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
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, 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.