Reliability/vulnerability Versus Cost/benefit

Reliability/vulnerability Versus Cost/benefit


J Husdal, Molde University College, NO




The reliability of the transportation network is a factor that is only seldom looked at in cost-benefit analyses. For the most part, saved travel time is what drives the policy of the decision makers, increased reliability is as a rule not a subject for closer evaluation; it is simply taken for granted. A more detailed analysis of the reliability in a road network can assist in bringing a new perspective to cost/benefit-analyses, where the question of whether travellers and goods indeed can traverse the network and thus arrive at their destination is given more weight than in traditional analyses.


This paper investigates a range of the most typical factors that can affect the reliability and vulnerability of the transportation infrastructure and describes a framework for how these factors both could and should be used in a cost/benefit-analysis. It presents an overview of the parameters that contribute to reliability and vulnerability and how the influence of the individual parameters can be used as a measure of reliability and vulnerability. The paper seeks to establish a link between the terms reliability/vulnerability and cost/benefit and describe reliability and vulnerability in terms of cost and benefit and vice versa. The paper shows how reliability and vulnerability can be used as a parameter for locating new businesses and as a parameter in aiding decision-making for new and existing transportation projects.

Examples of factors that are/were investigated: ? Critical paths ? Risk of disruption ? Availability of alternative routes ? Cost of rebuilding ? Closures and downtime ? Hazardous materials transport ? Traffic safety ? Operations and maintenance ? Emergency preparedness ? Global climate changes

The henceforth research investigates the minimum standards of reliability that different types of transport may have, suggesting that different users of transportation means, i.e. goods versus persons, have different requirements with regards to their transportation needs. In the end, case studies will be used to demonstrate the economical consequences of varying reliability, and thus disruptions, to different businesses. Finally, reliability will be used as a parameter for locating new businesses and as a parameter in aiding decision-making for new and existing transportation projects. Wherever possible, this research will also highlight the tools that can be utilised in order to both analyse and visualise the reliability and vulnerability of transportation networks. Albeit the methodology and models in this project will be developed on the basis of a road network, it will also be transferable to other transportation sectors, such as air and rail.

Expected results:

The main goals of the project are:

*To establish a methodology for aggregating a reliability index for a road network.
*To establish the minimum requirements of reliability that pertain to different modes of transport, i.e. persons versus goods, or between different types of goods.
*To analyse how reliability-based cost/benefit-analyses can assist in the decision-making process for existing and planned road development projects.


It is an explicit goal that this research shall serve as a model for any transportation and community planning that has the reduction of vulnerability as its main objective. By applying the results of this research it is hoped that both the private and the public sector will save future expenditures caused by network disruptions and poor planning decisions. A less cost-imposing transportation system is nonetheless not the only objective of this research. It must be kept in mind that cost/benefit analyses, no matter how detailed they are and no matter how economically correct the arguments may be, these arguments must by all means not be (mis)taken for politically correct arguments one way or the other. By adding more factors to the traditional equations of reliability it is hoped that future transportation planners and professionals will not only consider economical arguments, but also dare to take on political statements that are in opposition to factual costs and benefits. This is possibly only when these statements are backed up by a full evaluation of the factors that make up the reliability and vulnerability of our infrastructure system.


Association for European Transport