A three-block stretch of Argyle Street in Uptown has been turned into a "shared street." As Chicago previewed last year, the concept gives pedestrians the right-of-way throughout the street, eliminates curbs, and minimizes street markings, replacing them with differently colored paving stones. Car, bike, and pedestrian traffic is mixed rather than segregated.

But according to reports from Streetsblog and the Tribune, the execution is confusing people.

This is in part because it's not complete, and because the paving stones are the wrong color. But it's also part of the point. Shared streets are supposed to be a bit confusing, under the theory that it makes them safer—and the evidence suggests that it works. But first it helps to understand the theory.

Shared streets, or shared spaces, are a recent invention and largely the work of one man, Hans Monderman, a Dutch traffic engineer. (The Dutch are legendary for their traffic engineering.) In 2001, Monderman took a fairly typical four-way intersection in the small Dutch city of Drachten, installed a roundabout at the center, and eliminated all the traffic lights and most of the street markings. You can see a before-and-after here. Here's a video of it in action:

Drivers, cyclists, and pedestrians have to work it out for themselves, rather than fobbing off their attentiveness on lights and letting the built environment do the work. Drivers slow down; the cyclists—helmetless!—tend to signal their intentions.

It's downright un-American.

By contrast, consider a widely derided recent op-ed in the Tribune by John McCarron about bike lanes in Evanston, in which he writes, "God forbid you should make a right turn without first checking if a biker is pedaling up behind that row of parked cars."

As Streetsblog’s John Greenfield points out, it's a rather unfortunate statement because checking for cyclists is literally the law. It's also a rather remarkable statement, given that McCarron is irritated by giving the slightest of pauses so as not to maim or kill someone. But it's indicative of a larger attitude towards driving: We feel we're safest when we have to pay the least attention to our surroundings, which is why roads are generally set up as stop/go binaries.

Monderman's idea turned that completely on its head. If there aren't rules, people have to be more cautious, which means they have to drive slower and be more observant. Shortly before his death in 2008,  he explained his philosophy to Tom Vanderbilt:

As I drove with Monderman through the northern Dutch province of Friesland several years ago, he repeatedly pointed out offending traffic signs. “Do you really think that no one would perceive there is a bridge over there?” he might ask, about a sign warning that a bridge was ahead. “Why explain it?” He would follow with a characteristic maxim: “When you treat people like idiots, they’ll behave like idiots.”

It worked. Crashes declined in the Drachten shared street. But not only that: Traffic flow improved, for cars and pedestrians alike. Not only was it safer, it was more efficient.

Monderman's idea spread throughout the world. Sweden, Germany, London, Auckland, and Seattle all built shared streets, and saw benefits—lower speeds, fewer crashes, more cycling, higher property values. Even Normal, Illinois, built a Drachten-like shared roundabout, which was one of the subjects of a shared-streets study that found Drachten-like benefits , as documented in Public Square:

Uptown Circle, part of a new urban revitalization, features a circular park in the middle of a large traffic roundabout. The park is a popular public space. Surrounding sidewalks have full curbs, unlike the other shared space intersections. Uptown Circle featured the highest average traffic speeds—10 miles per hour—of any of the examples. The pedestrian and vehicle volume is relatively low—280 pedestrians and 81 vehicles per hour—compared to the other examples. The pedestrian delay at Uptown Circle is less than a half second, while the vehicle delay is 4 seconds. A signalized intersection at this site would have a predicted delay of 15 seconds.

So shared streets tend to be safer yet more efficient. What's not to like?

A couple years after Monderman's roundabout was installed in Drachten, researchers found out. Respondents to a survey noticed, and approved of, the improved traffic flow; those rating it "bad" fell from 67 percent to 6 percent, and those rating it good rose from three percent to 50 percent. Those rating the quality of the public space bad fell from 49 percent to 6 percent, and rating it good rose from 6 percent to 61 percent. Perception of "social safety" improved as well.

But perception of traffic safety—despite the fact that it was actually safer—declined. Those rating it good, reasonable or moderate fell; those rating it bad rose from 12 to 20 percent.

That mirrors findings in England, where a member of the House of Lords (and a blind former Paraolympian) commissioned a study that found 63 percent rated their experience with shared streets "poor." Eighty percent of respondents in a study of a shared road in Ashford, England, "felt safer under the previous road layout," even though the design was so successful that Jeremy Clarkson of all people—the crass former host of the speed-worshipping car show Top Gear—ate crow and admitted that his predictions of carnage and death were wrong.

Vanderbilt asked Monderman about the declining perceptions of safety in Drachten. And Monderman said something very interesting: "This was music to Monderman’s ears. If they had not felt less secure, he said, he 'would have changed it immediately.'"

The idea of shared streets is completely counterintuitive: You replace a false sense of safety that makes things riskier with a false sense of risk that makes things safer. It works without seeming like it's working.

But this paradox makes shared streets a difficult sell. There's pushback in the Netherlands based on the decline in subjective safety, which has led to more traditional revisions of the shared streets. A collaboration between Dutch and German engineers in 2007 reached this conclusion: "Because of the low speeds it is easier for people to react to one another and to control conflicts. The few accidents that happen are less severe. In practice this assumption appears to be correct. After reconstruction the number of (reported) injury accidents are indeed lower compared to the old situation. On the other hand, there still are noticeable conflicts, and this leads to criticisms by engaged parties, both car drivers and ‘sojourners’. They do not feel safe."

The Argyle shared street seems like it can be improved, but it'll always be a bit confusing, because that's how it's supposed to work. Whether Chicagoans can work with that remains to be seen.