57. (1) The Minister may, for reasons of traffic safety, reduce or increase the speed limits provided in subsection 3 of section 56 for all motor vehicles or for certain categories of them.
(2) The installation of official traffic signs is proof of the decision of the Minister. The approximate date and place of the installation of such a traffic sign, or of its removal, if such is the case, must be entered in a register kept by the Minister.
(3) Notwithstanding subsection 3 of section 56, no person shall drive at a speed exceeding that indicated on the official traffic signs installed under subsection 2 of this section.
(4) The exercise of the power provided in subsection 1 renders inoperative every contrary or inconsistent provision of any by-law of a municipal council or of any by-law, resolution or ordinance of the competent authority of an urban or regional community.