The number of vacancies filled every year by IES is maximum for Civil engineers.You can definitely apply for Engineering services after Civil engineering.The age limit should be 21-30years and you should have a valid and recognised B.Tech/BE degree.You will have 5papers of 200 marks each.1st paper is of GS and Current Affairs.2nd day you will have 2 papers objective civil engineering.3rd day you will have 2 papers subjective engineering.After you qualify in all these papers you will be called for interview and then final selection.Check out website of UPSC for previous papers etc to get the level of exam