Simplifications for single-route transit-ridership forecasting models

The growth in popularity of microcomputers has reemphasized the need for simplified transit-planning techniques. This paper describes and evaluates a single-route ridership forecasting model which is designed to fit within a modest-sized microcomputer. The model is based upon the traditional four-step urban transportation modeling process, but it is simplified by removing the possibility of multiple transfers and by eliminating the highway network. An analysis of model error shows that these simplifications do not appreciably affect the accuracy of the forecasts. A particular advantage of implementing the model on a microcomputer is the user-friendliness that can be achieved by employing interactive color graphics for data input.     

Taxicab operating characteristics in the United States

In 1982, a national survey of U.S. taxicab operators was conducted. This survey sought to assess the economic, operational and organizational status of the industry and to determine how these characteristics have been changing in response to rising costs and an economic recession. Two results of this survey are reported in this paper; the size structure and the organization of the industry. Both of these characteristics show that it has recently been undergoing two fundamental changes. These are the rapid switch away from employees as drivers to independent contractor drivers and decreasing average company size.     

Urban travel demand: The impact of Box-Cox transformations with nonspherical residual errors

We develop an algorithm for solving regression models with Box-Cox transformations on both the dependent and independent variables, while simultaneously taking into account corrections for serial correlation of several orders and for heteroscedasticity. The latter correction is of a general form which contains as special cases most specifications of heteroscedasticity found in practice. We apply the procedure to three urban travel demand functions, two of which are currently used in their linear form by the Montreal Transit Authority, and analyze more than 100 specifications. Our results show that taking into account nonsphericalness of the residuals has a major impact on model parameter estimates, notably on those which determine the functional form of the model, and that, conversely, modifications of the functional form have strong implications for both the structure of autocorrelation and the importance of heteroscedasticity; moreover, we find interactions between autocorrelation and heteroscedasticity structures. We introduce a special measure of elasticity for variables which contain zero observations, particularly dummy variables. Moreover, we find that elasticities of demand and implicit values of time depend to a large extent on the stochastic specification of the model.     

The effects of US shipping regulation on specific aspects of liner conference operation

This paper is the first of two articles by J. E. Davies which seek to explore the incongruities of the USA's current regulatory system. The second paper will cover the overall economic impact of the USA's insistence on open conferences in its trades, whilst the first concentrates on the effects of US regulation on specific aspects of the operation of linear conferences.     

Structural change in the Belgian port system, 1980-1986

Even if market shares of individual ports keep changing every year, structural change in a given port system is generally a slow process. To measure and explain it, tolls such as concentration and specialization indexes, both elementary and generalized, should be used in a temporal prospect.     

Spatial variations in attitudes toward expanded public transit service

Although recent budgetary considerations by the Federal govenment do not portend well for urban public transit, some transit systems are considering expansion into less densely-settled areas further from the Central Business District. Of some concern to planners has been their belief that suburban and rural dwellers may be much less inclined than urban dwellers to support expansion of transit service. This paper presents an analysis of a random-digit dialing/mail-out, mail-back survey conducted in Washtenaw County, Michigan which was designed specifically to examine differences in attitudes between urban and rural residents. Six mutually-exclusive spatial strata were established based upon population density. This paper tests for expected spatial differences in socioeconomic and demographic variables and then examines spatial variations in attitudes toward public transportation. The major conclusion is that the expected spatial variations in attitudes about transit service provision between the spatial strata do not arise. Most of the significant differences found are with respect to questions which relate to where transit is provided. Residents in rural (urban) areas support more strongly the provision of services to rural (urban) areas. Many residents, however, will support transit service that may not benefit them directly.     

Changes in perceived travel cost and time for the work trip during a period of increasing gasoline costs

This study was designed to examine the relationship between actual and perceived values of cost and time for the work trip and to examine how perceptions have changed over a period of dramatically increased travel costs. Variations in the relationship between perceived and actual values were examined as a function of situational and attitudinal variables. Two telephone surveys were conducted one year apart (Fall 1978 and Fall 1979). On the next working day following a survey, a research assistant recreated the respondent's work trip, recorded time values and used distance measures, car type information and parking costs to compute travel cost. The first survey revealed that most auto users were unable to articulate dollars-and-cents driving costs for the work trip, but auto users in the second survey were able to provide fairly accurate cost estimates. Dramatic changes in fuel prices between surveys is probably the main reason for the change in driving cost awareness. Auto users were also asked to rate relative costs of driving a car compared to using the bus for the work trip. These ratings showed that auto users tended to underestimate driving costs relative to bus costs, but this tendency decreased from the first to the second time period. Commuters in all modal groups at both time periods tended to overestimate travel times. Perception of travel time varied as a function of mode, perceived comfort (for car users), and perceived convenience and number of transfers (for bus users).To whom correspondence should be addressed.