This paper explores innovative approaches to sustainable bridge engineering, focusing on cost reduction and durability enhancement in developing nations. Drawing from my successful projects in Uganda and Guinea, where I reduced construction costs by 30% without compromising structural integrity, I will present detailed case studies that highlight the effective application of sustainable materials and techniques. In Uganda, through the use of locally sourced materials and optimized construction processes, I achieved significant cost savings while ensuring long-term durability in rural infrastructure. Similarly, in Guinea, I implemented advanced engineering practices that prioritized resource efficiency, leading to a reduction in project expenses and a strengthened bridge lifespan. The case studies demonstrate how sustainable engineering practices can be tailored to local conditions and still meet global standards for resilient infrastructure. By emphasizing cost-effective materials such as recycled aggregates and low-carbon concrete, and employing techniques such as modular construction and innovative foundation designs, my work offers a blueprint for reducing expenses while enhancing the longevity of infrastructure. The strategies I employed in Uganda and Guinea are adaptable to other developing nations and can be applied globally, including in the U.S., to build durable and sustainable bridges that address both budgetary constraints and environmental considerations. This paper aligns with the broader goals of sustainable infrastructure development by contributing to the global discourse on resource-efficient engineering solutions. The findings support national and international objectives to enhance infrastructure resilience while minimizing environmental impact and construction costs.