a fixed budget. Model 2 is designed to maximize the remaining life of the entire peer group, including the existing buses and those being replaced or rebuilt. Case studies presented to demonstrate the application of the models show that the framework is viable and can be used for the designated purpose with fleet data currently available from transit agencies. Further research on testing the framework is recommended to ensure its applicability under different sets of circumstances.

Journal Article
TL;DR: In this paper, the authors discuss how local governments, using successful strategies employed by private fleet companies, can improve efficiency and cut costs related to operation of their public works vehicle fleets.
Abstract: This article discusses how local governments, using successful strategies employed by private fleet companies, can improve efficiency and cut costs related to operation of their public works vehicle fleets. The focus is on implementing best practices in order to attain a higher level of organizational function.

E Meyer1, I Ahmed
01 Jan 2003
TL;DR: In this paper, the authors report on a study of the use of automatic vehicle location (AVL) for highway maintenance activities, especially snow removal, and find that only eight states had deployed AVL, in addition to several municipalities and one Canadian province.
Abstract: This paper reports on a Kansas study of the use of automatic vehicle location (AVL) for highway maintenance activities, especially snow removal. State departments of transportation and other transportation agencies were surveyed with respect to their use or potential use of AVL. Findings from the survey showed that only eight states had deployed AVL, in addition to several municipalities and one Canadian province. None of the surveyed agencies had conducted quantitative assessments of the benefits of system deployment. Qualitative and perceived benefits taken from the aggregated survey data were used to develop estimates of benefits likely to be realized from an AVL deployment. Savings from improved fleet management, paperwork reduction, and reductions in snow-related crashes were compared with the system investment and maintenance costs. Costs for statewide deployment were estimated to be about $9 million, with about $800,000 needed annually for maintenance. Benefit-cost ratios were calculated for three deployment schedules based on conservative and moderate assumptions. The analysis estimated benefit-cost ratios would be at least 2.6 and probably closer to 25. The annual efficiency savings for the Kansas Department of Transportation are estimated to be nearly twice the annual maintenance cost of the system. These results suggest that AVL offers substantial potential in improving the efficiency and effectiveness of highway maintenance operations.

Proceedings ArticleDOI
09 Jun 2003
TL;DR: A new approach to the taxi assignment problem in a mobile environment based on optimization and simulation is presented to predict the impact of the interaction between the assignment algorithm and fleet management in the mobile environment on the desired quality of service for the mobile users.
Abstract: The convergence of multiple technologies, including the Internet, wireless communications, geographic information system, location technologies, and mobile devices, has given rise to new types of information utilities that may be referred as mobile location-based services (LBS). LBS can be described as applications that exploit knowledge about where an information device (user) is located. For example, location information can be used to provide automobile drivers with optimal routes to a geographic destination. Specifically, we examine a context where the people need to move physically from one location to another via taxis. In this scenarios the user is in control of the location information associated with the mobile device. However, problems arise when a fleet management application use that dynamic information to provide the best taxi assignment. This paper presents a new approach to the taxi assignment problem in a mobile environment based on optimization and simulation. Our specific interest is to predict the impact of the interaction between the assignment algorithm and fleet management in the mobile environment on the desired quality of service for the mobile users. The paper also discusses the current approach and limitations of the new approach and some simulation results, such as average transport time and unserved mobile users average. Finally, we present some conclusions.

01 Jan 2003
TL;DR: In this paper, the authors focused on two scheduling components: timetables and vehicle scheduling, and discussed the determination of vehicle frequencies and the construction of alternative public timetables for both cases of even headway and even average load.
Abstract: The following four basic components, performed usually in sequence, are included in public transit operational planning process: network route design; setting timetables; scheduling vehicles to trips, and assignment of drivers/operators. This chapter concentrates on two scheduling components: timetables and vehicle scheduling. The first part of the chapter discusses the determination of vehicle frequencies and the construction of alternative public timetables for both cases of even headway and even average load. Then provided is an overview on exact solutions to the vehicle scheduling problem and a description of a graphical heiristic procedure for the determination of minimum fleet size and its lower bound.

Journal ArticleDOI
TL;DR: The vision of how motor vehicle information and communications technology can be exploited for transportation engineering is described and the social, technical, and organizational barriers that need to be overcome to achieve this vision are discussed.
Abstract: Technology already exists to capture and communicate a variety of information from motor vehicles Automobiles are equipped with sensors and can reliably report their location, velocity, and condition via cellular telecommunications Truck location tracking with global positioning systems is common, and prototype systems exist for characterizing surrounding traffic and roadway conditions Given these advancements, we expect that future motor vehicles will be capable of reporting a wide variety of information about their own condition and the local environment, including the condition of the infrastructure on which they travel Many uses exist for the vehicle- and infrastructure-related information that can be transmitted from motor vehicles For example, fleet operators can take advantage of this information for better management of their own fleet, subject to privacy agreements with their own drivers Similarly, this information can be used for traffic control purposes to improve travel times and safety Even though it is becoming technologically feasible to use motor vehicles to transmit a variety of information collected through sensors, social, technical, and organizational barriers exist currently that limit the availability of this information mostly to the private use of the motor vehicle and drivers In this paper, we describe our vision of how motor vehicle information and communications technology can be exploited for transportation engineering We also discuss the social, technical, and organizational barriers that need to be overcome to achieve this vision

Journal ArticleDOI
TL;DR: The taxicab is a good example of early utilitarian deployment of the automobile, a fact often overlooked in automotive historiography focused upon the pleasures of early automobility.
Abstract: The taxicab is a good example of early utilitarian deployment of the automobile, a fact often overlooked in automotive historiography focused upon the pleasures of early automobility. The taxicab is also crucial in understanding how the petrol-driven automobile could become a vehicle for dense urban traffic, an application for which the electric automobile seemed more suited. The dilemma of the choice between electric and petrol engine propulsion played a major role within the management of taxi fleets. Fortunately, the preserved logs of the Amsterdam Atax electric taxicab fleet facilitate a thorough analysis of the factors affecting the choice of propulsion system and show that the electric vehicle could outperform its petrol rival both in technical reliability and in profitability. They also show, however, the weaknesses of the electric propulsion system which meant that the petrol system would ultimately dominate the field.

01 Jul 2003
TL;DR: In this article, the best practices in fleet management for the Minnesota Department of Transportation (MnDOT) were evaluated using a regional study and a national assessment focusing on performance measurements that are most useful in state transportation departments.
Abstract: Benchmarking is used to assess the best practices in fleet management for the Minnesota Department of Transportation (MnDOT). Phase I was a regional study that focused on organizational structure, performance measures and targets, policies, and maintenance in a variety of public and private organizations. Phase II was a national assessment focusing on performance measurements that are most useful in state transportation departments. Thirty-five states participated in the Phase II survey and seven benchmarking interviews were conducted (Arizona, Maine, Michigan, New Hampshire, New York, Oregon, and Pennsylvania) to assess the number, types, and effectiveness of performance measures used in leading state transportation departments. Analysis of data from both phases identified best practices and gaps that MnDOT should consider. Minnesota is assessed to have one of the better fleet management approaches, but many opportunities for improvement are possible. Recommended performance measures are given for the state, district, and shop levels, with appropriate reporting periods (monthly, quarterly, annually). Recommendations are presented regarding control limits, organizational performance indices, strategic planning, predictive maintenance, purchasing standards, cost/benefit analysis, fleet asset centralization, internal rental rates, bar coding, asset replacement, pursuing the Malcolm Baldrige National Quality Award, and review committee makeup. Possible future benchmarking work includes costing, utilization, and asset life cycle analysis.

Journal ArticleDOI
01 May 2003
TL;DR: A new approach to the taxi assignment problem in a mobile environment based on optimization and simulation is presented to predict the impact of the interaction between the assignment algorithm and fleet management in the mobile environment on the desired quality of service for mobile users.
Abstract: The convergence of multiple technologies has given rise to new types of information utilities called mobile location-based services. Specifically, the authors examine a context in which people need to move physically from one location to another via taxis. In this scenario, the user is in control of the location information associated with the mobile device. However, problems arise when a fleet management application uses that dynamic information to provide the best taxi assignment. This particular vehicle-routing problem aims to allocate a taxi fleet to a number of mobile units to minimize the running distance and time. This article presents a new approach to the taxi assignment problem in a mobile environment based on optimization and simulation. Its specific interest is to predict the impact of the interaction between the assignment algorithm and fleet management in the mobile environment on the desired quality of service for mobile users.

01 Feb 2003
TL;DR: In this article, the authors present an asset management strategy that can be used by state DOTs to allocate capital dollars for the dual purpose of purchasing new buses and rebuilding existing buses within the constraints of a fixed budget, when the needs of all constituent agencies in a peer group are considered.
Abstract: The report presents an asset management strategy that can be used by state DOTs to: allocate capital dollars for the dual purpose of purchasing new buses and rebuilding existing buses within the constraints of a fixed budget, when the needs of all constituent agencies in a peer group are considered; and, distribute funds among the agencies in an equitable manner. The proposed procedure includes two optimization models. Model 1 attempts to maximize the weighted fleet life of all the buses that are being purchased and rebuilt for a given peer group. Model 2 is designed to maximize the Remaining Life (RL) of the entire peer group comprising the existing buses as well as those being replaced or rebuilt. Three case studies are presented in the report to demonstrate the application of the models: two with medium sized buses and one with large sized buses. Besides replacement, three other program options are considered: two levels of rehabilitation, and one level of remanufacturing. Necessary budgetary and fleet data were provided by the Michigan Department of Transportation. The case studies show that the proposed method is viable, and can be used for the designated purpose with fleet data currently available with state DOTs. The case studies also identify major shortfalls in funding, and help to underscore the need of increased funding levels to improve the quality of the fleet.


Journal ArticleDOI
TL;DR: The in-car navigation system prototype development and test results under the context of Singapore are introduced, demonstrating GPS positioning of the vehicle in real-time, tracking the vehicle onto a digital map with fix updates every one or two seconds.
Abstract: This paper introduces the in-car navigation system prototype development and test results under the context of Singapore. In the system, integrated GPS/DR is used for continuous vehicle positioning. A digital road network map database is built for the whole Singapore. The database is designed to support map matching, route determination, and route guidance functions. The prototype system demonstrates GPS positioning of the vehicle in real-time, tracking the vehicle onto a digital map with fix updates every one or two seconds. With the map matched vehicle location on the map, voice and/or text guidance is provide to the driver. The vehicle position can also be transferred to control centre through communication data link for the purpose of fleet management.

01 Jul 2003
TL;DR: In this paper, the authors describe a replacement methodology developed to assist equipment replacement at TxDOT that includes life-cycle cost history as one of the replacement criteria, taking full advantage of the comprehensive EOS database.
Abstract: The Texas Department of Transportation (TxDOT) owns and maintains an active fleet inventory of over 17,100 units, replacing about ten percent of the fleet annually. Any methodology that can improve the replacement procedures currently used at TxDOT has the potential of savings millions of dollars. This report describes a replacement methodology developed to assist equipment replacement at TxDOT that includes life-cycle cost history as one of the replacement criteria. This new method takes full advantage of the comprehensive TxDOT's Equipment Operating System (EOS) database. It automatically outputs prioritized replacement lists based on ranking the condition of each unit with respect to the condition of all other units within its class. The research objectives were to develop, test and implement a computerized system capable of updating the analysis data sets, processing and comparing the life cycle cost profiles for all equipment units in TxDOT's inventory, supporting equipment replacement decisions with life cycle cost based replacement criteria, and generating reports in tabular and graphical formats in order to simplify the analysis of the results by TxDOT decision makers. This report, the second of the 4941 series, describes the development of this methodology and the framework of the computer program for its implementation. The third report of this series is the software manual.

Proceedings ArticleDOI
22 Jul 2003
TL;DR: The use of micro-nano NDE sensor technologies for vehicle health monitoring will have profound implications, and will provide a revolutionary way of doing NDE in the near and distant future.
Abstract: Recent advancements in small, microscopic NDE sensor technologies will revolutionize how aircraft maintenance is done, and will significantly improve the reliability and airworthiness of current and future aircraft systems. A variety of micro/nano systems and concepts are being developed that will enable whole new capabilities for detecting and tracking structural integrity damage. For aging aircraft systems, the impact of micro-NDE sensor technologies will be felt immediately, with dramatic reductions in labor for maintenance, and extended useable life of critical components being two of the primary benefits. For the fleet management of future aircraft systems, a comprehensive evaluation and tracking of vehicle health throughout its entire life cycle will be needed. Indeed, micro/nano NDE systems will be instrumental in realizing this futuristic vision. Several major challenges will need to be addressed, however, before micro- and nano-NDE systems can effectively be implemented, and this will require interdisciplinary research approaches, and a systematic engineering integration of the new technologies into real systems. Future research will need to emphasize systems engineering approaches for designing materials and structures with in-situ inspection and prognostic capabilities. Recent advances in 1) embedded / add-on micro-sensors, 2) computer modeling of nondestructive evaluation responses, and 3) wireless communications are important steps toward this goal, and will ultimately provide previously unimagined opportunities for realizing whole new integrated vehicle health monitoring capabilities. The future use of micro/nano NDE technologies as vehicle health monitoring tools will have profound implications, and will provide a revolutionary way of doing NDE in the near and distant future.

01 Jul 2003
TL;DR: The Texas Equipment Replacement Model (TERM) as mentioned in this paper is a computerized system that uses the trendscore to support equipment replacement decisions with life cycle cost based replacement criteria, which is a menu-driven system that can generate data tables and graphs, calculate and compare life-cycle cost profiles and trends, and prioritize units for replacement based on fleetwide comparisons of each unit's condition to the condition of all other units within its class.
Abstract: The Texas Department of Transportation (TxDOT) owns and maintains an active fleet inventory of approximately 17,000 units, replacing about ten percent of them annually. Private and public agencies do not routinely use life-cycle cost as a replacement criteria because, until now, the only way to automate the inspection of thousands of life-cycle cost histories was to define an acceptability threshold for annualized costs. Most fleet managers rightfully consider this practice too inaccurate. The most relevant information provided by a life-cycle cost graph is its trend; units whose life cycle costs have been increasing longer and/or at a faster rate should have higher replacement priority. A major contribution of this research project is the development of the life cycle cost trendscore, a method that enables a computer to mimic replacement decisions made by a person visually inspecting a series of life cycle cost histories. Research project 7-4941 developed and tested the Texas Equipment Replacement Model (TERM), a computerized system that uses the trendscore to support equipment replacement decisions with life cycle cost based replacement criteria. TERM is a menu-driven system that can generate data tables and graphs, calculate and compare life cycle cost profiles and trends, and prioritize units for replacement based on fleet-wide comparisons of each unit's condition to the condition of all other units within its class. This report, the third of the 7-4941 series, consists of the TERM software manual.