Below for illustration is 4 different lane treatments commonly used on urban arterial roads — these all just so happen to be the same road, Chandler Blvd, in the City of Phoenix:
- multiple, narrow lanes; directly next to curb and gutter
- wide outside lane, the rightmost through lane. The lane to the right of the solid white line is a right-turn-only (this is a brief ~ 1/2 mile stretch — wide lanes are unusual on arterial roads);
- multiple, narrow lanes; with edge line and small shoulder next to curb and gutter
- multiple, narrow lanes; next to a designated bike lane
For our purposes here, “narrow” refers to “too narrow for a bicycle and a vehicle to travel safely side by side within the lane”, and “wide” means it is wide enough to safely share side by side. In the areas in the picture, the narrow lanes are all approximately 11′; the wide lane is perhaps 15′.
When the lane is “wide”, as in photo 2, bicyclists in the presence of faster traffic must right as far right as practicable, unless some other exception exists. When the lane is “narrow”, as in photos 1, 3, and 4, bicyclists need not ride in any particular position because the bicyclist’s AFRAP (As Far Right As Practicable; also sometimes referred to as FTR Far To the Right), §28-815A is, by definition, excepted. Faster drivers must overtake using the next lane, waiting as necessary for safety. There is no time limit.
Exactly how many wide lanes are there?
I inquired of our city streets dept exactly how many arterial roads are there, and how many of them have wide outside / wide curb (let’s say 14′ or wider) lanes? As things turn out, the city has 735 centerline miles of arterial streets. All are laned for traffic (that’s probably obvious), but it’s not easily knowable exactly how many have wide lanes; though i was told “few”. In my experience, it is well under 10%. So there you have it: in the city of Phoenix, the vast majority of arterial roads have lanes that are “too narrow to safely share side by side”. I mentioned, above, a brief ~ 1/2mile stretch of Chandler Blvd that is wide, and is the only wide arterial road anywhere in my section of the city (Ahwatukee); another example elsewhere in Phoenix is Bethany Home Rd between 12th and 16th St.
Here are the figures for centeline-mile of streets in the City: 283 miles of Major Arterial roads, 452 miles of Arterial roads (equals 735 miles of arterials), 134 miles of Collector streets , 478 miles of Minor Collector streets. 3,509 miles of Local streets; grand total 4,856 total miles of streets in the city of Phoenix.
Sample wide lane / Sample unlaned
As a practical matter — bicyclists are rarely required to ride “as far right as practicable”; because of exceptions in the law, 28-815A.
Incongruously, many more collector streets have wide lanes. This leads to what many would consider a counter-intuitive result that bicyclists riding on the vast majority of “busy” arterial streets, need not (and usually should not!) keep to the right; whereas on many (far less trafficed) collector streets, bicyclists must ride to the right (unless some other exception applies).
Sample collector road: Ranch Circle North ; has 1 wide lane (15′ plus) and one nominal sized bike lane in direction. Note that because the travel lane is “wide” a bicyclist is, in effect, required to use the bike lane in the presence of overtaking traffic (unless another exemption exists). This is a relatively unusual geometric situation. I have to check the speed limit, I believe it’s posted 35mph?
Sample residential / local street; unlaned, and very wide (maybe 40′) — 1000 N block McKemy Ave, City of Chandler, Arizona. Very low traffic volumes, posted (and statutory) speed limit is 25mph. Some local streets are laned, and some are not. Local streets are the only type of urban road you are likely to find without marked lanes, anywhere in the United States. A bicyclist in the presence of overtaking traffic is required to ride as close as practicable to the right curb (unless another exemption exists). If the bicyclist was traveling near the statutory speed limit; the requirement would vanish.