(1) A railway servant whose employment is essentially intermittent shall not be employed for more than seventy-five hours in any week.
     (2) A railway servant whose employment is continuous shall not be employed for more than fifty-four hours a week on an average in a two-weekly period of fourteen days.
     (3) A railway servant whose employment is intensive shall not be employed for more than forty-five hours a week on an average in a two-weekly period of fourteen days.
     (4) Subject to such rules as may be prescribed, temporary exemptions of railway servants from the provisions of sub-section (1) or sub-section (2) or sub-section (3) may be made by the prescribed authority if it is of opinion that such temporary exemptions are necessary to avoid serious interference with the ordinary working of the railway or in cases of accident, actual or threatened, or when urgent work is required to be done to the railway or to rolling stock or in any emergency which could not have been foreseen or prevented, or in other cases of exceptional pressure of work:
     Provided that where such exemption results in the increase of hours of employment of a railway servant referred to in any of the sub-sections, he shall be paid overtime at not less than two times his ordinary rate of pay for the excess hours of work.