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American Sharrow Inventor: “I Was Always Under Pressure to Do Less”

Sharrows, what are they good for? A recent study suggests that one thing shared lane markings don't do is improve safety for cyclists. The conclusion has sparked an online debate and some detailed defense of sharrows in the right conditions.

The original sharrow, developed by a Denver bike planning in the early 1990s. Image: The Bicycle Story
The original American sharrow, developed in Denver in the early 1990s. Image: The Bicycle Story

Seattle-based journalist Josh Cohen produces the Bicycle Story podcast, and in his new episode he digs into some of the history of sharrows in America. It's illuminating stuff.

Cohen interviewed traffic engineer James Mackay, who pioneered the use of sharrows in America when he worked for the city of Denver's bike program in the early 1990s. Mackay said the agency culture -- one that resisted taking any risks to improve conditions for cycling -- was a factor in the design:

I thought at that time of a sign to define that bicyclists were intended users of the road and define lane position and to confirm that jurisdictional agencies understood that bicyclists would be using the road there. We came up with a design that had the bicycle symbol, the bicyclists with the wheels, inside an arrow outline and it was quickly called the bike in the house with the man jumping barrels at home.

Part of it was the city of Denver's reluctance to do much of anything for bicycles. So I figured, this would be a less expensive approach versus the conventional bike lane markings. A lot of the agencies don't want to do anything involving change or spending money for bicycles. I was always under pressure to do less as the Denver bicycle planner.

He told Cohen that he even had to fight with city officials to implement sharrows properly:

You really need them about 150 feet apart so when you're on one, you can see the next. And 180 feet was basically the limit you can see as a cyclists for this next arrow for your lane position. Of course the first thing I get is 'Well, can you make them 200 feet apart so we have to use less of them?' That's just been the story of my career.

I was hoping the shared lane marking would legitimize the presence of bicyclists, reinforce the correct direction of travel and assign lane position, including the correct approach to an intersection and fill an intermediate niche where typical bike lane markings might not necessarily fit.

But I was hoping it overall would provide a step in the right direction towards legitimizing the presence of bicycling and reinforcing bicycle usage.

According to Cohen, in the late 1990s, other cities like Cambridge and Chicago started adopting shared lane markings. An early study in Gainsville, Florida, showed that they led more people to bike in the direction of traffic and stay off the sidewalk.

Mackay said that getting sharrows into the Manual on Uniform Traffic Control Devices, the highly influential book of street engineering standards, was "a huge process" and faced "immense pushback," finally concluding in 2005.

"What really clinched getting it in the manual was showing how different cities were using different shared lane markings," he told Cohen. "For those guys [the NCUTCD], the lack of uniformity was more frightening than doing nothing."

Cohen says the introduction of sharrows to one the nation's key engineering manuals coincided with a period in which cities were very interested in expanding bike infrastructure. So sharrows were widely installed.

But the way sharrows tend to be used isn't great for biking. Noah Budnick, formerly of New York City's Transportation Alternatives and the San Francisco Bicycle Coalition, told Cohen sharrows give politicians an easy way to say they're doing something for bicycling without making any hard decisions to reallocate street space from cars to bikes.

"In the '80s or '90s when it was a much more committed group of cyclists, this is a broad generalization, but those were the type of people who would ride whether or not there was a bike lane," he said. "As the population of people riding bikes has grown tremendously in terms of age, gender, and ability, figuring out how to best use all the different design tools is becoming more important."

The whole podcast is well worth your time.

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