(1) The driver of any vehicle, every bicyclist, and every pedestrian shall obey, and the operation of every personal delivery device shall follow, the instructions of any official traffic control device applicable thereto, and as specified in this chapter, placed in accordance with the provisions of this chapter, unless otherwise directed by a traffic or police officer, subject to the exception granted the driver of an authorized emergency vehicle in this chapter.

(2) No provision of this chapter for which official traffic control devices are required shall be enforced against an alleged violator if at the time and place of the alleged violation an official device is not in proper position and sufficiently legible or visible to be seen by an ordinarily observant person. Whenever a particular section does not state that official traffic control devices are required, such section shall be effective even though no devices are erected or in place.

(3) Whenever official traffic control devices are placed in position approximately conforming to the requirements of this chapter, such devices shall be presumed to have been so placed by the official act or direction of lawful authority, unless the contrary shall be established by competent evidence.

(4) Any official traffic control device placed pursuant to the provisions of this chapter and purporting to conform to the lawful requirements pertaining to such devices shall be presumed to comply with the requirements of this chapter, unless the contrary shall be established by competent evidence.

(2)(a) Except when directed to proceed by a duly authorized flagger, or a police officer, or a firefighter vested by law with authority to direct, control, or regulate traffic, every driver of a vehicle approaching a stop sign shall stop except as provided in (b) of this subsection at a clearly marked stop line, but if none, before entering a marked 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 the roadway, and after having stopped 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.

(3) 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 a marked 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 the roadway, and then 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, 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 the driver's failure to yield right-of-way.

(4)(a) When right-of-way has not been yielded in accordance with this section to a vehicle that is a vulnerable user of a public way, a driver of a motor vehicle found to be in violation of this section must be assessed an additional fine equal to the base penalty assessed under RCW 46.63.110(3). This fine may not be waived, reduced, or suspended, unless the court finds the offender to be indigent, and is not subject to the additional fees and assessments that the base penalty for this violation is subject to under RCW 2.68.040, 3.62.090, and 46.63.110.

In addition to the points of intersection of any public highway with any arterial public highway that is constituted by law or by any proper authorities of this state or any city or town of this state, the state department of transportation with respect to state highways, and the proper authorities with respect to any other public highways, have the power to determine and designate any particular intersection, or any particular highways, roads, or streets or portions thereof, at any intersection with which vehicles shall be required to stop before entering such intersection. Upon the determination and designation of such points at which vehicles will be required to come to a stop before entering the intersection, except as provided in RCW 46.61.190, the proper authorities so determining and designating shall cause to be posted and maintained proper signs of the standard design adopted by the state department of transportation indicating that the intersection has been so determined and designated and that vehicles entering it are required to stop, except as provided in RCW 46.61.190. It is unlawful for any person operating any vehicle when entering any intersection determined, designated, and bearing the required sign to fail and neglect to bring the vehicle to a complete stop before entering the intersection, except as provided in RCW 46.61.190.

(1) Every person riding a bicycle upon a roadway shall be granted all of the rights and shall be subject to all of the duties applicable to the driver of a vehicle by this chapter, except as to special regulations in RCW 46.61.750 through 46.61.780, except as provided in RCW 46.61.190, and except as to those provisions of this chapter which by their nature can have no application.

In order to provide safety at intersections on the state highway system, the department may require persons traveling upon any portion of such highway to stop before entering the intersection, except as provided in RCW 46.61.190. For this purpose there may be erected a standard stop sign as prescribed in the state department of transportation's "Manual on Uniform Traffic Control Devices for Streets and Highways." All persons traveling upon the highway shall come to a complete stop at such a sign, except as provided in RCW 46.61.190, and the appearance of any sign so located is sufficient warning to a person that he or she is required to stop. A person stopping at such a sign shall proceed through that portion of the highway in a careful manner and at a reasonable rate of speed not to exceed twenty miles per hour. It is unlawful to fail to comply with the directions of any such stop sign, except as provided in RCW 46.61.190. When the findings of a traffic engineering study show that the condition of an intersection is such that vehicles may safely enter the major artery without stopping, the department or local authorities in their respective jurisdictions shall install and maintain a "Yield" sign.