The department shall exercise a reasonable discretion in acting on applications of utilities for permits to occupy freeways for longitudinal locations of facilities, as may be required for the proper discharge of their services to the public. The department may, however, refuse to grant any applications for any such longitudinal installation which would be inconsistent with public safety or the continued unobstructed use of the freeway for vehicular traffic, or for any type of utility structure inconsistent with the aesthetic values of any landscaped freeway within, or approaching within one mile of, the limits of any city.