As Seen on the Tollway: Lights of Different Heights


Cruising along the Jane Addams Memorial Tollway (I-90) at night, it’s impossible to miss the brilliant LED lights that illuminate the road to make driving safe and easy.
What’s less noticeable to drivers as they pass the evenly spaced light poles—all set about 75 yards apart—is that not all of the poles are the same height.
While virtually all of the light poles in the center median between Elgin and Rockford stand 50 feet tall—two in rural Boone County are dramatically shorter.
One light pole is 30 feet tall, while the one next to it is 20 feet high. 
Why the miniature light poles?
It turns out the poles are in the flight path of United Acres Airport, a small grass airfield located off Spring Center Road that is angled so planes landing and taking off there cross I-90 at low altitude.
When the Illinois Tollway started drafting plans for widening and reconstructing I-90 between Rockford and Elgin—a project that began in 2012 and included adding new LED lighting along the road—designers realized they would have to accommodate the flight path of the single-runway, privately-owned airfield recognized by the Federal Aviation Administration.
To provide the FAA-required safety clearance for the small aircraft using the airfield, the Tollway design team lowered the height of the two light poles near the end of the runway to ensure they would not interfere with the airfield’s flight path. Lowering the light poles protect pilots using the airfield while still providing drivers with the light they need to travel safely.
A sharp-eyed driver recently noticed the difference, prompting Rockford TV station WTVO to run this story
While shorter light poles are rare along the 294-mile Tollway system, they’re not just confined to rural Boone County.
Several light poles along I-90 near Lee Street in Cook County are shorter for the same reason—to keep them out of the flight path of a runway at the better known, exponentially busier O’Hare International Airport. 
“These are definitely unusual situations, but we’re always willing to make changes along our system that will enhance safety, not just for our customers but for everybody who lives or works near our roads—or flies over them,” said Illinois Tollway Executive Director José Alvarez. 
On several other toll roads, including the Veterans Memorial Tollway (I-355) near North Avenue, and at several other locations along I-90, light poles in the median stand noticeably lower than other nearby poles.
The reason for the shorter light poles again is safety—not for pilots, but to provide a safe margin for overhead electrical transmission lines that cross the roadways at those locations.