The modernization process during Reza Shah's era yield to fundamental changes in the political, economic, social, and cultural systems of society. The expansion of communication routes and the construction of the trans-Iranian railway were some of the issues that drew Reza Shah’s attention during the modernization process.The construction of the northern railway was accompanied by numerous challenges and difficulties that engaged the workforce and the residents of the areas through which the railway passed. Through documentary and library studies and using a descriptive-analytical method, this study seeks to reflect the workers’ concerns and complaints and the consequent suffering, as well as the problems inhabitants encountered in their dealing with foreign companies involved in the construction of the railway, as one of the modernization processes during the Reza Shah era in the cities of Mazandaran.The findings indicate that healthcare, compensation payment methods, the employment of European rather than Iranian labors, financial disputes with Kampsax company, and the loss of farmlands and rice field were some of the most significant concerns and worries of the workforce and local population along the northern railway. Further investigations reveal that these issues, although present, were not as severe as stated in some documents. In response to numerous issues which caused workers’ and the public’s dissatisfaction, the government and the company introduced some measures; however, in many cases, workers had complaints that were followed up by the Ministry of Roads, Parliament, and the Ministries of Justice and Finance.