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41.
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. 相似文献
42.
Robert H. Robimson 《Maritime Policy and Management》1976,4(1):21-31
The United States Congress reasserted the desire for continued financial support to domestic merchant-ship construction when in 1970 it amended the Merchant Marine Act of 1936 [1]. With regard to the shipbuilding industry, the most significant changes contained in the Merchant Marine Act of 1970 [2] are those designed to reduce the construction differential subsidy and to increase the variety of vessels that might be subsidized. Sections 501(a), 502(a), and 502(b) of the 1936 Act were amended to facilitate the reduction in subsidies; Section 905(a) was modified to encourage the subsidized construction of liquid and dry bulk cargo vessels. After a cursory review of the 1970 amendments to the 1936 Act, this paper is directed to ascertaining the results, in general, of the changes and whether they have generated increased domestic shipyard productivity and lower subsidy rates. 相似文献
43.
Transportation - Although much has been written about the economics of transit tax financing, public views and opinions toward alternative tax sources have received comparatively short shrift. This... 相似文献
44.
Robert J. McCalla 《Maritime Policy and Management》1982,9(4):279-293
The administration, management and development of ports in Canada is a Federal government responsibility. This centralist control of ports has been the subject of criticism by many for a variety of reasons, not the least of which is that it is not responsive enough to the affairs of the local level. This problem, along with others, has resulted in the introduction in the Canadian Parliament of proposed legislation over the past five years to alter port administration and development in Canada. The proposals culminated in the recent passage of the Canada Ports Corporation Act which, among other things, will see the abolition of the National Harbours Board. A review of the administrative structure the new Act replaces, along with a review and assessment of the Act itself and the proposed legislation which predated it, forms the basis of this paper. It will be seen that because of the new Act the centralist approach to port administration is maintained, but greater local autonomy and financial self-sufficiency will also be available to ports. However, the central administration will still have the problem of co-ordinating the development of Canadian ports, since ports will continue to be constituted under at least four different pieces of legislation. 相似文献
45.
A path-based user-equilibrium traffic assignment algorithm that obviates path storage and enumeration 总被引:2,自引:0,他引:2
This paper presents a novel user-equilibrium (UE) traffic assignment algorithm, which under conventional assumptions, promises to compute UE arc flows to acceptable precision, regardless of the network’s topology, size or congestion:
- • The algorithm takes the simple approach of shifting flow from a costliest path to a cheapest path until the costs of all used paths are within a given of the cheapest.
- • Because of being path-based, it avoids tailing.
- • In spite of being path-based, it neither stores nor enumerates paths.
- • These efficiencies derive from decomposing the problem into a sequence of easy single-origin problems on acyclic sub-networks.
46.
Robert G.V. Baker 《Transportation Research Part B: Methodological》1983,17(1):55-66
The hydrodynamic model of traffic flow is presented and interpreted. Traffic dimensions are defined for the dynamic entities of flow and the behaviour of congestive and dispersive flow is discussed dependent on the value of the local traffic transfer number, R. The wave equation is one example of dispersive flow, where quantum numbers define the condition of free flow at the endpoints of the link. The Schrödinger equation is defined and applied to the study of the cyclic work journey and the problem of traffic lights as an harmonic oscillator. 相似文献
47.
Ira Hirschman Claire Mcknight John Pucher Robert E. Paaswell Joseph Berechman 《Transportation》1995,22(2):97-113
In 1992, the authors carried out a statistical analysis of Triborough Bridge and Tunnel Authority (TBTA) crossings in New York City, to determine the impact of toll increases on traffic volumes and revenue. Using twelve years of monthly time-series data, we developed a set of multiple regression models that estimated traffic volumes on each TBTA bridge and tunnel as a function of the toll level and other explanatory variables. In most cases, the estimated toll elasticities were negative and much less than 1.0 in absolute value; the median toll elasticity for automobiles was found to be –0.10. Our finding that automobile travel demand is highly inelastic with respect to toll rates is consistent with most previous travel demand studies. 相似文献
48.
Ulrich Spangenberg Robert Desmond Fröhling Pieter Schalk Els 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2016,54(5):638-652
The influence of wheel and rail profile shape features on the initiation of rolling contact fatigue (RCF) cracks is evaluated based on the results of multi-body vehicle dynamics simulations. The damage index and surface fatigue index are used as two damage parameters to assess the influence of the different features. The damage parameters showed good agreement to one another and to in-field observations. The wheel and rail profile shape features showed a correlation to the predicted RCF damage. The RCF damage proved to be most sensitive to the position of hollow wear and thus bogie tracking. RCF initiation and crack growth can be reduced by eliminating unwanted shape features through maintenance and design and by improving bogie tracking. 相似文献
49.
This paper reports a practical constitutive relation for highway subgrade soils. The proposed model is derived based on the laboratory repeated-load testing of four subgrade soils. Statistical parameters generally used in the power model of subgrade permanent strain are expanded into material constants with engineering significance. The constitutional relation reported in this paper can be used in the mechanistic-based pavement design of highway flexible pavements and railroad tracks. 相似文献
50.
One role often fulfilled by public administrators is to regulate private enterprise in the public interest. The academic literature has not developed this area fully because public administration is not always tasked with this function. Nevertheless, when regulation forms a part of the responsibilities of the public administrator, it is among the most important. An essential foundation for effective regulation is a complete understanding of the implications and impact of regulatory action. In the absence of regulation, entrepreneurial awareness is applied in the private sector exclusively to satisfying consumer wants. In a regulated market, the entrepreneur’s focus is shifted toward regulatory imperatives. Regulation offers non-market opportunities for entrepreneurial innovation, as well as imposing new market constraints. This paper examines regulation of the maritime industry by the US federal government as an example. 相似文献