Showing papers on "Fleet management published in 2004"

Ship Routing and Scheduling: Status and Perspectives

Abstract: The objective of this paper is to review the current status of ship routing and scheduling. We focus on literature published during the last decade. Because routing and scheduling problems are closely related to many other fleet planning problems, we have divided this review into several parts. We start at the strategic fleet planning level and discuss the design of fleets and sea transport systems. We continue with the tactical and operational fleet planning level and consider problems that comprise various ship routing and scheduling aspects. Here, we separately discuss the different modes of operations: industrial, tramp, and liner shipping. Finally, we take a glimpse at naval applications and other related problems that do not naturally fall into these categories. The paper also presents some perspectives regarding future developments and use of optimization-based decision-support systems for ship routing and scheduling. Several of the trends indicate both accelerating needs for and benefits from such systems and, hopefully, this paper will stimulate further research in this area.

Real-Time Multivehicle Truckload Pickup and Delivery Problems

Abstract: In this paper we formally introduce a generic real-time multivehicle truckload pickup and delivery problem. The problem includes the consideration of various costs associated with trucks' empty travel distances, jobs' delayed completion times, and job rejections. Although very simple, the problem captures most features of the operational problem of a real-world trucking fleet that dynamically moves truckloads between different sites according to customer requests that arrive continuously.We propose a mixed-integer programming formulation for the offline version of the problem. We then consider and compare five rolling horizon strategies for the real-time version. Two of the policies are based on a repeated reoptimization of various instances of the offline problem, while the others use simpler local (heuristic) rules. One of the reoptimization strategies is new, while the other strategies have recently been tested for similar real-time fleet management problems.The comparison of the policies is done under a general simulation framework. The analysis is systematic and considers varying traffic intensities, varying degrees of advance information, and varying degrees of flexibility for job-rejection decisions. The new reoptimization policy is shown to systematically outperform the others under all these conditions.

Airline Schedule Planning: Integrated Models and Algorithms for Schedule Design and Fleet Assignment

Abstract: Constructing a profitable schedule is of utmost importance to an airline because its profitability is critically influenced by its flight offerings. We focus our attention on the steps of the airline schedule planning process involving schedule design and fleet assignment. Airline schedule design involves determining when and where to offer flights such that profits are maximized, and fleet assignment involves assigning aircraft types to flight legs to maximize revenue and minimize operating cost. We present integrated models and solution algorithms that simultaneously optimize the selection of flight legs for and the assignment of aircraft types to the selected flight legs. Preliminary results, based on data from a major U.S. airline, suggest that significant benefits can be achieved.

CO2 efficiency in road freight transportation: Status quo, measures and potential

Abstract: Road freight transport continues to grow in Germany and generates 6% of the country’s CO2 emissions. In logistics, many decisions influence the energy efficiency of trucks, but causalities are not well understood. Little work has been done on quantifying the potential for further CO2 reduction and the effect of specific activities, such as introducing computer assisted scheduling systems to trucking firms. A survey was survey out and linked fuel consumption to transport performance parameters in 50 German haulage companies during 2003. Emission efficiency ranged from 0.8 tonne-km to 26 tonne-km for 1 kg CO2 emissions. The results show potential for improvements given a low level of vehicle usage and load factor levels, scarce use of lightweight vehicle design, poorly selected vehicles and a high proportion of empty runs. IT-based scheduling systems with telematic application for data communication, positioning and navigation show positive effects on efficiency. Fuel use and transport performance was measured before and after the introduction of these systems.

A Robust Fleet-Assignment Model with Hub Isolation and Short Cycles

Abstract: Airline decision makers cancel flights in operations because of disruptions. When canceling a flight, they usually cancel a cycle, a sequence of flights that begins and ends at the same airport. Consequently, a fleet assignment and aircraft rotation with many short cycles is frequently less sensitive to a flight cancellation than one with only a few short cycles. In this paper, we determine a lower bound for the number of short cycles using the hub connectivity of a fleet assignment, and we present fleet-assignment models (FAMs) that embed many short cycles and reduce hub connectivity within a solution. We show that solutions to such models perform better in operations than those of traditional FAMs that minimize planned operating cost and passenger spill.

Multi-mode in-vehicle control unit with network selectivity for transmitting vehicle data for fleet management

Abstract: A multi-mode in-vehicle control unit (ICU) contains a plurality of modems. Each modem allows the multi-mode ICU to transmit vehicle data over a different kind of transmission network. Exemplary transmission networks include wireless data networks, cellular telephone networks and satellite networks. Vehicle data is collected. The multi-mode ICU selects one of the modems for transmission of vehicle data to a processing center. Priorities can be assigned to the transmission networks and or modems to control order the transmission network selection process.

Anticipatory Route Selection

Abstract: Mobile communication technologies enable communication between dispatchers and drivers and hence can enable fleet management based on real-time information. We assume that such communication capability exists for a single pickup and delivery vehicle and that we know the likelihood, as a function of time, that each of the vehicle's potential customers will make a pickup request. We then model and analyze the problem of constructing a minimum expected total cost route from an origin to a destination that anticipates and then responds to service requests, if they occur, while the vehicle is en route. We model this problem as a Markov decision process and present several structured results associated with the optimal expected cost-to-go function and an optimal policy for route construction. We illustrate the behavior of an optimal policy with several numerical examples and demonstrate the superiority of an optimal anticipatory policy, relative to a route design approach that reflects the reactive nature of current routing procedures for less-than-truckload pickup and delivery.

Monitoring traffic and emissions by floating car data

Abstract: Intelligent raffic mangement is widely acknowledged as a means to optimise the utilisation of existing infrastructure capacities. A major requirement intelligent traffic management is the collection of high quality data on traffic conditions in order to generate accurate real-time traffic information. The approach to be described here generates this information by a fleet of taxis equipped with GPS which act as Floating-Car-Data (FCD) provider for a number of metropolitan areas. The first part of this paper describes the methodology of setting up this data base. The information collected enables various applications such as real-time traffic monitoring, time-dynamic routing and fleet management. The second part of the paper proposes a framwork for using these data additionally to include environmental effects into intelligent traffic managemnt systems. To this end, a mapping between travel times and traffic flows is proposed. Some challenges related to the computation of emissions from velocity profiles are discussed. Equipped thes ingredients, an environmental friendly intelligent traffic management might be in reach.

Ferry service network design: optimal fleet size, routing and scheduling

Abstract: The study formulated a ferry network design problem by considering the optimal fleet size, routing, and scheduling for both direct and multi-stop services. The objective function combines both the operator and passengers’ performance measures. Mathematically, the model is formulated as a mixed integer multiple origin–destination network flow problem with ferry capacity constraints. To solve this problem of practical size, this study developed a heuristic algorithm that exploits the polynomial-time performance of shortest path algorithms. Two scenarios of ferry services in Hong Kong were solved to demonstrate the performance of the heuristic algorithm. The results showed that the heuristic produced solutions that were within 1.3% from the CPLEX optimal solutions. The computational time is within tens of seconds even for problem size that is beyond the capability of CPLEX.

Fleet Assignment Using Collective Intelligence

Abstract: Product distribution theory is a new collective intelligence-based framework for analyzing and controlling distributed systems. Its usefulness in distributed stochastic optimization is illustrated here through an airline fleet assignment problem. This problem involves the allocation of aircraft to a set of flights legs in order to meet passenger demand, while satisfying a variety of linear and non-linear constraints. Over the course of the day, the routing of each aircraft is determined in order to minimize the number of required flights for a given fleet. The associated flow continuity and aircraft count constraints have led researchers to focus on obtaining quasi-optimal solutions, especially at larger scales. In this paper, the authors propose the application of this new stochastic optimization algorithm to a non-linear objective cold start fleet assignment problem. Results show that the optimizer can successfully solve such highly-constrained problems (130 variables, 184 constraints).

Fleet sizing and vehicle routing for container transportation in a static environment

Abstract: Busan is one of the busiest seaports in the world where millions of containers are handled every year. The space of the container terminal at the port is so limited that several small container yards are scattered in the city. Containers are frequently transported between the container terminal and container yards, which may cause tremendous traffic problems. The competitiveness of the container terminal may seriously be aggravated due to the increase in logistics costs. Thus, there exist growing needs for developing an efficient fleet management tool to resolve this situation. This paper proposes a new fleet management procedure based on a heuristic tabu search algorithm in a container transportation system. The proposed procedure is aimed at simultaneously finding the minimum fleet size required and travel route for each vehicle while satisfying all the transportation requirements within the planning horizon. The transportation system under consideration is static in that all the transportation requirements are predetermined at the beginning of the planning horizon. The proposed procedure consists of two phases: In phase one, an optimization model is constructed to obtain a fleet planning with minimum vehicle travel time and to provide a lower bound on the fleet size. In phase two, a tabu search based procedure is presented to construct a vehicle routing with the least number of vehicles. The performance of the procedure is evaluated and compared with two existing methods through computational experiments.

Fleet size and mix optimization for paratransit services

Abstract: Most paratransit agencies use a mix of different types of vehicles ranging from small sedans to large converted vans as a cost-effective way to meet the diverse travel needs and seating requirements of their clients. Currently, decisions on what types of vehicles and how many vehicles to use are mostly made by service managers on an ad hoc basis without much systematic analysis and optimization. The objective of this research is to address the underlying fleet size and mix problem and to develop a practical procedure that can be used to determine the optimal fleet mix for a given application. A real-life example illustrates the relationship between the performance of a paratransit service system and the size of its service vehicles. A heuristic procedure identifies the optimal fleet mix that maximizes the operating efficiency of a service system. A set of recommendations is offered for future research; the most important is the need to incorporate a life-cycle cost framework into the paratransit service planning process.

Lighted supervisory system for a fuel dispensing nozzle

Abstract: A nozzle is provided for a fleet fuel dispensing system. The nozzle includes an input port that is adapted to receive fuel through a fuel supply hose, and a spout that is configured to dispense fuel into a fuel entry receptacle of a vehicle. A valve assembly is configured to couple the input port with the spout, and is further configured to selectively facilitate the passage of fuel from the input port to the spout. A status light is associated with the nozzle and includes a single LED that is connected with a fleet management system. The status light is configured to selectively illuminate as directed by a fleet management system. The illumination provides information as to whether a vehicle is authorized to receive fuel from the spout. A fuel dispensing system having such a nozzle is also provided.

Traffic preemption system

Abstract: A traffic preemption system is described that includes onboard equipment located on a vehicle and a fleet management center in communication with the onboard equipment. The fleet management center is also in communication with a traffic management center that is in communication with at least one intersection controller, which controls the signals displayed at a traffic intersection. In one embodiment, the invention includes a vehicle equipped with an onboard computer system capable of capturing diagnostic information, estimating the location of the emergency vehicle using information provided by a GPS receiver connected to the onboard computer system and transmitting the captured diagnostic information and estimated location using a wireless transmitter connected to the onboard computer system via a first wireless network. Also included is a fleet management computer system connected to a wireless receiver, where the fleet management computer system and wireless receiver are capable of receiving information transmitted by the on-board equipment, determining whether the received information is from a vehicle requiring intersection preemption and providing the estimated location of vehicles requiring intersection preemption to a traffic management computer system. The traffic management computer system is capable of receiving estimated locations of vehicles requiring intersection preemption from the fleet management computer system and forwarding preemption requests to intersection controllers via a second network.

Value of time for commercial vehicle operators in minnesota

Abstract: The spring load restriction policy of Minnesota has been in effect for over 50 years with no consideration given to the cost that it imposes on the freight industry. A cost-benefit study was recently commissioned to examine the policy's necessity. The cost-benefit analysis required a precise estimate of the value of time for commercial vehicle operators in Minnesota. An estimate was not available from previous studies, or from previous data. The necessary revealed preference (RP) information does not exist, and relevance of previous studies was questioned based on the differences in geographic location and the age of data used to construct the estimates. A sample was constructed from several trucking industry sources to conduct a survey. Interviews were conducted using an adaptive stated preference (ASP) survey to derive an estimate to the nearest dollar. A tobit model was fit to the data from the interviews to derive the estimate for value of time. A mean of $49.42 was found, with a 95% confidence interval from $40.45 to $58.39. Variation in the distribution of values is largely undetermined, with the exception of fleet operation, whether it is a for-hire truck fleet, or a private truck fleet. The current state of the art in using stated preference (SP) methods to evaluate the value of time uses a fee structure in exchange for time savings, in most cases a toll. It has been shown that SP methods typically underestimate the true value of time. The use of a fee structure fails to account for those subjects that avoid paying additional fees for a public good that they may feel they pay for in the form of taxes. The fine structure included in this analysis accounts for these subjects and provides a greater estimate for value of time compared to previous studies.

Resource Constrained Shortest Path Problems in Path Planning for Fleet Management

Abstract: In the management and control of a vehicle fleet on a road network, the problem arises of finding the best route in relation to the mission of the fleet and to the typology of freight or users. Sometimes the route has to be adapted not only to current traffic conditions, but also to the physical, geometric and functional attributes of the roads, related to their urban location and environmental characteristics. This problem is approached here through an extension of the classic Shortest Path problem, named Resource Constrained Shortest Path problem (RCSP), where the resources are related to the road link attributes, assumed as relevant to the specific planning problem. A classification scheme of these attributes is first proposed and RCSP is described and reviewed. Next, a General Resource Constrained Shortest Path problem (GRCSP) is defined, which can be found in all cases where it is necessary to plan, statically or dynamically, the path of a vehicle and to respect a set of constraints expressed in terms of parameters and indices associated with the roads on the network. For this general problem a model has been formulated and a Branch and Cut solution approach is proposed. Computational results obtained on test and real networks during the experimentation of a fleet with low emission vehicles are also given.

Eco-efficiency management program (EEMP)—a model for road fleet operation

Abstract: Fuel consumption has always been a matter of economic concern in road fleet management, giving rise to many initiatives aimed at fostering more efficient energy use. The increasingly awareness of environmental problems now requires these programs to include environmental aspects. A structured Eco-efficiency Management Program (EEMP) is proposed for road fleet operation, taking into account the traditional approach that strives to minimise fuel consumption as well as wider economic and environmental aspects. The EEMP has its potential evaluated in a case study undertaken for INFRAERO, Brazilian’s airport authority, on the operation of its road fleet supporting aircraft ground operations at Rio de Janeiro International Airport. The paper looks at EEMP’s implementation by identifying the program’s phases, its participants and their competencies, eco-efficiency indicators, and performance targets.

The Relative Influence of Fleet Safety Climate on Work-Related Driver Safety

Abstract: In the past, fleet management has primarily had an asset management focus, with safety initiatives being reactive to particular incidents or events. More recently, it has been recommended that fleet managers should work to facilitate a safety conscious organisational culture/climate, though this has not yet been empirically investigated in a fleet setting. This study investigated the influence of fleet safety climate upon three self-reported measures of work-related driver safety: 1) current work-related driver behaviour; 2) past crash involvement while driving for work; and 3) past traffic offences while driving for work. A questionnaire was completed by 323 drivers from three Queensland based fleets. There was a significant positive relationship between fleet safety climate perceptions and the safety of work-related driver behaviour (r = .42). Multiple regression analysis revealed that safety climate perceptions were a significant predictor of current work-related driver behaviour and were a better predictor than other psychological and socio-demographic factors. However, further analyses showed that fleet safety climate did not significantly predict previous work-related crash or offence involvement. Some organisational differences were also explored. These results suggest that while fleet safety climate influences current fleet driver behaviour, the long-term effect of this on crash and offence involvement remains unclear. In practical terms, organisations (particularly fleet managers and supervisors) need to consider the impact of organisational factors upon employee driver behaviour. Further research is required to investigate the association between fleet safety climate and on-road incidents (namely crash involvement and traffic offences).

Retooling the Global Positioning System.

Abstract: The article focuses on the capabilities of the Global Positioning System (GPS) Underlying improved capabilities is a series of system upgrades that include additional satellite signals, increased broadcast power, performance monitoring, guaranteed error bounds, smart antennas that can selectively direct and receive signals, and integration with television and cellular-phone networks GPS got its start when the US Department of Defense launched the first Navstar satellite in 1978 Today some 30 million people regularly track their whereabouts using GPS The receiving units assist in guiding road vehicles, ships and boats, as well as in fleet management for rental cars and buses, and recreational uses The American GPS Navstar satellites are not alone in orbit, however Russian GLONASS navigation satellites share that physical and functional space, and in a few years so will the European Galileo constellation Each time a GPS receiver locates itself on the planet's surface, it trilaterates (a cousin of triangulation) its precise distance from at least four GPS satellites using ranging signals broadcast from overhead In essence, the specially coded radio signals serve as invisible rulers that measure the path from the satellites to the receiver Because mobile users change position rapidly, current GPS receivers also monitor the Doppler shift of the incoming signals--that is, motion-caused shifts of the signal's wavelengths Transmitters onboard GPS satellites broadcast their information through standard radio-frequency (RF) waves Starting in 2005, GPS satellites will begin to broadcast new signals that will boost the robustness of services and help fine-tune their positioning accuracy by eliminating the ionospheric errors INSET: Overcoming GPS Signal Interference

Integrated Approach for Emergency Medical Service Location and Assignment Problem

Abstract: In an emergency medical service (EMS) system, the depot location and fleet assignment greatly affect the average response time, which is the main criterion for measuring system performance. Whereas the EMS depot location problem is a strategic problem, the fleet assignment problem is a tactical one. As such, the EMS depot location and fleet assignment problems are usually solved separately under some simplified assumptions. However, there is a potential for savings in both the average response times and the capital and operating costs if these problems can be solved simultaneously. A simulation model for EMS vehicle dispatching was developed. This model is calibrated with real-world data, and it is incorporated in a genetic algorithm to help solve the EMS depot location and fleet assignment problems simultaneously. Emergency types, their response priorities, and whether or not they require dispatching of multiple units are taken into consideration in the model. The average response time and the capital and operating costs are used as criteria for evaluation.

Industrial vehicle fleet management system

Abstract: Embodiments consistent with the invention are an apparatus for and method of generating data on current utilization of powered industrial vehicles, generating preferred routing assignments for powered industrial drivers, and presenting preferred routing assignments for powered industrial vehicle drivers.

Apparatus and method for controlling moving vehicles

Abstract: Apparatus for controlling vehicles, particularly for security purposes, law enforcement and fleet management, that comprises a car unit (CU) permanently mounted in the vehicles and transmits vehicle identification (ID) and a road unit (RU), consisting of a transmitting beacon and an RU processor, which receives the identification and singles out suspect vehicles. The apparatus may include a portable personal unit (PU), which identifies the driver.

Issues in Real-Time Fleet Management

Abstract: In this editorial comment, new issues in real-time fleet management arising from the advent of Internet-based services and the integration of transportation activities within the supply chain are introduced.

Genetic Algorithm-Based Approach for Optimal Location of Transit Repair Vehicles on a Large Urban Network

Abstract: Determining the optimal location of a fleet of vehicles is necessary in a number of potential applications, such as special repair vehicles for buses on a large public transportation network. The Athens Urban Transport Authority operates a large bus fleet over an extensive network for 19 h a day and serves a population of approximately 4 million people, all in a heavily congested road network. During the 2004 Summer Olympic Games, held in Athens, most spectators, employees, and volunteers were transported to and from Olympic Games venues by public transportation. Dedicated Olympic Games bus lines operated under a tight around-the-clock schedule. During normal operations and particularly during events such as the Olympic Games, incidents such as vehicle breakdowns and minor accidents can have a severe effect on the operation of the public transport network and can cause a significant decrease in the level of service. To help the authority locate bus repair vehicles over the entire network, a decision suppo...

Systems Requirements For a Small Autonomous Tractor

Abstract: This paper proposes some system requirements for a small autonomous tractor that includes some physical attributes as well as behavioural traits in certain conditions or contexts. The tractor should be physically small, lightweight, reliable, have good realtime communication facilities and be managed easily, especially under fleet management. Five internal and thirteen external contexts have been identified that can be used to trigger different behaviours. Four operational modes for the tractor have been identified. Field scouting and mechanical weeding have been identified and described as the first two niche tasks likely to become autonomous.

The replace/repair decision for heavy equipment

Abstract: The fleet of equipment operated by the Virginia Department of Transportation (VDOT) constitutes a large investment, on the order of half a billion dollars. A means of identifying earlier and more accurately those pieces of equipment whose timely replacement would keep the cost of maintaining and operating the fleet to a minimum might entail significant savings for VDOT. The purpose of this study was to evaluate the realism of several cost forecasting equations with a relatively small set of equipment cost data. The approach used in the study was (1) a survey of the practice in other states and other agencies and (2) regression analysis of a set of available maintenance and repair cost data from VDOT's Equipment Management System. The authors found that a logarithmic model of variable cost as a function of fuel expense provides a plausible fit to the cost data but that a great deal of the variation in the data remained unexplained. The authors recommend that when identifying candidates for replacement from among the hundreds of (superficially identical) machines within a given equipment type, VDOT's central office and district equipment management compute one additional statistic: the ratio between the average labor and parts cost per dollar of fuel (or per mile) year to date and the average labor and parts cost per dollar of fuel (or per mile} life to date. This statistic would permit an estimate of the expected unit cost for the following year. The authors further recommend that more equipment cost data be archived at the end of each fiscal year.

Developing a fleet standardization index for airline pricing

Abstract: Quantifying subjective aspects in a difficult task that requires a great dedication of time from researchers and analysts. Nevertheless, one of the main objectives of it is to pave the way for a better understanding of the focused aspects. Fleet standardization is one of the subjective aspects that is extremely difficult to turn into numbers. It is of great importance to understand the benefits that may come from a higher level of standardization for airlines. A more standardized fleet may represent lower costs of operations and maintenance plus a much better planning of routes and flights.

Intelligent Vehicle Routing and Scheduling

Abstract: Distribution systems are dynamic providing many challenges for traditional optimization methods. Vehicle routing and scheduling procedures need to be able to cope with uncertainty in order to provide effective decision support systems for fleet managers. This paper presents a new method of representing uncertainty of travel times between customers based on spare time, that is the amount of time that vehicle arrives at a customer before the end o the time windows. Spare time is incorporated within the optimization procedures as an indirect benefit. An example was used to estimate the benefits of using the spare-time model compared with the tradition model. Travel speeds were simulated representing a wide range of traffic conditions. Both models had similar performance of both models with good travel time conditions. However, the Spare-Time model had substantially less delay costs incurred in congested traffic conditions. The Spare-Time model was shown to be more robust with respect to travel time conditions than the conventional model. Significant overall savings in direct costs were predicted. Increased levels of service for customer were also achieved.

Asset Management Strategy to Meet Long-Term Transit Fleet Needs of State Departments of Transportation

Abstract: State departments of transportation (DOTs) 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 bus replacement. An asset management strategy is presented for state DOTs to meet their long-term fleet needs. It is a two-stage process: (a) allocating capital dollars for the dual purpose of purchasing new buses and rebuilding existing buses (taking into consideration the needs of all the constituent transit agencies) and (b) distributing funds among the agencies in an equitable manner. The proposed management strategy 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, within the constraints of a fixed budget. Model 2 is designed to maximize the remaining life of the entire peer group composed of the existing buses as well as those being replaced or rebuilt. The need for every single bus that is eligible for replacement is addressed in the model through either replacement or rebuilding. A comprehensive case study depicting a 7-year planning cycle for the entire fleet of medium-sized buses in the state of Michigan is used to demonstrate the strategy. A plan for evaluating the strategy is also presented and demonstrated. Results show that the strategy is viable and that it can be used for the designated purpose with fleet data that are currently available to the transit agencies. Even though the strategy is demonstrated with medium-sized buses, it will function efficiently with buses of different sizes and with a different number of agencies.