When must I ride my bicycle on the shoulder?
First, it’s important to define what a shoulder is, and isn’t. ” ‘Roadway’ means that portion of a highway that is improved, designed or ordinarily used for vehicular travel, exclusive of the berm or shoulder” §28-601(22). Busier streets are typically divided into one or more travel lanes in each direction, with a solid white stripe, called an edge line (often referred to as a fog line), at the right edge of the rightmost lane. The area to the right of the edge line is the shoulder. Note that not all streets have edge lines. It’s also possible to have a left edge line and a left shoulder, for example on a one-way street or divided road. Note also that the shoulder may or may not be paved, it is simply that region next to the roadway. Most of this discussion tacitly assumes a paved shoulder; however not all shoulders are paved.
A quick word about bicycle lanes: bicycle lanes are not shoulders, and shoulders are not bicycle lanes. Bicycle lanes are usually designed to AASHTO standards, and must be marked according to MUTCD specifications and designated as such by the local authority; this usually involving both a stripe and painted symbol ground markings and (now optional) “bike lane” regulatory signs.
So, designated bike lanes are part of the roadway, whereas shoulders are, by definition, not. See below for More about Bike Lanes.
In Arizona a bicyclist generally may travel on any shoulder — because it is not prohibited by any statute. (Motorists are not explicitly prohibited from driving on the shoulder, either*) However, on controlled-access highways jurisdictions may, and do, restrict bicycle use (§28-733). In particular, ADOT restricts bicyclists on limited-access highways where allowed to the shoulder, and prohibits bicyclists altogether on other, mostly urban, controlled-access highways. Likewise, local authorities may regulate the operation of bicycles on roads under their jurisdiction; although this is uncommon (§28-626 & 627).
Arizona has no mandatory shoulder use law for bicyclists. §28-815A specifies where, laterally, a bicyclist must ride when riding on the roadway. It contains no provisions for requiring removal from the roadway onto any shoulder, ever.
Bicyclists must ride “as close as practicable” to the right hand edge of the roadway when traveling at less than the normal speed of traffic; but only if (among other exceptions) the lane is wide enough to share, and have no general duty to not impede other drivers nor to travel as fast as motorized traffic, that is to say §28-704A and §28-701E are inapplicable to bicyclists because they specifically apply only to drivers of motor vehicles. Drivers of vehicles, which includes bicyclists, on two-lane highways, that is one lane in each direction, have a duty to pull off the roadway, when safe, if impeding five or more vehicles and passing is unsafe (§28-704C). If a shoulder is available and safe (e.g. clear of debris, wide enough to allow a cyclist to completely exit the roadway), a bicyclist under such conditions would be required to leave the roadway and allow traffic to clear.
Typical busier roads in urban settings are multiple lanes in each direction, and as such 28-704C is not applicable. The law presumes that faster traffic can overtake in one of the other available lanes, so bicyclists are never required to leave the travel lane. The Slow driver law, §28-721B, can apply to bicyclists, and only requires the slower traffic to use the right hand lane on any road laned for traffic; all busy urban roads are laned. It never requires any traffic to leave the roadway.
So, in sum, bicyclists except for the caveats mentioned (certain limited-access highways; and under particular conditions on a two-lane highway) are never required to use a shoulder, though many often choose to.
More about Bike Lanes
As explained above, a duly marked and designated bike lane, unlike a shoulder, is part of the roadway and as its name suggests, it is also a lane, albeit one for the “exclusive use of bicycles” (§28-815C). There is no explicit statute requiring a bicyclist to use any bike lane.
Bike lanes are an example of a preferential use lane. Other examples of preferential use lanes are for taxis, buses, and HOV (High Occupancy Vehicles). The type of user the lane is for is not/never required to use it. HOV drivers are not required to use HOV lanes, etc.
Bicyclists moving slower than the normal speed of traffic would be effectively required to use a bike lane if none of the 28-815A exceptions apply; as illustrated in one-road-4-treatments the narrow-lane exception almost always applies on laned roads, because of the way traffic engineers have chosen to design them.
See more about bike lane use requirements here (link to be inserted).
A Last word about shoulders
Remember, not all roads have shoulders, and not all roads with shoulders have paved shoulders. It may well be possible to ride on this shoulder like the one pictured at left, for example with a mountain bike — but it is never required.
Arizona law does not define the term “improved shoulder”. (in contrast, see Texas shoulder laws, mentioned below). Shoulders are just shoulders, and the laws have to work on all types of highways.
Two abreast riding is generally allowed “Persons riding bicycles upon a roadway shall not ride more than two abreast except on paths or parts of roadway set aside for the exclusive use of bicycles.” §28-815B. Note that the number of riders abreast restriction only applies on “the roadway”; as we’ve seen above, a shoulder is not part of a roadway.
The narrow-lane exception in §28-815A(4) “If the lane in which the person is operating the bicycle is too narrow for a bicycle and a vehicle to travel safely side by side within the lane” is generally understood to mean ONE bicycle, and if the exception applies to one bicycle, it also applies to two bicyclists riding abreast. In other words, some lanes will be just wide enough to safely share with one bicyclist; if bicyclists are riding two-abreast in such a lane, they are required to “single up” in the presence of faster traffic. By contrast, when riding in a narrow lane, cyclists may continue to ride two-abreast subject only to the rules already mentioned above.
* §28-729(1) says on laned roads “A person shall drive a vehicle as nearly as practicable entirely within a single lane…”. And §28-721A says that “On all roadways of sufficient width, a person shall drive a vehicle on the right half of the roadway…”; either statute is generally taken to mean when driving on the roadway, a driver must only operate on the right side (i.e. in the correct direction) of the roadway; and not on any shoulder; the shoulder is not a lane. That being said, to the extent that 28-721A and/or 28-729(1) does prohibit drivers of vehicles from operating on the shoulder; SB1218 in 1986 made several changes regarding the operation of bicyclists. Among them, it clarified 28-812 to make clear that bicyclists are permitted to use a shoulder by adding the language “OR UPON A SHOULDER ADJOINING A ROADWAY” (historical footnote; the word ‘upon’ has since been changed to ‘on’, probably just a conforming change).
While Arizona law is mum, In contrast some states get very specific about shoulder usage; consider Texas Transportation Code – Section 545.058. Driving On Improved Shoulder, e.g. allowing drivers to drive on shoulders but only when “necessary and safe”. And furthermore exempting bicyclists from shoulder prohibitions. Also, recently (2012) Delaware amended their law to explicitly state bicyclists are allowed (but not require) bicyclists to use paved shoulders.
Some further references
- Bicyclists are generally granted the same rights and responsibilities as a driver of a vehicle, see §28-812.
- ADOT policy 1030: Controlled-Access Highways as Bikeways specifies exactly which freeways bicyclists are allowed to use (shoulder only).
- More about ASHTO and MUTCD standards for designated Bike Lanes.
- See comment below for the correct interpretation of the word ‘or’ in ‘as close as practicable to the right-hand curb or edge of the roadway”; which appear, e.g. in Arizona AFRAP rule (28-815A); and also appears in the required position for right turns law 28-751A and a variation in the generic slow-moving vehicle rule 28-721B.
- The terms ‘street’ and ‘highway’ are synonymous in Arizona law, see definitions here.
- Edge lines are specified in sections 3B06 and 7 of the MUTCD. Edge lines are sometimes/frequently mis-used by traffic engineers on urban streets to create “fake bike lanes”.
- Diagonal crosshatch markings (see Warner Rd photo, above, are specified in sections 3B24 of the MUTCD… “diagonal crosshatch markings may be used to discourage travel on certain paved areas, such as shoulders…”
- There is one oblique reference to driving on shoulders: §28-942 “If a motor vehicle is operated on a roadway or shoulder…”