Showing papers on "Fleet management published in 1977"

Constructing an Optimal Fleet for a Transportation Schedule

Abstract: A schedule is a set of passages; a passage is a 4-tuple p = p1, p2, p3, p4 where p1, p2 denote departure and arrival terminals, p3, p4 departure and arrival times. A fleet is a partition of the schedule into chains; each chain is a finite or infinite sequence of passages p1, p2,... having the property pn2 = pn+11 and pn4 ≤ pn+13. The fleet-size is the minimal possible dimension i.e., the number of chains of the fleets. The deficit function dt, a for a terminal a is the difference between the number of departures and arrivals occurring at a during the interval [0, t]. It is proved that the fleet-aim is equal to Σamaxt≥0dt, a. A general method for constructing all optimal fleets is described. A special case of periodic schedules is studied and it is proved that a periodic schedule can be decomposed into an optimal periodic fleet. Applications of the deficit function technique to practical scheduling when passages have tolerances for departure times are discussed.

Automatic vehicle location—An overview

Abstract: Automatic vehicle location (AVL) techniques have the potential for improving urban vehicle fleet operations. Various approaches to AVL are discussed and an introductory overview of the current state of the art in AVL technology is presented.

A dead reckoning/map correlation system for automatic vehicle tracking

Abstract: An automatic vehicle locating system using self-contained dead reckoning techniques, corrected by central processor map correlation, has been successfully implemented in a production program. The design studies, development testing, and system implementation of the Fleet Location And Information Reporting System (FLAIRM®) are described.

Queuing Models for Estimating Aircraft Fleet Availability

Abstract: The availability of a small fleet of aircraft in a flying-base, repair-depot combination is modeled and studied. First, a deterministic flow model relates parameters of interest and represents the state-of-the art in the planning of such systems. Second, a cyclic queue model shows the effect of the principal uncertainties in operation and repair and shows the consequent decrease in the availability of aircraft at the flying-base. Several options such as increasing fleet size, investments in additional repair facilities, or building reliability and maintainability into the individual aircraft during its life-cycle are open for increasing the availability. A life-cycle cost criterion brings out some of these features. Numerical results confirm Rose's prediction that there exists a minimal cost combination of end products and repair-depot capability to achieve a prescribed operational availability.

Inventory model of the railroad empty-car distribution process

Abstract: Techniques to improve freight-car fleet use are of considerable interest to the railroad industry. One potentially high improvement area is the disposition of empty cars within the network. This paper reports the first results of inventory control applied to one aspect of the process, namely the sizing of empty-car inventories at points in the network. First we evaluate existing techniques for distributing empty cars on a rail network. These techniques deal primarily with optimizing empty-car movements from areas of surplus to areas of deficit. To account for variations in supply and demand, we designed a discrete event simulation model that can determine optimum inventory level, for a single terminal area, as a function of (a) daily supply variations, (b) daily demand variations, and (c) cost of holding a car in a terminal awaiting loading compared to cost of having no car available to satisfy shipper demand. A first attempt to use the model to evaluate the performance of an actual railroad terminal area indicates that excessive inventories are maintained in surplus terminal areas. The applicability of the model to a real railroad operating situation is also demonstrated.

Method for Estimating Patronage of Demand Responsive Transportation Systems

Abstract: This study has developed a method for estimating patronage of demand responsive transportation (DRT) systems. This procedure requires as inputs a description of the intended service area, current work trip patterns, characteristics of the served population, and the major design choices, such as the vehicle fleet size, changes in fleet size over the day, types of vehicles being used (buses or taxis), and the fare level. Using these data, the model predicts patronage and service levels for each user-specified interval during the day. The modern system has been developed as a software package which includes a set of disaggregate demand models, a set of analytic supply models, and an equilibration procedure. In addition, a simple sketch planning procedure has been developed which can be used for quick, preliminary analysis of DRT sites. /GMRL/

Optimum fleet sizing in the northeast corridor

Abstract: The Regional Railroad Reorganization Act of 1973 mandated the U.S. Department of Transportation to undertake engineering and planning studies for improved passenger rail service in the Northeast Corridor. In order to obtain fleet estimates and to analyze the effects of management strategies a calculation of the optimum number of cars required for a design day service in the Northeast Corridor was undertaken. A linear programing model that determines fleet requirements for several different formulations of the objective function was formulated. Minimum fleet size was then calculated from a demand forecast based on the service standards prescribed in the Railroad Revitalization and Regulatory Reform Act of 1976. Minimum car-kilometers per day and maximum load factor were also found. The analysis indicated that the most heavily traveled portion of the corridor, Philadelphia to New York, might be better served by adding trains between these two cities.

Automotive energy forecasts: impact of price, availability, and efficiency

Abstract: Aggregate automotive fuel demand models are developed for each of New York's 9 SMSA's and the rest of the state, using monthly data from 1972-75. The models estimate annual fuel use from population, VMT, average fleet efficiency, gasoline price and supply, and economic factors such as unemployment, business activity, and labor force participation. Gasoline price elasticities determined from the models are found to decrease with city size, to about -0.10; supply elasticities vary between 0.08 and 0.80. Forecasts of NYS automotive fuel use are then made for each year from 1975-1990, testing 3 scenarios: (A) fleet efficiency rising to 27.5 mpg, coupled with trend (2% annual) growth in per-capita mobility and stable real prices ($1.16 gal. in 1990); (B) fleet efficiency rising to only 22 mpg, but prices increasing to meet the demand drop in Test A; (C) fleet efficiency rising to only 22 mpg, coupled with trend growth in per-capita mobility and stable real prices. Results show that full fleet turnover (Test A) permits continued growth in per-capita mobility and stable real prices, while achieving a 24% savings in gasoline demand. With partial fleet turnover (Tests B and C), however, this same conservation can only be achieved by much lower (0.5% annual) per-capita mobility growth coupled with significantly higher prices ($2.08/gal. in 1990). If the conservation goal is dropped, partial turnover can sustain continued mobility growth and stable real prices at 1975 demand levels. It is concluded that full fleet turnover is essential for achieving significant gasoline conservation in N.Y. with reasonable gasoline prices and continued mobility growth. A number of actions are therefore suggested to encourage the purchasing of fuel-efficient vehicles. /Author/

Bus Acquisition and Retirement Decisions

Abstract: Bus fleet planning is part and parcel of orderly management of a bus transit property. Budgetary provisions need to be made for the future acquisitions of new buses; maintenance programs tailored to the upcoming retirement of old ones; subsidies requested, orders placed etc. It is not uncommon to prepare Strategic Acquisition and Retirement Programs several years into the future for internal planning or as a part of request for subsidies towards the purchase of new equipment, or for both.

A transit planning methodology for small cities

Abstract: This article, which describes a conceptual systems approach framework, describes the type and range of transit most effective in a small city and outlines a regression model which can be a starting point for ridership estimation. The transit system must possess flexibility and capability of expansion to accomodate the additional ridership which will be generated after a period of operation. Travel forecasts and continuous monitoring of the operation are essential. A route selection process is discussed and comments are made on scheduling. The fare structure and fare plans are considered and it is noted that they should be: demand oriented, logical and based on rational criteria, easy to remember, simple and preferably with a unistructure, and with minimum or preferably no transfer charge. Factors affecting the fleet size determination are discussed. Practical aspects of transit planning methodology are reviewed, and the use of a successive overlay technique for examining proposed route configuration is outlined. Selection of the final transit system is based on the evaluation of various elements such as fleet size, vehicle mix, scheduling, fare structure, and fare plans as well as economic analysis. Community goals are also important to the evaluation process.

The potential for helicopter passenger service in major urban areas

Abstract: An interurban helicopter cost model having the capability of selecting an efficient helicopter network for a given city in terms of service and total operating costs was developed. This model which is based upon the relationship between total and direct operating costs and the number of block hours of helicopter operation is compiled in terms of a computer program which simulates the operation of an intracity helicopter fleet over a given network. When applied to specific urban areas, the model produces results in terms of a break-even air passenger market penetration rate, which is the percent of the air travelers in each of those areas that must patronize the helicopter network to make it break even commercially. A total of twenty major metropolitan areas are analyzed and are ranked initially according to cost per seat mile and then according to break-even penetration rate.

Sources of alcohol fuels for vehicle fleet tests

Abstract: Twenty-five coal gasification projects were reviewed for the purpose of determining if they offered an opportunity to provide a source of methanol for a fleet vehicle test program. All were concerned with the gasification of coal to produce a low, medium, or high Btu gas or a liquid fuel. The analysis revealed that only four programs offered a reasonable opportunity for completion of a commercial scale gasification plant and full operation in the foreseeable future. Further, all four elected to use the Lurgi gasification technology together with the Lurgi Rectisol gas cleanup process incorporating methanol as the absorbing medium. Consequently all four projects are candidates for supplying the 150 tons needed for a fleet vehicle test program. The American Natural Gas--People Gas Companies program at Beulah, North Dakota, is particularly of interest as a source since they have already made the decision to produce their own methanol requirements on-site. All four projects are currently halted owing to the need for resolving the capital financing of the projects. If federal loan guarantees are forthcoming in amounts realistically tailored to today's construction costs, all four projects could proceed promptly and 1982-83 operational date would be a reality. (ERA citation 03:024621)

Habit check of seeing and responding in driving

Abstract: By learning to spot the clues, an observer riding with a driver can identify habits of seeing and responding. Many business and industrial firms that operate large fleets of motor vehicles have put into use a system for checking in traffic the seeing and responding habits of their drivers and for explaining to them the steps they should practice to upgrade any habits that need improvement. This article explains a revised version of the habit check program which was developed 2 decades ago. Conclusions reached from follow-up contacts with fleet supervisors using the system are discussed. The seeing-responding process which is made up of 5 steps is reviewed. Notes are provided on conducting the habit check, and clues are provided to the driver's seeing and responding habits. The follow-up procedure after the habit check is also discussed.

The influence of the merchant marine act of 1936 on. defense shipping capability—the last 25 years

Abstract: This paper first provides a brief overview of the history of the American Merchant Marine as an introduction to the Merchant Marine Act of 1936. Those sections of the Act which have been deemed to be major factors in the availability of shipping capability are discussed in summary form to provide the reader with a basic understanding of construction and operating differential subsidies, mortgage guarantees, and tax exempt capital construction funds. The implementation of these provisions is then discussed, beginning with the MARINER Building Program and followed by the Cargo Ship Replacement Program and the Bulk Carrier Construction Program. The recent history of the Act is then traced to present an indication of the numerical impact of certain programs. The present status of the U.S. Merchant Fleet, with respect to its share of U.S. foreign trade, is finally discussed as one indicator of the level of defense shipping capacity now available.