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.     

An investigation of passenger interchange and train standing time at LRT stations: (ii) Estimation of standing time

The standing-time of trains at urban rail stations is pertinent to determining the line capacity and fleet size. The assumption of uniform boarding and alighting leads to under-estimation of the standing time. It is shown that the train standing-time is related to the fraction of boarders and the maximum demand for boarding and alighting at a door. It is further shown that the probability distribution of passengers at a door depends on the platform entrance locations. A methodology that takes into account the above factors is proposed for estimating the train standing-time.     

The compressive behavior of advanced double hull structure—A review of current research at David Taylor

It has long been recognized that the compressive behavior of primary ship structural components plays a vital role in the design of surface ship hulls. This is equally as true for the new advanced double hull concept as it is for the more conventional surface ship configurations. What is different, however, is the nature of the structural mechanics phenomena which must be addressed due to the double hull's more radical departure from conventional design and construction practices. With increasing interest and attention being shown in this new concept, the David Taylor Model Basin has over the past few years initiated a number of research efforts which have and are continuing to address various aspects of the behavior of double hulls and their components to primary compressive loadings. These studies have as their ultimate goal the development of practical, user oriented design methods for double hull structure and as such currently focus on more approximate, rather than mathematically rigorous, approaches to the various structural phenomena being considered. This paper is in essence a progress report on a selected number of these efforts and describes the results achieved to date as well as the ongoing efforts and those planned for the future. This report focuses primarily on three recent studies: (1) a preliminary look at the relative significance of local versus general instability failure of double hull structure; (2) small scale experimental analysis of double hull sections using rigid vinyl modelling; and (3) the application of beam-on-elastic-foundation analysis methods for high aspect stiffened plates as it relates to double hull structure. In addition to these major topics, the report also includes a brief discussion of other ongoing and planned efforts relevant to the advanced double hull.     

A spatial equilibrium port cargo projection model

A mathematical spatial programming model developed to analyse changes in international and hinterland commodity flows through a regional port system is applied to wheat shipments through the U.S. Pacific Northwest port system. Two scenarios, one focusing on a Chinese quarantine on wheat shipments from the Pacific Northwest and the other on possible closure of barge transportation on the Columbia-Snake River, illustrate the capacity of the model to evaluate the impacts of international and hinterland shocks on the regional port system.     

The port-routeing behaviour of short-sea ship operators; theory and practice

This paper provides an interpretation of a port-routeing pattern of short-sea shipping services which has emerged in recent years. After basic definition. a macro theory of port routeing is presented together with an examination of the business environment of operation. Greater refinement is subsequently added with reference to the behavioural characteristics displayed by a number of individual ship operating companies in port routeing as revealed by a series of in-depth interviews. Specific illustration is provided by the Great Britian-Frances market and the paper concludes by suggesting some factors to influence the development of the future port-routeing pattern.     

A note on using Davidson's function in equilibrium assignment

This paper describes the use of the Davidson congestion function in modelling network flows using equilibrium assignment. A modification to the function is given, which defines the function over all flows values, and consequently removes computational difficulties noted in earlier studies. The modification requires the inclusion of an additional model parameter, and the selection of a suitable value for this parameter is studied for two sets of data. The modified Davidson function is also compared to two alternative functions; a step-wise linear function and a quartic polynomial function, which have both been proposed as congestion functions. Comparisons are made between observed link volumes and the assigned volumes from these models. It is concluded that the modified Davidson function is useful for inclusion in an equilibrium assignment model, given its ability to reflect differences in network link type (e.g. capacity and speed) and environment through its parameters, the conceptual advantage of the function through its derivation from queueing theory, and the previous discovery of reliable methods for estimating its parameters. A value of about 0.8–0.9 is suggested for the parameter (μ, 0 < μ < 1) introduced in the modification.     

Wheel/Rail Contact: Geometrical Study*

Before trying to ascertain the precise nature of the Wheel-Rail contact (internal stresses and strains, wear and friction, security against a derailment, dynamic behaviour of the vehicle, etc.) the geometrical problem must necessarily be solved. That is, for each position of the wheelset (this is defined by 6 parameters, of which only 4 are independent) the two dependent parameters and the coordinates of the points of contact of each wheel, and rail must be obtained. A new method is proposed of obtaining the spatial position of a wheelset with reference to the rails, from the most general point of view.     

Rail freight transportation: A review of recent optimization models for train routing and empty car distribution

This paper describes two types of rail transportation problems in detail. These are train routing and makeup, and empty car distribution problems. Some of the recent optimization models which address these problems are reviewed and the areas for potential improvements in rail transportation literature are identified. The type of interactions which exist between routing, makeup, and empty car distribution decisions are highlighted and potential areas for future research are identified.     

Canada and the Liner Code of Conduct: Consumerism and public policy

This paper focuses on the potential effects the UNCTAD Liner Code of Conduct's provisions for cargo reservation on consumers of shipping services, with special reference to Canada. It is clear that as more nations enact flag-discriminating legislation then fewer choices amongest distribution options will exist for the consumer. This will involve nations like Canada in a fundamental reassessment of their current shipping policy, since the rationale of 'free market' competition will no longer be valid: carrier and services options will be curtailed. In the light of this, Canada will be forced to examine the concepts of 'free trade' and 'private sector enterptise' and develope a considered response that protects the consumer interest.