Section 6. Any public way which has been spread with tar, oil or similar substance, shall, within three hours thereafter, be covered with sand, gravel, peastone or other similar material in such manner as to render the way safe for travel. But such way may be so treated without being so covered if the tar, oil or other similar substance is first applied to not more than one half of the traveled width of the way, and such portion becomes safe for travel before the remaining part of the way is similarly treated, or if there is a reasonably safe and convenient alternate route or detour which has not been so treated, or if so treated has been rendered safe for travel as herein provided. Violation of any provision of this section shall be punished by a fine of not less than ten nor more than one hundred dollars.