There exist many approaches aimed at appraising and evaluating the socio-economic feasibility of surface transportation projects such as road and railway infrastructure. Cost benefit analysis (CBA) and multicriteria assessment (MCA) have been implemented by many governments over a long period of time to support policy-making decisions. In the last few years these approaches have progressively moved towards incorporating externalities such as emissions, noise, congestion and accidents in their methodologies. However, up to now little has been done to incorporate sustainability criteria, into the optimal engineering design of infrastructure facilities.

Investment decisions dealing with road infrastructure are crucial for society because of the sunk-cost nature of the investment costs. Infrastructure design characteristics (alignment, pavement, etc.) have an effect on the operation costs for the vehicles and their emissions.

This research lies in the theoretical that, for each road, there is an optimum design that optimizes the life-cycle cost. The core objective of this research is to develop an instrument to help decision-makers select the most adequate road infrastructure design from the point of view of sustainability –social, environmental and economic across the life-cycle. To that end, we will build a tool for ensuring the effective incorporation of all sustainability issues in the design of road projects and investment decisions.