Drivers on the Jane Addams Memorial Tollway have been getting stuck in traffic for years. It’s a section of highway that starts at O’Hare Airport and stretches through Schaumburg and up to the Wisconsin border. A Curious City listener (who asked us not to use her name for privacy reasons) was stuck in bumper-to-bumper traffic a few months ago when she noticed construction crews installing dozens of huge metal archways and signs above the road. She was curious about their purpose, so she wrote in to ask:

What are all those archways being erected on I-90 from Chicago to Rockford?

It turns out these metal structures are part of a new initiative by the Illinois Tollway to build a “smart road.” Greg Bedalov, the state agency’s executive director, says the archways are placed every half mile on the Jane Addams from O’Hare to Barrington Road with dynamic signs that display suggestions for drivers.

For example, if there is an accident two miles down the road from driver, a sign over that lane may show a big red X, encouraging drivers to change lanes before they get to the problem spot. Another lane may show a green arrow, communicating to drivers that they should drive in that lane. Tollway engineers will remotely update the electric signs to reflect current conditions. The technology will also allow Pace buses to ride on the shoulders, much like they already do on the Stevenson Expressway in Chicago.

The smart road signs, which are expected to go live in spring of 2017, are the most visible element of a massive $2.5 billion project to replace, expand and update the entire tollway for the first time since original construction in 1958. The smart road technology accounts for $33 million of that $2.5 billion rebuild, which was funded by the independent Tollway Authority.

Representatives of the Illinois Tollway say they hope smart road technology will accomplish three goals: improve safety, reduce congestion, and develop an infrastructure for future technologies like driverless cars. How will this work in practice? We’ll look to other cities who’ve experimented with similar initiatives and talk with traffic control experts to find out.

Goal Number One: Improve Safety

There are very few places in the U.S. that have implemented the same kind of smart road technology currently being installed on the Jane Addams. The first such system was installed in Seattle, Washington in 2010. One of the main goals in Seattle was improved safety. The verdict? The system (known as “active traffic management”) really did make the roads safer. Weekday collisions were reduced by up to seven percent, and weekend collisions went down by as much as 20 percent.

Morgan Balogh, an engineer with the Washington State Department of Transportation (WSDOT), guesses there was a steeper drop in weekend collisions compared to weekday ones because weekend commuters aren’t as likely to be familiar with traffic patterns on the road and are more inclined to trust and follow the smart road’s suggestions.

Balogh’s hunch reveals a truth about the system: the system is only as powerful as the people who choose to follow the signs’ suggestions. It should be noted that following the signs is voluntary. Bedalov says the Illinois State Police will not ticket drivers for ignoring the signs unless they do something explicitly illegal, like pass traffic on a shoulder.

“The system works best when people follow the posted speed limit, maintain the proper gaps. We always encourage that,” says Bedalov. “We’re absolutely convinced that there will be a learning curve like anything else. This is a new road for us.”

Goal Number Two: Decrease Traffic Congestion

One of the Illinois Tollway’s big goals for the system is to reduce the congested traffic that’s plagued the Tollway for years. But the new smart road might not actually help reach that goal.

After the system was launched in Seattle, more drivers began using the roads and commute times actually went slightly up. Shorter commute times was not a goal in Seattle, and unlike in Seattle, the update in Illinois will include adding additional lanes to the highway.

But Matt Turner, an economist at Brown University, doesn’t think we should expect different results here. He doesn’t think that smart road technology or lane expansion will help with traffic congestion. In a study for the National Bureau of Economic research, he found that road expansion projects since 1983 have created a cascading effect — when highways increase capacity, more people drive on them, which leads to stores and housing popping up near the highway, and eventually causes more traffic.

“Traffic increases in proportion to capacity increases on the road. So if you double the capacity of the road, we observe that traffic doubles in less than five years,” Turner says. He views smart road technology as nothing more than a capacity increase, and that the seemingly positive effects of capacity increases are temporary.

Turner says when you’re making these kinds of investments, “Five years shouldn’t be the planning horizon.”

Bedalov of the Illinois Tollway is certainly familiar with the kind of research Turner conducted, but says smart highway technology is better than nothing.

“It’s absolutely an improvement over what has been traditionally available to the motoring public,” Bedalov says.

Goal Number Three: Prepare for driverless cars?

The most visible feature of the Jane Addams’ new Smart Road may be the overhead signs our questioner observed, but there’s a labyrinth of technology buried underneath the roadway — 520 miles of conduit for fiber optic cable and 132 traffic sensors. This buried infrastructure will help manage traffic. But it’s also the beginning of what Tollway representatives say they’ll need to achieve their third big goal of the expansion project: communicate with driverless cars.

“We don’t want to go out there and rip up the road again to put in new technology once autonomous vehicles or connected vehicles are here,” Bedalov says. He believes that driverless car technology is only a few years ahead of us.

Driverless cars are a “great way to overcome congestion,” Bedalov says.

Consider, for example, how often traffic problems are caused by drivers making poor decisions. “You hit a slowdown and there’s an accident, and you get past the accident, and everybody speeds up all of a sudden. Then people speed up too quickly and you’ve got to slow down again,” he says.

Bedalov says driverless cars have the potential to coordinate speeds and stagger cars in ways humans can’t. He says that the Tollway is already experimenting with driverless maintenance vehicles. But Turner, the economist, is more skeptical. He says engineers often over-promise what technology, like smart roads and driverless cars, can actually accomplish.

“The engineers have had years to solve these problems and maybe it’s time to give social scientists a shot at the problem,” says Turner.

So, until driverless cars become ubiquitous in future Chicago, Turner suggests we may need to just think more about how we drive. That’s something that even the engineers realize at the end of the day.

“Human nature is always involved in driving,” Bedalov says.

The Illinois Tollway says drivers can look out for those green arrows and red Xs overhead this August.

Special thanks to Lili Du of the Illinois Institute of Technology and Joe Schwieterman of DePaul University for research on driverless cars.

Julian Hayda is a Chicago-based international reporter and filmmaker. Follow him @JulianHayda.

An earlier version of this story incorrectly said that weekday collisions went down by as much as 20 percent. Weekend collisions went down by as much as 20 percent. This version has been corrected.

