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.”

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.

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.”

This week’s lineup should affect folks in Wood Dale and Bensenville for arrivals and in Chicago with departures.

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.

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.