Section 9. The department of highways may designate any state highway or part thereof as a through way and may designate intersections or other roadway junctions with state highways at which vehicular traffic on one or more roadways should stop or yield and stop before entering the intersection or junction, and the department may, after notice, revoke any such designation. The department of highways on any state highway or part thereof so designated as a through way, or on any way where the department has designated such way as intersecting or joining with a state highway, shall erect and maintain stop signs, yield signs and other traffic control devices.

The local authorities of a city or town authorized to enact ordinances or by-laws, or make rules, orders or regulations under the provisions of section twenty-two of chapter forty may in accordance with the provisions of section two of chapter eighty-five of the General Laws, including department approval when required, designate any way or part thereof under the control of such city or town as a through way and may designate intersections or other roadway junctions at which vehicular traffic on one or more roadways shall stop or yield and stop before entering the intersection or junction, and may, after notice and like department approval, when required, revoke any such designation. Such local authorities of a city or town having control of any way or part thereof so designated as a through way shall erect and maintain stop signs, yield signs and other traffic control devices at such designated intersections or junctions.

Except when directed to proceed by a police officer, every driver of a vehicle approaching a stop sign or a flashing red signal indication shall stop at a clearly marked stop line, but if none, before entering the crosswalk on the near side of the intersection, or, if none, then at the point nearest the intersecting roadway where the driver has a view of approaching traffic on the intersecting roadway before entering it. After having stopped, the driver shall yield the right of way to any vehicle in the intersection or approaching on another roadway so closely as to constitute an immediate hazard during the time when such driver is moving across or within the intersection or junction of roadways.

The driver of a vehicle approaching a yield sign shall in obedience to such sign slow down to a speed reasonable for the existing conditions and, if required for safety to stop, shall stop at a clearly marked stop line, but if none, before entering the crosswalk on the near side of the intersection, or, if none, then at the point nearest the intersecting roadway where the driver has a view of approaching traffic on the intersecting roadway before entering it. After slowing or stopping, the driver shall yield the right of way to any vehicle in the intersection or approaching on another roadway so closely as to constitute an immediate hazard during the time such driver is moving across or within the intersection or junction of roadways; provided, however, that if such a driver is involved in a collision with a vehicle in the intersection or junction of roadways, after driving past a yield sign without stopping, such collision shall be deemed prima facie evidence of his failure to yield the right of way.

The driver of a motor vehicle shall not cross or enter an intersection, which it is unable to proceed through, without stopping and thereby blocking vehicles from travelling in a free direction. A green light is no defense to blocking the intersection. The driver must wait another cycle of the signal light, if necessary.

For the purposes of this section the word, ''vehicle'', shall include a trackless trolley.

Any person violating the provisions of this section shall be punished by a fine not to exceed $150 for each offense.