Smart Road Opens Path to Next-Generation Trans­porta­tion

Under its Move Illinois capital program, the Illinois Tollway Authority (the Tollway) committed $2.5 billion to rebuild and widen 62 miles of the Jane Addams Memorial Tollway, which serves nearly 1 million travelers per day and connects the Chicago area to O’Hare Inter­na­tional Airport and downtown. Part of Interstate-90 (I-90), the Jane Addams Memorial Tollway was built in the 1950s and required a dramatic overhaul to increase capacity and ease congestion.

The Tollway set a vision to rebuild it as a 21st century corridor. This vision included turning the 16 miles of I-90 closest to O’Hare into a “SmartRoad” that applies the latest in technology to make the road safer and more efficient for users.

Studying the Past and Present, Positioning for the Future

For six decades, CDM Smith has been the Tollway’s advisor for traffic engineering and trans­porta­tion planning, providing services comprising travel demand modeling, revenue forecasting, safety and intelligent trans­porta­tion systems (ITS).

When the Tollway began setting goals for the project, CDM Smith was tapped for advice. “The Tollway was interested in active traffic management (ATM). They asked us to research examples of ATM projects to understand how they could implement it success­fully,” said project manager Jonathon Hart, AICP. ATM is a method of commu­ni­cat­ing real-time traffic conditions, travel times, lane closures and traffic pattern changes to drivers through overhead variable message signs, traffic cameras, sensors and other tech­nolo­gies. Hart and his team researched ATM systems in both the United States and Europe, gathering data and analyzing what went right and wrong, and what could have been done differently to yield better results.

The team also completed a compre­hen­sive study of the symbols displayed by those systems—the X’s and arrows used to indicate, for example, closures, open lanes or incidents ahead on the road. Extensive field testing was performed under controlled conditions to understand how well drivers could recognize different symbols—or the combination of symbols and text—at various distances. “Though it sounds mundane, showing a slanted yellow arrow for ‘merge’ instead of a horizontal one makes a big deal,” said Hart. “It impacts reaction times and safety for all drivers.” In conjunction with the Federal Highway Admin­is­tra­tion, whose Manual on Uniform Traffic and Control Devices is the national standard for roadway signage, CDM Smith’s experts developed several new symbols to optimize message clarity for drivers.

A concept of operations was delivered to the Tollway for the ATM system and a public outreach program was developed to educate users. “The studies helped the Tollway position itself to capitalize on the experiences of others,” said Hart, “giving them the lessons learned to implement the best ATM system possible.”

Making the Road Smart

SmartRoad began operating in September 2017. Overhead gantries are placed every half mile with above-lane digital signs that can display a variety of symbols, indicating accidents, advisory speeds and lane closures, as well as transit-only and high-occupancy-vehicle service when applicable.

Courtesy of the Illinois Tollway Authority

In addition to these signs, SmartRoad uses sensors to collect data that is shared with popular mobile navigation apps to help drivers plan their trips. This data also informs messages the Tollway can show on dynamic message signs located on every other gantry. Additionally, new high-definition cameras allow Tollway operations staff to monitor SmartRoad 24/7. Meanwhile, wireless weather stations monitor pavement and weather conditions at critical locations, including bridges, and feed that information back to drivers.

Finally, the inside shoulders of I-90 are designed to function as “Flex Lanes,” which provide the Tollway flexibility in options, both now and in the future. Using the ATM system, the Flex Lanes can serve as anything from a transit lane, to additional capacity, to a managed lane with minimal effort and without requiring new construction. Today, the Flex Lanes are used by Pace suburban buses to help ensure reliable travel times for transit service when the highway is congested. The Flex Lanes can also be leveraged by emergency vehicles if an accident occurs or to route traffic around an incident without loss of capacity.

A Link to the Future

The safety and mobility upside the ATM system enables is evident, yet CDM Smith senior ITS engineer Jeff Hochmuth, PE, PTOE, views another component of the project as equally, if not more, important: “We advocated that the Tollway should put down fiber optics, power utilities and concrete footings in the road to provide additional flexibility for emerging tech­nolo­gies and alternative operations.”

Now in place, this infra­struc­ture will allow the Tollway to install equipment required by future connected and autonomous vehicle protocols at frequent intervals along the road. The flexibility afforded by it means SmartRoad can evolve alongside industry advance­ments and that the Tollway can consis­tently improve service.

“It was good forethought,” said Hochmuth. “We knew the opportunity to rip up I-90 and put it back down wasn’t going to come along again soon. So how could we prepare the road for the next 30 years?”

“When we began helping the Tollway craft its vision,” said Hart, “terms like ‘connected vehicles’ and ‘autonomous vehicles’ had not entered the public lexicon. We were really trying to look into the future with this project. The possi­bil­i­ties opened by the power and fiber are immense. I-90 now is really a link to the future of trans­porta­tion design and operations.”