Pay attention when Route 59, I-88 interchange opens Monday
Motorists are being urged to stay alert while traveling along the new diverging diamond interchange when it opens Monday at Route 59 and I-88 in Naperville.
"We want the public to know that this interchange might seem a little different at first, but we expect the transition to be a smooth one," said John Fortmann, region 1 engineer for the Illinois Department of Transportation.
Officials explained the benefits of the new interchange during a news conference Friday on the 12th floor of the Hotel Arista in Naperville. The location gave attendees a bird's eye-view of the $90 million project.
The design features two new bridges that cross over I-88. The western bridge is for northbound Route 59 traffic, while the eastern bridge is for southbound traffic.
Prior to the start of the project, there were 10 "crossing conflict points," or points where two vehicles could meet at the same time. The new design decreases the number of conflict points to two. Those points are on the north and south ends of the bridges, where the northbound and southbound lanes crisscross at signalized intersections.
Engineers say the crisscross essentially routes traffic to the opposite side of the road for several hundred feet, to eliminate the need for motorists to turn left onto ramps in front of oncoming traffic.
"The best advice we can give motorists at this point is to pay close attention the first few times you traverse the interchange," said Steve Travia, engineer of operations for IDOT. "There will be new signage, different signals, new markings. It may be a little unusual at first, but everything we've heard is that the transition from a traditional diamond interchange to a diverging diamond interchange is relatively seamless and well-received by users."
The diverging diamond is modeled off similar exchanges in other states, including Missouri, where interchange area crashes were reduced by 53 percent in the first year diverging diamonds were used. Officials added that the crisscross forces traffic to reduce speeds as it crosses over the bridges, and wrong-way entry onto ramps will essentially be eliminated.
Aside from improving safety and decreasing congestion in the area, the design also will increase capacity, as the number of lanes in each direction is increasing from two to three. However, when the interchange opens prior to the morning rush Monday, only two lanes will be accessible in each direction. The third lanes are expected to open on Oct. 16.
The entire project is expected to be complete by early to mid-November. It encompasses three miles of Route 59, from Ferry Road south to Aurora Avenue/New York Street. Officials said the stretch from Ferry Road south to North Aurora Road should be done by mid-October.
Bill Wiet, director of development for Aurora, said if the project stays on track, its completion should be "a fantastic Christmas gift" for shoppers hoping to visit the retail areas on Route 59 during the holiday season.
Paul Kovacs, chief of engineering for the Illinois Tollway, also thanked motorists for their patience and commended the engineers and construction workers who have been working on the project for the past two years.
Officials said they selected the Route 59 intersection as the first to have the diverging diamond design in the Chicago area because of its heavy volume of traffic, especially left-turning traffic. Roughly 180,000 vehicles travel through the area every day, including 50,000 vehicles on Route 59.
This is the second diverging diamond interchange in the state. The first opened earlier this summer in downstate Marion and a third is being built at I-90 and Elmhurst Road interchange. Design for another diverging diamond at I-55 and Weber Road near Romeoville is also underway.