Comparative Life Cycle Assessment of Carbon Emissions from Road Reconstruction Methodologies in South Sudan, 2021–2026

{ "background": "Road infrastructure reconstruction in fragile states presents significant environmental challenges, with carbon emissions from construction activities being a critical yet understudied aspect. The post-conflict context of South Sudan, characterised by urgent reconstruction needs and limited environmental governance, necessitates a rigorous assessment of the climate impacts of different engineering methodologies.", "purpose and objectives": "This study aims to quantify and compare the life cycle carbon emissions associated with conventional full-depth reclamation and a modified in-situ stabilisation technique for road reconstruction. The objective is to identify the methodology with the lower carbon footprint under local operational constraints.", "methodology": "A process-based Life Cycle Assessment (LCA) was conducted, following ISO 14040/44 standards, for two functionally equivalent road sections. System boundaries included material production, transport, on-site construction, and machinery use. Emissions were modelled using a linear regression framework: $Ei = \\beta0 + \\beta1 Mi + \\beta2 Ti + \\epsiloni$, where $Ei$ is total emissions, $Mi$ is material intensity, and $Ti$ is transport distance. Uncertainty was propagated using Monte Carlo simulation.", "findings": "The modified in-situ stabilisation technique yielded a mean reduction of 38% in embodied carbon per kilometre compared to conventional reclamation (95% confidence interval: 32% to 44%). This reduction was primarily driven by a 65% decrease in imported aggregate requirements, outweighing the increased emissions from stabiliser production and application.", "conclusion": "The modified in-situ methodology offers a substantially lower-carbon pathway for road reconstruction in this specific operational context, demonstrating that material sourcing and transport are the dominant factors in the project carbon footprint.", "recommendations": "Project planners and environmental regulators should prioritise specifications that minimise the transport of virgin materials and promote the use of locally available, stabilised in-situ materials. Further development of region-specific emission factors for construction materials is also recommended.", "key words": "Life Cycle Assessment,