In this paper, an innovative Engineering Sustainability Policy (ESP) and a new Sustainable Engineering Index (SEI) is proposed on the basis of testing results obtained within the context of the DN16 project in the State of Qatar, the largest project of the existing C2 Programme which represents the biggest sewage, drainage, and roads development programme worldwide. The ESP has been developed through a joint effort and active participation by the authors from Ashghal (PWA), the government entity, Arcadis, the consultant (acting from a design and site supervision perspective) and contractor (CCC). The policy refers to the general pillars for sustainable engineering defined by the Institution of Civil Engineers (ICE), which are environmental, financial, and social. Also, it fully aligns and complies with Ashghal and Qatar Vision 2030 regarding sustainability. The proposed policy takes into account a number of areas and aspects across all distinct phases of a project life-cycle, from master-planning to the design phase, from construction to handing over phases. During the testing phase for both the policy and index, the project's CAPEX and OPEX have been monitored throughout and, by adopting the new proposed approach, a decrement of the overall costs has been observed. The new proposed policy and index shall comply with international regulation over sustainable engineering, however they have been primarily designed to integrate existing Ashghal policies and procedures based over the on-going interaction process between major parties involved. Next step will be to define a refined calibration of the suggested SEI using data from a wider pool of projects from a holistic perspective, i.e. from concept to the handing over phase. The newly proposed SEI may be used as an initial effective tool to monitor the sustainability status of every project by means of qualitative interviews with key project people and managers.