Tollway's 'mother ship' chews up concrete, spits out savings on I-90
Inching along on the Jane Addams Tollway in construction land, two questions arise.
Which movie dystopia is the dusty landscape dotted with hills of rubble more reminiscent of - the gritty highways of "Mad Max" or the decimated District 13 in "The Hunger Games?" And what are those piles of rock for, anyway?
The first question is a matter of opinion, but here's the answer to the second.
The massive widening and rebuild of the Jane Addams (I-90) is winding up this year. And in a sense, the road is building itself.
"Our efforts are focused on minimizing the environmental impacts associated with our road building," tollway Chief Engineer Paul Kovacs said.
That means recycling and reusing the existing concrete and asphalt as a base material for the new road bed with the help of some nifty equipment.
The star of the show is the "mother ship," or mobile crusher, a huge and ungainly machine.
"It's a unique and fantastic way of keeping the existing materials on site and turning them into the proper size so they can be reused again," Kovacs said.
The tollway builds its roads with concrete and uses asphalt for shoulders and resurfacing. Workers start by breaking up the existing pavement into large chunks. The material then is mounded separately in the rows familiar to I-90 drivers.
Enter the mother ship.
Mile by mile as the roadwork moves east, a backhoe loads the pieces of concrete into the mobile crusher's feeder. They're pulverized into 4-by-6-inch chunks and whisked onto a conveyor belt that spits the finished product onto the road bed, making for a solid base.
A layer of recycled, ground-up asphalt follows later, then three inches of warm asphalt.
"After we have a stabilized base, we build a new concrete layer on top to create this ... sandwich," Kovacs said. "The new concrete pavement is typically 13 inches thick."
The tollway tailors the depth of concrete to the type of traffic, adding the thickest layer where truck traffic is heaviest, such as on the Central Tri-State Tollway.
The agency has used its I-90 rebuild as a laboratory to test mixing old asphalt shingles and pavement with new.
As a result, recycled asphalt comprises about one-third of the new asphalt laid on the mainline and about 50 percent of material used for the shoulder.
"It's environmentally a very good approach to road-building and it also has a very important component of saving us a lot of money," Kovacs said, adding the agency has saved about $200 million since 2006 by recycling and reusing.
"We don't have to buy the new materials, we don't have to haul in new materials and remove old materials, and we don't have to pay any (landfill) disposal fees."
<h3 class="leadin">One more thing
The final stretch of the Jane Addams revamp should wrap up at the end of the year. The I-90 project, costing $2.5 billion, is part of the agency's $12 billion, 15-year building program.
<h3 class="leadin">You should know
It's coming up to Week 7 of the O'Hare overnight runway rotation aimed at distributing jet noise more evenly around the region when folks should be sleeping. So far, so good, says Bensenville Mayor Frank Soto. The village next to O'Hare has suffered significantly since Chicago shifted to a new east/west flight pattern.
Using different runways from 11 p.m. to 5 a.m. or so has decreased the pain somewhat, Soto said. Emails from residents include comments such as, "this is the eighth time I haven't had planes over my house all night long."
http://reportcards.dailyherald.com/gfx/2016/rotation/This week's lineup should affect folks in Wood Dale and Bensenville for arrivals and in Chicago with departures.
<h3 class="leadin">Upcoming
The DuPage Railroad Safety Council is always on the forefront of train issues. It holds a Prevent Tragedy on the Tracks forum from 8 a.m. to 4:30 p.m. Sept. 15, at the Drake Hotel, Oak Brook.
The focus is on eliminating trespasser deaths and injuries. To learn more, go to http://www.dupagerailsafety.org/index.html.
<h3 class="leadin">Gridlock alert
So much to share.
• IDOT will close lanes and road shoulders on Meacham Road north of Salt Creek in Rolling Meadows and Schaumburg Monday for drainage repairs. Work should wrap up in September.
• Expect lane closures on Route 83 starting Aug. 22 in between Emmerson Avenue and Busse Road in Itasca and Wood Dale for an IDOT resurfacing project. The fun lasts until fall.
<h3 class="leadin">Risky business
Women take fewer risks at street-level CTA train crossings, a study by the University of Illinois at Chicago's Urban Transportation Center shows. Students analyzed data from pedestrians and cyclists and found that men age 21 and younger are more likely to ignore warning signals and proceed across the tracks. The report also found that people 51 and older respond better to active warning devices as opposed to signs.