§ 16. Vacations. The board of transportation shall grant to every employee under its supervision, who shall have been in such employ for at least one year, a vacation of not less than two weeks in each year and for employees in such employ less than one year, a vacation pro-rated on the basis of one day per month while in such employ, and for such further period of time as in the opinion and judgment of such board, the duties, position, length of service and other circumstances may warrant, at such time as such board may fix. During such vacations such employees shall be allowed the same compensation as if actually employed.