14 foot lanes

There has been a discussion on the Association for Pedestrian and Bicyclist Professionals (APBP) listserv for the last two weeks on what to do with an outside lane of 14 feet (without on-street parking), particularly when there is a seam between the asphalt pavement and the gutter pan. Several people encouraged the use of narrow, substandard bike lanes in an effort to get something on the street, rather than using sharrows in the wide lane, or just leaving the lane unmarked. I believe we need to be very careful to not create “bike lanes at any cost,” and to carefully consider the actual roadway conditions before specifying anything that does not meet or exceed standards. The diagrams below are from the NACTO Urban Bikeway Design Guide. The first shows a high quality bike lane adjacent to a curb; the second one shows sharrows rather than a bike lane where there is not sufficient roadways width.

bike lane adjacent to curb (right side): NACTO Urban Bikeway Design Guide

bike lane adjacent to curb (right side): NACTO Urban Bikeway Design Guide

shared lane markings adjacent to curb (left side); NACTO Urban Bikeway Design Guide

shared lane markings adjacent to curb (left side); NACTO Urban Bikeway Design Guide

I am not free to share other people’s comments on the list, but I can share my own, below:


Wow. What I initially took to be inattention to the details of pavement condition in bike lanes turns out to be justification for substandard bike lanes. This really concerns me, particularly from people that I usually consider to be leading progressive voices. My perspective on this comes from my experience as a largely vehicular bicyclist in the place in which I live, and being the lead instructor for the majority of TS101 courses in my region and assistant in many LCI seminars. I live and teach in California, but am familiar with bike facilities in other western states.

The faux bike lanes mentioned by Peter as “undesignated lanes” are epidemic in the county in which I live (Sacramento). They include sudden narrowing without warning, seams between pavement and gutter and previous overlays, deep ditches immediately adjacent to the shoulder, rough utility covers, failed utility patches, and of course the ever-present debris. It is technically illegal to use shoulders as travel ways, though unlikely to be enforced. I don’t use these shoulders, yet motor vehicle drivers don’t realize that they are not legal bike lanes nor understand the legitimate reasons for not riding in them, so they continually harass me and other bicyclists for not using them. This is no accident on the part of transportation engineers in the county – they prefer marginalization of bicyclists to responsible roadway design. The cities within the county, which are more progressive than the county, have removed many but not all of these faux bike lanes.

In the League of American Bicyclists Traffic Skills 101 course, instructors are pretty agnostic about bike lanes, but do teach in detail about how to recognize and respond appropriately to bike facility conditions. In all states there are exceptions to the “far to the right” requirements, varying by state from Oregon which recognizes almost no exceptions to other states which are quite liberal on exceptions. One of the conditions which makes bike lanes unsafe is linear features which may force the bicycle to behave in undesired and unexpected ways. The seam between gutter and pavement is a linear feature, whether it is the result of deterioration that Craig Williams points out or repaving/overlay that I pointed out. Of course if nothing unexpected happens, a bicyclist can ride successfully on one portion or the other, gutter or pavement. But “nothing unexpected” is not the real world, and certainly not a design criteria for safe bike facilities. The unexpected does happen, and the bike lane needs to be wide enough to accommodate this without subjecting the user to unsafe and potentially fatal consequences. Three feet outside the gutter does not qualify.

I believe it is a mistake to squeeze in substandard bike lanes just to have something on the ground. I call this “bike lanes at any cost.” If a good facility cannot be put in, then there should not be a facility at all. I realize that some inexperienced bicyclists feel safer in a dangerous bike lane than they do taking the lane, as a vehicular bicyclist, but I know of no one who has been through a TS101 course who feels this way. I am in fact cognizant of the needs of less experienced bicyclists, and feel that anything we install should not only feel safe but actually BE safe. This is not a situation in which the perfect is the enemy of the good. Substandard bike facilities are the enemy of all.

I am not a vehicular bicyclist who is opposed to all bike facilities (this is largely a category imagined by others, anyway), but I do believe very strongly, as a user and educator, that bike facilities need to be done right.

At some odds with NACTO and complete odds with AASHTO, a safe bike lane is:

  • adjacent to curbs, 4 feet minimum of pavement without seams, either fully asphalt pavement or fully gutter pan
  • adjacent to parked cars, 6 feet minimum of pavement without seams or other hazards

I have pointed out to a number of transportation engineers that they could solve this curb bike lane issue by either running the asphalt to the curb or by constructing wide gutter pans. On the pavement to the curb idea, they respond that this is not possible, that it would lead to all sorts of drainage and maintenance issues (despite the fact that this is standard in many parts of the country, without major issues) or “that isn’t the way we do things here,” meaning that the standards which I blindly follow specify something different. Constructing wide gutters is more expensive, as concrete is more expensive, and requires a higher level of construction expertise, than asphalt. Nevertheless, these are solutions to consider.

And 2015-02-03:

I agree that the dimensions of the adjacent lane are critical, but it is really the entire cross-section. Transit providers are usually not the agencies fighting narrower lanes, it is fire departments who routinely purchase trucks that are as wide as legally permitted. Transit agencies are pretty good about training their drivers to react to the road and traffic conditions in front of them, not some ideal, and increasingly, to be respectful of vulnerable users and bike lanes. (My point is not that they are perfect, but that they are good and getting better.)

Most buses (in the US) are 102 inches (8 feet 6 inches) body width. In California the maximum width, including mirrors, is 108 inches (9 feet). Modern buses have mirrors mounted higher than the bicyclist’s head, though that is not true of older buses. Unfortunately, fire trucks have a maximum width of 120 inches (10 feet) in California, which in my opinion is not safe for anyone.

If there is one lane each direction with a center turn lane, the bus or any other large vehicle (or a driver complying with the three foot passing rule) has wiggle room to work with, and so narrower lanes of 9 to 11 feet are not a problem. Another argument in support of road diets! On the other hand, if there is a narrow travel lane adjacent to the one being considered, or a median that continues for a distance, the vehicle driver may not have wiggle room, and that must be addressed. It has been argued by others that 10 feet should be the default, with other lane widths used as needed and justified. I’m in agreement.

Join the conversation! 1 Comment

  1. hi Dan,
    on the topic of: I believe we need to be very careful to not create “bike lanes at any cost,”…
    That is a recurring theme http://azbikelaw.org/blog/shoehorn-bike-lanes/

Comments are closed.

About Dan Allison

Dan Allison is a Safe Routes to School Coordinator in the Sacramento area. Dan dances and backpacks, as much as possible.




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