This exploratory study aimed to examine the validity of the sustainability evaluation model suggested and the sustainability of the standard gauge railway (SGR) construction project in Africa’s developing countries with Tanzania as a case study. By using the proposed railway sustainability evaluation model, the researchers collected data from 300 people, which included workers in the project and people living or conducting businesses along the route of the first phase of the project (Dar-es-salaam to Morogoro). Data was collected using semi-structured questionnaires and analyzed using the structural equation model (SEM) technique and correlation analysis. The findings validated the model used to be efficient in railway sustainability evaluation, and also, the researchers were able to realize from the data collected that the first phase of the SGR in Tanzania is sustainable for development. The study suggests encouraging and collaborating with local agencies to improve local railway maintenance and operations skills in order to ensure the project’s long-term viability and extension.