An aggregate demand model for intercity passenger travel in Sri Lanka

Inspite of the inherent weaknesses in aggregate demand models, they continue to be used in everyday applications, especially in developing countries. The largely data intensive disaggregate model preclude its application in many cases. This paper attempts the formulation and calibration of an aggregate total demand model for estimating inter-district passenger travel by public transport in Sri Lanka. In its process, an investigation is made of the common problems in the aggregate approach while examining possible remedial measures to improve the accuracy and (hence) the usability of the aggregate model. It is argued that commonly used variables and functional forms are inappropriate for making accurate estimates in developing countries. Consequently, the model calibration is shown to incorporate variables representing urbanisation, under-development, transfers, a mode-abstract cost function and intrinsic features. The necessity for functional form for each variable to be based on behavioral assumptions that are tested using the Box-Cox transformation for ensuring the best fit of the data is also observed. Although, the model form was calibrated for Sri Lanka, the model is generalised in order for its applications to other countries as well as, both, inter-district and intercity travel demand estimation.     

The potential for British coastal shipping in a multimodal chain

A strategy to revitalize coastal shipping within Great Britain is investigated. An examination of the regulatory environment shows government, at both the EU and British levels, aware of the environmental benefits of coastal shipping compared to road freight transport, if only mildly supportive in tangible terms. The geography of Great Britain and the modern preference for just-in-time deliveries have severely restricted the ability of coastal shipping to compete effectively with road freight transport. The primary objective of the paper is to investigate whether coastal shipping could be integrated into a multimodal door-to-door supply chain, where it is currently hampered by high costs of transhipment, slow transport speeds, and the incongruity of load sizes between land and sea modes. Integration requires the co-operation of all organizations within the multi-modal supply chain. However, coastal shipping companies have been known to be individualistic and mistrusting of alliances. Therefore, a Delphi study is undertaken to investigate the standpoint of leading managers in such companies towards multimodal integration. The results of the Delphi study indicate that managers are in favour of multimodal developments, in particular cooperation between coastal shipping and road haulage. However, there was agreement that the business is highly competitive, and this may prevent the forms of collaboration required for multimodal systems. The secretive nature of the coastal shipping sector could impede joint marketing to promote a mode of transport that is often 'invisible' to shippers. There was little consensus on the relationship that should exist between coastal shipping and ports, a topic worthy of further investigation.     

How much do people value the environment?

The selection and evaluation of road schemes through the Leitch framework is based on a combination of cost-benefit analysis and environmental impact assessment. Both techniques involve the definition and valuation of a number of costs and benefits. These costs and benefits are defined and valued in isolation to each other so that we know virtually nothing about the relative valuation that people assign to different types of costs and benefits which might affect them directly or indirectly. This paper outlines the development of a method which allows people to conceptualise the costs and benefits of a road scheme in their own terms and then to rank schemes in relation to those costs and benefits. This method is based upon an interview process involving the use of repertory grid technique. The information from the repertory grid technique is used as a sound basis for determining trade-offs between attributes and for attempting to obtain monetary valuations of different project attributes. A number of exploratory interviews are reported which outline some of the difficulties with a number of the survey features including the choice of case-study, interviewer and information biases and sample and non-response biases. Various ways of dealing with these difficulties are discussed.     

Aspects of family and kinship in a North Carolina coastal community: a comparative study

The almost total absence of social-science data on North Carolina coastal fishing communities has provoked this preliminary study of the role played by family and kinship ties among fishermen and boat builders in such a community, with a view to developing new fisheries management strategies from an assessment of the social and economic impacts of those which already exist.     

Risk analysis of jackup rigs

Increasing attention has been focussed in the North Sea and elsewhere on the quantification of the risks of working in a hazardous enviroment: the offshore world. The perception of risk with respect to mobile rigs has often been vague and uninformed. This paper attempts to put the risks with respect to jackup rigs into perspective by quantifying them and comparing them to other risks.

This paper contains a few risk comparisons with fixed platforms, semi-submersibles, and drillships. Historical casualties are used in an example to show how a change intended to make an operation safer, may result in the opposite effect.

Examining risks from losses due to environmental overload, the conclusion is reached that jackups are very safe structures: there appears to be no jackup, in the timeframe examined, that has been lost because of a deficiency in the calculation methods currently in use by knowledgeable experts.     

Simulation and Visualisation of the Dynamic Behaviour of an Overhead Power System with Contact Breaking

For high speed rail traffic it is necessary to design overhead power systems which minimize the contact loss between pantograph head and contact wire. To predict how different design solutions will behave it is favourable to model and simulate the dynamic behaviour. In this paper a model of an overhead power system is specified and used in simulation. The model is suitable for simulation with contact loss since it includes specifications of impact conditions between pantograph head and contact wire. Two sets of equations of motion are specified, one for the contact case and one for the non-contact case. The model also includes lateral movement of the wire due to the zigzag span and friction between the pantograph head and the contact wire. It is shown how to make animations of the system behaviour using a MCAE-system. The animations are made using a geometrical model of the system together with results from numerical simulations.

Through the examples provided, use of the mathematical model and the geometrical model is presented. The response is visualised as time histories and phase plane diagrams of different coordinates and as animations of the total system response. The different types of visualisations make an excellent combination when studying the system behaviour of different design solutions.

In one example, simulation using the linearised set of equations gives the same results as simulation using the set of fully nonlinear equations, due to periodic response and the simple alternation of contact conditions. It is shown that the situation when any of the parameters vary suddenly is possible to simulate using the fully nonlinear equations of motion.     

Evaluation of road-rail interaction in Thailand

The main line of the State Railway of Thailand to serve the Northeastern region of the Kingdom was built in 1900 to the town of Korat and subsequently extended to its northern extremity at the Laos border. The Friendship Highway, a modern highway parallel to the railway and serving the same transportation corridor, was completed in 1958 as far as Korat. In 1965 the northern extension of the Friendship Highway was opened to Nong Khai, the northern terminus of the railway.The effect of the nearby and parallel highway on freight traffic - for upland crops, vegetables, rice, kenaf, and forest products - is shown in terms of tonnages dispatched by the railway and in relation to the production of those commodities. Passenger traffic originating on the Northeastern railway line is analysed. Statistics indicating the shift in modal split between road and rail, for both freight and passengers in the Kingdom, are presented for a six-year period. An estimate of the loss in revenue for the Korat-Nong Khai segment of the railway has been made for both originating passengers and certain classes of freight traffic. Clearly demonstrated is the unceasing trend toward road haulage of freight and the use of highway buses by intercity passengers. This paper is intended to draw attention to the magnitude of the problem rather than to suggest definitive solutions.