Uncertainty in the context of highway appraisal

Transport planning is based on traffic forecasts which are subject to great uncertainties. These uncertainties have generally been ignored or, at least, not explicitly included in the planning process. This paper describes the principles behind the estimation of the uncertainty (or range of error) of the forecasts of a traffic model and discusses the means by which this information can be absorbed into the decision-making in transport planning projects. These principles have been applied to the appraisal of a British highway project and throughout the paper reference is made to this project in order to illustrate the results of the practical application of an explicit treatment of uncertainty. It is believed that this approach can and should be developed for application in most areas of transport planning, leading inevitably to an improvement in the quality of the decisions taken.     

The EEZ and the progress of fisheries negotiations January to May 1977

This paper discusses negotiations, relative to sea fisheries, in terms of international arrangements—arrangements between the European Economic Community (EEC) and Third Countries; and those between member states of the EEC.     

The application of cost-benefit analysis to transport investment projects in Britain

This paper explains the need for the application of cost-benefit analysis to the evaluation of alternative projects for investment in the transport field and outlines briefly the historical development of the technique. The results of a comparative survey of a number of cost-benefit studies which have been carried out in Britain and some conclusions as to their thoroughness and comprehensiveness (or otherwise) are presented. The article concludes with a number of specific and detailed recommendations to remedy apparent methodological weaknesses. Six of these recommendations seem to merit particular attention:

1. The viewpoint of most studies should be extended so as to avoid confinement, for example, within an arbitrary local government boundary, and a wider range of “externalities” should be considered. Intangibles should be included explicitly in all such evaluation exercises.
2. The actual incidence of costs and benefits should be examined in order to indicate the directional impact of the project and its implications in terms of equity. The elimination of transfer payments and double-counting should be postponed until the latest possible stage in the evaluation.
3. Equity considerations should be investigated in any transportation plan, since most projects have considerable equity implications for particular areas or socio-economic groups.
4. Discounted cash flow techniques, which are still used only in a minority of transportation studies, should become standard practice. Most evaluations are based on a single-year rate of return, or at best on simple trend forecasting. More resources should be devoted to proper evaluation of alternative plans which give due importance to the cost and benefit streams through time.
5. Sensitivity analysis should be used in all transportation evaluations. Knowledge of the impact of different assignments, shadow prices, and discount rates are essential information for any decisionmaker.
6. Last, but not least, much greater communication should exist between analyst and decisionmaker than has existed in the past.

     

A method to assess demand growth vulnerability of travel times on road network links

Many national governments around the world have turned their recent focus to monitoring the actual reliability of their road networks. In parallel there have been major research efforts aimed at developing modelling approaches for predicting the potential vulnerability of such networks, and in forecasting the future impact of any mitigating actions. In practice—whether monitoring the past or planning for the future—a confounding factor may arise, namely the potential for systematic growth in demand over a period of years. As this growth occurs the networks will operate in a regime closer to capacity, in which they are more sensitive to any variation in flow or capacity. Such growth will be partially an explanation for trends observed in historic data, and it will have an impact in forecasting too, where we can interpret this as implying that the networks are vulnerable to demand growth. This fact is not reflected in current vulnerability methods which focus almost exclusively on vulnerability to loss in capacity. In the paper, a simple, moment-based method is developed to separate out this effect of demand growth on the distribution of travel times on a network link, the aim being to develop a simple, tractable, analytic method for medium-term planning applications. Thus the impact of demand growth on the mean, variance and skewness in travel times may be isolated. For given critical changes in these summary measures, we are thus able to identify what (location-specific) level of demand growth would cause these critical values to be exceeded, and this level is referred to as Demand Growth Reliability Vulnerability (DGRV). Computing the DGRV index for each link of a network also allows the planner to identify the most vulnerable locations, in terms of their ability to accommodate growth in demand. Numerical examples are used to illustrate the principles and computation of the DGRV measure.     

Assessing the economic significance of port activity: evidence from ABP Operations in industrial South Wales

The paper seeks to improve the evidence base surrounding regional ports and their economic impact. The paper reveals that industries dependent on the port infrastructure are actually key regional players, often operating in relatively fast growth sectors, and contributing to the economic and social needs of the local economy. The focus in the case element of the paper is the operations of Associated British Ports (ABP) plc in industrial South Wales. In examining the direct and indirect consequences of the port activity the paper adopts an input-output framework of analysis. A better contextualization of the economic impact of ports is shown to be necessary in the devolved policy-making environment in the region.     

Analyzing trade-offs between transportation,inventory and production costs on freight networks

The purpose of this paper is to determine optimal shipping strategies (i.e. routes and shipment sizes) on freight networks by analyzing trade-offs between transportation, inventory, and production set-up costs. Networks involving direct shipping, shipping via a consolidation terminal, and a combination of terminal and direct shipping are considered. This paper makes three main contributions. First, an understanding is provided of the interface between transportation and production set-up costs, and of how these costs both affect inventory. Second, conditions are identified that indicate when networks involving direct shipments between many origins and destinations can be analyzed on a link-by-link basis. Finally, a simple optimization method is developed that simultaneously determines optimal routes and shipment sizes for networks with a consolidation terminal and concave cost functions. This method decomposes the network into separate sub-networks, and determines the optimum analytically without the need for mathematical programming techniques.     

Private tollroads in urban areas

Governments of all persuasions are increasingly seeking the participation of the private sector in the supply of transport facilities and services. Private sector participation in the financing, construction, operation and maintenance of infrastructure is considered a serious option in a number of countries in the search for ways of providing much needed investment which would otherwise be deferred. This paper considers some economic and financial problems in the private sector provision of major road infrastructure within urban areas. The main issues are attaching prices (i.e. tolls) to the provision of the service, the value of government rights which are being given up either permanently or temporarily, and the identification required by the promoters of the cost of capital which is essential information in establishing the risk. Broader environmental and equity issues are not addressed. If the approach to establishing a private presence in a previously public supply context is handled properly from the outset, the benefits can be significant. Contrarily however, the prospects could be quite undesirable if badly managed, despite the presence of an extended public purse.requests for offprints