RRB-Group D Eligibility Requirements & Selection process

POST under Group B: Class II Recruitment into Group B positions is unconventional, primarily based on the promotion of individuals from Group C roles. For instance, in the Civil Engineering Department, 70% of positions are filled through a selection process involving a written examination and interviews with non-ministerial Group C employees from the same department. The remaining 30% are filled by Group C employees who have served for a minimum of five years in the same grade and have qualified for a departmental competitive exam. Group C employees, depending on their administrative responsibilities, can hold either non-gazetted or gazetted positions
To know more: https://blog.sfrbc.com/jobs/government-jobs/central/exam/railway-recruitment-board/railway-recruitment-board-rrb/