Which Bike Lanes Should Be Protected? New Guide Offers Specifics

Boston, Massachusetts.
Boston, Massachusetts.

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Say this for conventional bike lanes: they’re easy. Building protected bike lanes takes real work.

Maybe that’s why, since U.S. cities started building modern protected bike lanes 10 years ago, one seemingly simple question has come up more than maybe any other: Which streets need them?

It’s impossible to answer that question perfectly, and most U.S. road design institutions haven’t tried. Until now.

At its annual conference Tuesday in Chicago, the National Association of City Transportation Officials released a free 16-page document that makes one of the first comprehensive attempts to answer that question.

In advance of NACTO’s full digital rollout (coming in a couple of weeks), we’ve got a sneak peek at the contents.

NACTO has created a formula for analyzing any street in the world

The document’s title is “Designing for All Ages & Abilities: Contextual Guidance for High-Comfort Bicycle Facilities.” Here’s the nut:

That’s a chart designed to take the basic traits any street — auto speed, traffic volume, lane count — and spit out a recommendation of what sort of bike lane the street should have to create the sort of low-stress riding experience that gets people of “all ages and abilities” — eight-year-olds, 80-year-olds, bike-sharing tourists — on bikes.

Got a two-lane, two-way 25 mph street that carries 4,000 autos per day? According to NACTO, a buffered bike lane will do. But if the traffic speed is 30 mph, it’s time to protect the bike lane with a curb, posts or planters.

Many city agencies have already put together their own internal guidance for questions like this, and NACTO’s guidance here is on the stringent end of the spectrum. For example, the PeopleForBikes Bicycle Network Analysis considers a conventional striped bike lane to be “low-stress” if there’s no curbside parking and speeds are less than 30 mph.

NACTO, though, is holding its recommendation to a higher standard, and that’s fine. “All ages and abilities” is, after all, a higher bar for a bike lane than simply “low stress.”

One of NACTO’s key points: Traffic speed is something cities can and should control

There’s no need to find more space on a street for bike lanes when you can achieve the same benefits by slowing down cars.

That’s one of the most important ideas captured in NACTO’s guide, and it’s something U.S. cities and safety advocates are increasingly realizing they’ve often forgotten to consider.


On all facility types, reducing motor vehicle speeds to 20–25 mph is a core operational strategy for improving bicycle comfort … In addition, reducing speeds can also make it easier to enact other safety changes, such as changes to intersection geometry, signalization, turn lanes, and turn restrictions. Since operational changes do not impact what types of vehicles can use the street, they usually do not require significant planning beyond the street itself, and are often the easiest type of change to implement.

As NACTO’s guide shows, speed affects bikeway stress in subtle ways. As this cleverly simple chart shows, speed doesn’t only affect the danger of cars as they whoosh past someone biking: It also affects the number of cars that whoosh past someone biking.

And here’s an interesting chart that shows how the causes of traffic stress change with the clock. The zigzagging line shows traffic-speed-related stress, while the vertical bars show traffic-volume-related stress:

“Designing for All Ages and Abilities” suggests slowing autos with a technology most cities already know well: traffic signals. For example, quick red-to-green cycles or a “low-speed signal progression” (in other words, timing the signals so someone traveling at 15 almost always hits green lights) keep traffic flowing but make it pointless for bad drivers to jam the gas pedal between lights.

Adding green arrows or bike-specific signal phases can reduce biking stress without road space changes, too.

This document from NACTO isn’t the final word on when to build what where. No single document could be; ultimately it’s up to local professionals to decide what each situation calls for, and also what’s politically achievable.

But in a world full of uncertainty, it can be nice to have a set of specific recommendations in black and white. That’s what this document does.

24 thoughts on Which Bike Lanes Should Be Protected? New Guide Offers Specifics

  1. This obviously doesn’t do anything to get cities to actually adopt these guidelines, but planning officials and political decisionmakers are often extremely reluctant to stick their neck out on pioneering stuff like this. Hopefully, the fact that they can say they were following a respected authority’s guidelines will help push things forward.

  2. What the hell is the resistance to just extending the sidewalk and making that into a bike lane? It sends a cue to drivers it’s not where they should drive. When you tally up all the death and confusion caused by doing it the way we’re doing it, I bet the sidewalk extension route isn’t even much more expensive.

  3. The problem is clear. If the bike lane is a mere extension of the sidewalk then you have the situation like in Europe, where every kid, senior, homeless person etc. sees the bike lane as part of the sidewalk, and then you cannot make any progress because of all the shopping carts, wheelchairs, skateboards, strollers etc

  4. I could see Americans behaving that way, I guess, but Europeans generally don’t. And lo and behold, more people bike and get further when they do.

  5. but make it pointless for bad drivers to jam the gas pedal between lights.

    Clearly they haven’t checked out Valencia St where that is that standard driving pattern.

  6. Direct, high-frequency bus routes travel streets signed 30mph and over. If the bike buffer is less than 8 feet deep, bus stops can’t meet ADA.

  7. The bus can pull to the curb. Furthermore, if there is no raised landing in the buffer, then the bus must pull to the curb

  8. How much money do you have? Your statement indicates you have no knowledge of the costs, engineering, etc. (regardless of the cost of deaths, which don’t come out of a city’s pocket).

    Furthermore, most cities go the quick-build route to get started, refine the design, or scrap it if it isn’t getting significant use. You can’t do that with raised infrastructure.

  9. It’s not perfectly analogous, but I do know the approximate cost to replace sidewalk in NYC. I also didn’t say there isn’t a reason to do it the way they’re doing it, but why isn’t it at least discussed? Obviously it’s not out of reach of other first world countries.

    And costs of deaths and injuries often do at least partially come out of the city’s pocket. They also affect the local economy, healthcare system, insurance rates, etc.. There is a quantifiable cost to making bike lanes more dangerous.

  10. This chart is a good idea. It sets boundaries and recognizes differences in road conditions. It needs to have another flow added to show that there are streets which should not have bike lanes added. Maybe that is implicit in the last few rows, but roads with average daily volume of 25,000-40,000 and speeds of 40-50 should not have bike lanes if it can be avoided. Better and safer to add them on parallel streets.

  11. The CROW manual is behind a paywall, so a lot of people don’t have access to it. I’d love to read it someday, but I’ll enjoy the free NACTO guides in the meantime.

  12. I agree, I like sidewalk-level bike lanes (or half-level) in many cases (there’s enough room on much of Bushwick Ave to put lanes on the sidewalk level!), but underground utilities like catch basins often get in the way and can be real expensive to move.

  13. Bob,

    Your interpretation of the conditions of the bike lane and how they are used in Europe are either made up or poorly remembered from your own experience.

    Best, Frank

  14. RichLL has regularly claimed that he hasn’t biked since he was a child, so it’s the former.

    He uses this line when any kind of protected bike lane comes up because he apparently believes that concern-trolling sounds better than complaining that he can’t double-park his car in them.

  15. RichLL just wants people to believe this is what will happen to try to discourage people from supporting protected bike lanes. He’s not above actively threatening to constantly do it himself or lying about the law to push this narrative; see his comments in this thread (as Walt, until he renames that account again):

  16. *shrug*

    Well, I don’t want to get into it with anti-bike cretins, but bike advocates in the USA often get this one wrong too, which is why I was responding.

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