hi,

see junior engineer position in railways have separate entrance exams, the exam generally has two steps, cbt 1  and cbt 2,

cbt 1 has syllabus of general aptitude, reasoning, general awareness, general science etc. you may follow rs agarwal books and lucent gks books for practice.

in cbt 1 questions level is bit tougher than cbt 1, the syllabus includes general awareness, physics chemistry , basics of computer applications, basics of environment and pollution control, technical domain wise papers. for technical domain you may follow ssc je questions and previous year rrb je questions. for physics chemistry follow 12th standard books,  you may follow arihant experts books for mcq practice.