Structural Optimisation of Lattice Transmission Towers for the West African Power Pool: A Policy Analysis for Material Reduction Using High-Strength Weathering Steel

{ "background": "The expansion of the West African Power Pool necessitates a vast network of transmission lines, creating significant demand for steel lattice towers. Conventional design practices and materials lead to high material tonnage, escalating costs and environmental impact. This analysis examines the potential for structural optimisation to address these challenges within the regional policy framework.", "purpose and objectives": "This policy analysis aims to evaluate the feasibility and implications of adopting high-strength weathering steel (HSWS) in the structural optimisation of lattice transmission towers. The primary objective is to quantify potential material savings and assess the policy interventions required to facilitate this technological shift across member states.", "methodology": "A comparative structural analysis was conducted using a non-linear finite element model to optimise tower geometries. Material properties for HSWS (S460W) were compared with conventional steel (S355J2). The optimisation was constrained by ultimate limit state and serviceability limit state requirements per IEC 60652. A generalised linear model, $Yi = \\beta0 + \\beta1 X{i1} + \\beta2 X{i2} + \\epsiloni$, where $Y$ is mass reduction, $X1$ is yield strength, and $X_2$ is a design code compliance indicator, was used to estimate savings. Policy analysis drew on documentary review of regional energy and industrial strategies.", "findings": "Structural optimisation using HSWS yields a mean material reduction of 15.2% (95% CI: 14.1% to 16.3%) for a standard double-circuit tower in the analysed configuration. This reduction is robust to variations in loading assumptions. The principal policy barrier identified is the absence of specific material standards for HSWS in existing national building codes, which creates regulatory uncertainty for utilities and manufacturers.", "conclusion": "Integrating high-strength weathering steel into transmission tower design is a technically viable strategy for substantial material reduction, supporting cost-efficient grid expansion. Realising this potential requires targeted policy action to update regulatory frameworks and