The construction of road infrastructure is essential for the development of a locality. This study on the bypass of the Melong-Carrefour Yimo section of National Road N°5 in Melong was carried out to assess the socio-economic and environmental impact of this bypass in the town of Melong. The town of Melong is crossed by National Road N°5, which serves the West and Littoral regions. This road was rerouted in 1978 at Melong. The high-altitude terrain on which the old route was built made the road very long and winding, with gradients that were sometimes very steep. The new section is less winding and wider, with more or less heavy traffic depending on the season. The new route has not only led to the spatial expansion of the town of Melong and the development of new income-generating activities in the new trading points, but also to a considerable reduction in economic activity in the town center and other districts along the old route.