Diverging diamond interchange opens at Elmhurst Road and I-90
Drivers on Elmhurst Road at the Jane Addams Tollway (I-90) Friday took a brief detour to England, switching over to the left side of the road as a new diverging diamond interchange went live.
The counterintuitive design channels drivers briefly to the left lanes and is one of only three such configurations in Illinois. The project that includes rebuilding and constructing new ramps accessing I-90 cost $54 million.
"I'm going to stand here and be nervous," project engineer Hope Garrett said at 9:50 a.m. as construction workers laid down final striping at the Des Plaines site.
Shortly after 10 a.m., tollway crews grinned and snapped photos as traffic signals were activated and the first contingent of cars and trucks passed through.
Essentially, "northbound and southbound vehicles take turns crossing the intersection," Garrett explained. "They'll cross over to the other side, which makes all ramp movements unrestricted. There's no opposing traffic when turning onto I-90 ramps, which means unopposed left turns and unopposed right turns."
Aside from a glitch where a few northbound drivers failed to stop for a red light, motorists took the novel configuration in stride.
"I hear it's supposed to save a lot of time," said Mike Wilkin, who works nearby in Mount Prospect. "We'll see how it works."
Tollway Executive Director Greg Bedalov said the improvement "will mean smoother traffic flow and reduce congestion in that we're eliminating one phase of the traffic signal."
The interchange is restricted to one lane in each direction over the weekend as engineers monitor the new technology and traffic flow.
On Monday, it will switch to two lanes, and two rebuilt I-90 ramps carrying vehicles to and from the east will reopen. Those ramps will handle about 21,000 vehicles daily.
On Tuesday, two new ramps taking traffic to and from the west will debut, accommodating an estimated 12,000 vehicles a day.
"It's a bit of a nuisance I have to go all the way around to get to the highway," commuter George Boykov of Schiller Park said. "But I'm sure it's going to be great when it's all done."
Underneath the diverging diamond is a tangle of utility pipes that carry liquids ranging from jet fuel to O'Hare International Airport to drinking water for suburban communities.
"That is one of the reasons we didn't deliver it in 2015; it was primarily due to utility relocation," Bedalov said.
The interchange, which includes pedestrian islands, is safer for pedestrians and cyclists, Garrett said "It's a lot easier to cross because they'll be protected with stoplights and channelized up the middle to be out of the way of ramp movements."
Drivers will need to have I-PASS transponders or pay online as the interchange is electronic. Tolls on the ramps to and from the west cost 55 cents for I-PASS users and $1.10 if you pay in cash.
Although it connects to I-90, the interchange is part of another related project -- I-490, a ring road around O'Hare. The diverging diamond will eventually service an interchange with I-490 and I-90.
Other diverging diamond interchanges are located at Route 59 and I-88 and at downstate Marion.