A multi-criteria decision-making framework for sustainable road transport systems: Integrating stakeholder-cost-environment-energy for a highway case study in United Arab Emirates

Existing lifecycle assessment models narrowly concentrate on limited parameters, disregarding system ecology and multi-stage stakeholder integration with sequestered analyses. Assimilation of new transport technologies with traditional design-bid-build decision-making paradigm should acknowledge sustainability triple-bottom-line social, cost, and environmental impacts, across all lifecycle stages for a system-wide optimisation. This study presents a multilevel framework to evaluate road transport system projects utilising 1) stakeholder engagement for flexibility in establishing key performance indicators, 2) passenger surveys to identify what encourages mode choice towards public transport, 3) microsimulation models, lifecycle cost and lifecycle analysis for quantitative assessment, 4) analytic hierarchy for qualitative assessment, and finally 5) multi-criteria modelling with stakeholder expert group preferences. Framework is applied to a 5-lane dual carriageway project in Abu Dhabi, analysing eight virgin and recycled material-based and public transport service alternatives. Study revealed the significance of saved user time, reduced fuel consumption during use phase and vehicle operational costs as the highest lifecycle impact generators. The total sustainability performance across the lifecycle for all alternatives was affected by traffic gridlock formation due to traffic growth in later years and lack of traffic load reduction strategies. Results showed that an autonomous vehicle-based bus rapid transit service coupled with recycled material to construct the road significantly reduced lifecycle cost (51.1%), energy (55.6%) and pollutant (54.5%-CO2, 49.7%-NOx, 24.1%-PM) burdens. It exhibited effectiveness of system choice using lifecycle assessment over the typically fragmented project planning and evaluation approach. Overall, framework exhibited robustness against unit cost and LCI uncertainties, fuel distribution assumptions, discount rate, and indicator weights variations based on priorities of different stakeholder groups.