(1) A person who without lawful authority or excuse, the proof of which lies on him or her, commits any of the following nuisances, namely—
(a) being under a legal duty to provide for the construction, maintenance, or repair of any public works, fails to perform such duty;
(b) causes any obstruction to the public use of any public works, so as to deprive the public of the benefit of it,
is liable on summary conviction to imprisonment for one year or to a fine not exceeding $1,000.
(2) No such nuisance is excused on the ground that it causes some convenience or advantage.
(3) A person is not liable for obstructing the public use of any public works by reason only of his or her being a party to any meeting or assembly in, or upon, or near any public works, unless the purposes of such assembly are or include the obstruction of the public by force or threats or show of force.