Within fifteen days from the publication of such notice, the department shall post signs along and approximately on the boundaries delineated on such map in conspicuous places and at intervals of not more than one-fourth of a mile, and in no event no less than three signs. Such signs shall bear in letters at least one inch high the words “Highway Line” and in smaller print shall state:
(a) All the information required in the notice provided for in section 864.
(b) The date of the publication of such notice.