The capital cost aspects of the environmental impact of new highways in association with the new design technique: the commercial route methodology

This work addresses the capital cost implications of environmental impact allied to new highways. Those environmental impact considerations which are capable of being evaluated in terms of capital cost are distinguished from those which are concealed and cannot be evaluated using monetary values. The new design technique, the commercial route methodology (CRM), has been developed to evaluate in capital cost terms the concealed and unquantifiable impacts inter alia, visual intrusion, visual obstruction, effects on agriculture, ecological concern, heritage and conservation areas and aesthetic aspects. The work studies the capital costs associated with environmental impact mitigation measures built into highway schemes located both internationally and in the UK. This approach identifies and analyses the capital cost of mitigation measures taken to ameliorate those implicit and identifiable environmental impacts - notably additional earthworks, noise barriers and insulation, landscaping and special treatments. In order to evaluate the cost of those impacts which are concealed and unquantifiable, CRM was applied to a range of approved highway schemes of a Highway Authority - Derbyshire County Council. In each case, a commercial route was successfully derived, and the hitherto unquantifiable aspects of environmental impact were evaluated. In this connection the application of CRM provided a figure of approximately 18% which, in Derbyshire, represents a sum in excess of £4m. Translated nationally this represents a sum of over £2bn during the period 1976/77 to 1985/86. CRM is, thus, available for integration into the current highway design method to give a ’baseline’ cost from which engineers, politicians, accountants and members of the public can assess and understand the capital cost of mitigating environmental impacts resulting from new highways; while providing additional data for public consultation and inquiry procedures, decision-making and scheme-ranking and appraisal.