The global imperative for sustainable energy solutions has renewed interest in ambient energy harvesting from civil infrastructure. Road pavement systems, which continuously receive mechanical energy from vehicular loading and thermal energy from solar irradiation, represent an abundant and largely untapped energy reservoir. This paper presents a rigorous comparative study of two principal pavement energy harvesting technologies — piezoelectric transduction and thermoelectric generation (TEG) — evaluating their theoretical performance limits, practical implementation constraints, and quantified energy yield under tropical and sub-Saharan African road conditions. The analytical framework develops the governing piezoelectric constitutive equations for embedded transducer arrays under dynamic axle loading, and the Seebeck-effect thermoelectric model for pavement-embedded gradient generators. Finite element simulations of pavement vibration spectra under a standardised tropical traffic loading profile yield piezoelectric power densities of 2.1 to 13.5 kWh/m²/year depending on traffic volume and road class. TEG modelling using measured pavement temperature gradients recorded at tropical noon (ΔT = 28°C) across material types including Bi₂Te₃ and skutterudite composites predicts thermoelectric yields of 1.0 to 3.4 kWh/m²/year, with bridge decks exhibiting the highest thermal gradients due to their elevated and exposed geometry. A hybrid MPPT (Maximum Power Point Tracking) circuit architecture is proposed that combines both technologies into a unified power management system with a predicted overall system efficiency exceeding 68%. Parametric sensitivity analysis identifies traffic volume, vehicle speed, and ambient temperature as the dominant governing parameters. The study c