Except as otherwise provided in this section, such a bond shall not be required of any public agency or public utility having lawful authority to occupy the highways which is authorized by law to establish or maintain any works or facilities in, under or over any public highway, nor shall the application of any such public agency or public utility for a permit be denied.

The road commissioner may require of any such applicant a bond in a sum not to exceed twenty thousand dollars ($20,000), if such applicant has in fact prior to such application failed to comply with the provisions of this chapter or with the provisions of a previous permit.