No person shall drive a motor vehicle at such a slow speed as to impede or block the normal and reasonable movement of traffic except when reduced speed is necessary for safe operation or in compliance with law or except when the vehicle is temporarily unable to maintain a greater speed due to a combination of the weight of the vehicle and the grade of the highway.
(a) Except as provided in paragraph (b), a driver of a vehicle shall not enter an intersection controlled by a traffic-control signal until the driver is able to move the vehicle immediately, continuously, and completely through the intersection without impeding or blocking the subsequent movement of cross traffic.
(b) Paragraph (a) does not apply to movement of a vehicle made:
(1) at the direction of a city-authorized traffic-control agent or a peace officer;
(2) to facilitate passage of an authorized emergency vehicle with its emergency lights activated; or
(3) to make a turn, as permitted under section 169.19, that allows the vehicle to safely leave the intersection.
(c) A violation of this subdivision does not constitute grounds for suspension or revocation of the violator's driver's license.