As a career option, Indian Railways is definetely worth considering for any bright young graduate, who is all set on choosing a career. So how does one join the Indian Railways?
1) After completing Higher Secondary School (Standard XII), one can appear for the Special Class Railway Apprentice (SCRA) examinations conducted by the Union Public Service Commission(UPSC), Dholpur House, New Delhi. This exam is extremely competitve, as there are a limited number of vacancies available (16 or so, when I wrote this examination circa 1993. The number of seats on offer as of now, might be different).
Succesful candidates join as technical apprentices (Special Class) and are sent to the Indian Railways Institute of Mechanical Engineering (not sure about the exact name) at Jamalpur. Here, they are put through a four(?) year technical course, and I guess they have to clear the examinations conducted by the Institution Of Engineers. Once cleared, they are directly recruited as officers under the cadre of Indian Railways Service Of Mechanical Engineers (IRSME).
Officers coming via the SCRA route have a distinct advantage over the others -- they climb the corporate (read railway) ladder rather quickly, compared to their counterparts who join after clearing IES. Many of them go on to become General Managers & Members of the Railway Board. Of course, to be come a GM, they have to put in stint as a DRM.
2) After completing Engineering, candidates aspiring for a job with IR have to clear the Indian Engineering Services (IES) examinations, conducted by the UPSC. These examinations are tough, as they question you on the technicals of the subjects which you had studied in engineering. The competition is hectic, as only the top cream of the successfull candidates get an offer from the railways. Other have to settle for CPWD, MES, NHAI etc...
Candidates from Civil, Mechanical, Electronics, and Electrical branches of engineering, are inducted into the railways into their respective cadres (Indian Railways Service Of Civil/Mechanical/Electrical/Telecom Engineers respectively). They all are given training at their respective institutions. (For IRSE engineers, it is the Indian Railways Institute Of Electrical Engineering (IREEN) at Nashik, and the Railway Staff College, at Vadodara (common for all).
3) You can also get into the Railways by appearing for the Civil Services examinations. If you get a good rank, you might opt for the Indian Railways Traffic Service (IRTS), or the Indian Railways Accounts Service (IRAS).
4) For technical level posts and lower level posts, the regional Railway Recruitment Boards conduct regular examinations for the posts of Drivers, Assistant Drivers, Stations Masters, Section Engineers etc.
5) Meritorious sportspersons are also encouraged to join the Indian Railways under the Sports Quota.
6) Doctors and surgeons can join the Railways, and they come under the Indian Railways Medical Service (IRMS) cadre. Railways have full-fledged hospitals at the divisional level & at zonal headquarters. Some of them are famous (PER railway hospital is famous for heart surgery).
7) On humanitarian grounds, if a railway employee dies while in active service, the next of kin might be given a job on compassionate grounds (breadwinner case).
And at the lowest level, helpers or attendants functioning as bungalow peons might be eventually absorbed into regular service as khalasis and helpers.