The Bicycle Bicycle Passing Clearance Sign (R4-19) was added to the latest edition of the MUTCD, the 11th edition Dec 2023 (here’s the bicycle chapter: part 9 .pdf). The sign is not presently in in Arizona’s MOAS (Manual of Approved Signs). — I’m not sure what’s up with that since Arizona state law does have a specific minimum passing law as required by the standard in order to use the sign.
Here is some background on how the Passing Clearance sign was developed on its way to be added to the MUTCD.
Section 9B.15 Bicycle Passing Clearance Sign (R4-19) Option: The Bicycle Passing Clearance (R4-19) sign (see Figure 9B-1) may be used in jurisdictions that have defined in law or ordinance a specific clearance to be provided by motor vehicles when they pass bicycles. The specific clearance displayed on the Bicycle Passing Clearance (R4-19) sign may be adjusted to reflect the applicable law or ordinance. Standard: The Bicycle Passing Clearance (R4-19) sign shall not be used in jurisdictions that do not have a specific passing clearance to be provided by motor vehicles passing bicycles, as defined in law or ordinance. Guidance: The Bicycle Passing Clearance (R4-19) sign should not be used on roadways with bicycle lanes or with shoulders usable for bicycle travel.
I consider the messaging of three foot rules to be weak compared to the more direct and unambiguous statement that bicyclists are allowed to use the full lane, so read on…
Bicycles Allowed Use of Full Lane Sign (R9-20)
The “allowed” sign, (R9-20) supersedes the older “may” sign (R4-11, often referred to as BMUFL for short) in the 11th edition. I was not aware of this change and have no idea where it came from; and I’m sortof annoyed by it. I preferred the “change lanes to pass” optional placard which is apparently GONE. Curiously the older sign, as well as the optional placard, continue to be available in Arizona’s MOAS (Manual of Approved Signs); and the newer sign IS NOT in the Az MOAS, as of this writing March 2026… while the BMUFL (see below) are still there? What’s the plan for that?
Other Bike-related signs
I didn’t have time but other signs of interest are in the warning (yellow/diamond shaped) section: Bikes in street / in road. Bikes Merge.
Bicycles May Use Full Lane (MUTCD 2009 edition)
For posterity, here’s an image of a Bicycle May Use Full lane R4-11 sign (along with the Arizona-optional plaque) that appears in previous editions of MUTCD, as well as currently (as of this writing March 2026) in Arizona’s MOAS (Manual of Approved Signs)
Section 9B.14 Bicycles Allowed Use of Full Lane Sign (R9-20) Support: 01 The Uniform Vehicle Code (UVC) defines a “substandard width lane” as a “lane that is too narrow for a bicycle and a vehicle to travel safely side by side within the same lane.” Option: The Bicycles Allowed Use of Full Lane (R9-20) sign (see Figure 9B-1) may be used on roadways where no bicycle lanes or adjacent shoulders usable by bicycles are present and where travel lanes are too narrow for bicycles and motor vehicles to operate side-by-side. The Bicycles Allowed Use of Full Lane sign may be used in locations where it is important to inform road users that bicyclists might occupy the travel lane. Section 9E.09 describes a shared-lane marking that may be used in addition to or instead of the Bicycles Allowed Use of Full Lane sign to inform road users that bicyclists might occupy the travel lane.
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Signage is great, but the actual infrastructure needs to facilitate the multiple uses of roadways. Specifically, I concerned with the striped “buffer zones” I see on roadways particularly in Scottsdale and Phoenix. These buffers never provide a 3-foot clearance to the left edge of the bike lane, and they often steel real estate from the bike lane further narrowing its useful width. Besides, how are these buffers interpreted in relation to statute? Who has right of way in them? If a collision occurs in the buffer, how does ARS 28-735 apply? Do municipalities treat these buffers differently? I think a better solution would be to paint a green stripe 3 feet into the right hand travel lane as measured from the left bicycle lane line and provide signage indicating passage left of that line is required when a bicycle is present.
By not allowing the signs next to bike lanes, it encourages motor vehicles to see the entire travel lane as their right, while passing bikes in a bike lane within inches of them. Really dumb.
The whole 3-ft thing hasn’t been very helpful in my view. For example, consider that many police believe that that law does not apply when there are separate Lanes, see e.g. point number 6 here https://azbikelaw.org/tempe-bfc/
And overall, there’s been virtually no 28-735 tickets issued except as a result of crashes (since the amount of clearance being less than 3 ft was inescapable), despite the law having been on the books for decades.
Precisely the point! These insuficient buffer lanes can be interpreted as “adequate” separation, regardless of the plain language of the law. These grand experimental bicycle infrastructure schemes by well-meaning trafic planners only increase the hazard and diminish the due rights o cyclists. The only fix I see is legislative, but I’m not holding my breath.
Here’s a pretty good roundup of mutcd part 9 stuff:
https://www.facebook.com/groups/roadbikecycling/posts/1790810918133499/
There are no penalties for passing too close if the motorist does not cause a collision.
28-735. Overtaking bicycles; civil penalties
A. When overtaking and passing a bicycle proceeding in the same direction, a person driving a motor vehicle shall exercise due care by leaving a safe distance between the motor vehicle and the bicycle of not less than three feet until the motor vehicle is safely past the overtaken bicycle.
B. If a person violates this section and the violation results in a collision causing:
1. Serious physical injury as defined in section 13-105 to another person, the violator is subject to a civil penalty of up to five hundred dollars.
2. Death to another person, the violator is subject to a civil penalty of up to one thousand dollars.
C. Subsection B of this section does not apply to a bicyclist who is injured in a vehicular traffic lane when a designated bicycle lane or path is present and passable.