Issues of reliability and vulnerability are mormally not considered a matter of evaluation in traditional cost-benefit analyses. Consequently, traditional cost-benefit analyses are lacking decision variables that may be important. This paper looks beyond the abstract science of vulnerability assessments, and discusses some of the factual influences and network attributes that contribute to the vulnerability of transport networks. The influences of the individual attributes are then examined as a measure of the vulnerability of a transport network. Although reliability can be defined by absolute numbers, vulnerability, by its very nature can not. The paper further outlines a framework for developing a methodology that to incorporate reliability and vulnerability as parameters for decision-support in a cost-benefit analysis. In doing so, this paper seeks to establish a link between the terms reliability/vulnerability and cost/benefit and seeks to describe reliability and vulnerability in terms of cost and benefit. Cost-benefit evaluations are part of many decision making processes, and it is argued that vulnerability assessments likewise should play an important role as input to these processes.

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