Building Bridges Raises OHare Airport Lights to Clear a Path for the New I-490 Tollway
The Illinois Tollway is building four unusual bridges along the western edge of O’Hare International Airport that won’t carry cars, trucks or even pedestrians.
As part of its work to build the new I-490 Tollway, the Tollway is constructing the bridges to support the specialized approach lights used to help guide commercial jets to safe landings on O’Hare Airport runways.
The new I-490 Tollway will run near the edge of O’Hare Airport and its planned path will take it directly through approach lighting systems for four runways. At each runway location, a string of more than a dozen approach lights flash sequentially to direct jets during the landing process.
Building the narrow steel bridges will raise several of the approach lights for each runway above the I-490 right-of-way so the new road can be built underneath, while jets can continue to use the lights as a navigational aid to safely land at O’Hare at night or when visibility is poor. Based on its location, each bridge will hold either three or four of the light towers.
The key to building the bridges, according to Tollway engineers, is maintaining the required distance between each of the lights so incoming jets can hold the proper height and descent angle as they approach the runways.
Because the distance between the lights is critical, engineers and construction crews have to ensure that each light on the new bridges will be spaced between 90 and 105 feet apart—maintaining the same spacing required of the other lights on the ground at either end of the bridges.
The timing of the construction has been challenging, given the importance of the approach lights to daily airline operations at O’Hare.
Since all of the approach lights at the western end of each runway must be taken out of service during construction of each new bridge, the Tollway has been limited to constructing one bridge annually to limit the impact of the work on daily flights.
The first of the four new bridges is in operation at Runway 10 Left near the southern end of O’Hare after being completed last year.
Crews currently are building the second bridge at the end of Runway 9 Left, with that work scheduled to be completed this year.
The two additional bridges are scheduled to be built in 2024 and 2025.