This book takes an in-depth look at the impact of transportation infrastructure on economic growth and regional development. Highlighting the complexity and nuance of this relationship, the authors explore the multiple dimensions of the interaction between transport and the economy. After exploring macroeconomic relationships and the main economic theories on the subject, the book turns to cost-benefit analysis and the socio-economic implications of transportation projects. It highlights the importance of spatial dimensions, focusing on the impact of transport on the location of economic activities and regional inequalities. The authors also compare the perspectives of academic and non-academic literature, particularly with regard to the effects of high-speed lines. Particular emphasis is placed on the Moroccan context, where major infrastructure investments are underway. The book analyzes socio-economic evaluation models in France and Morocco. The aim is to provide a rich analytical framework for optimizing transport infrastructure decisions.