Urban planning legend Daniel Burnham once said, “Make no little plans.” He would be proud of the Illinois Department of Transportation (IDOT), which currently is reconstructing the Dan Ryan Expressway through the heart of Chicago. The $975 million price tag on this three-year project reflects its massive undertaking.
There's really nothing easy about this project. Although IDOT is promoting alternate routes, the open lanes will continue to carry heavy traffic, complicating the logistics of moving equipment and materials needed for the job. Beyond traffic and safety issues, there is the sheer complexity of the project. For example, new lanes are being added along certain portions of the expressway, all the bridges along the route are being worked on, new retaining walls and drains are being built, and numerous ramps and approaches are being realigned. Additionally, for the first time IDOT is using ground granulated blast furnace slag as a substitute for some of the portland cement in the concrete. As huge and complex as it is, attention to the myriad of details should keep Chicago moving freely for the next 30 years.
The big picture
The Dan Ryan project runs along 10 miles of Chicago's south side, from 15th to 95th streets. Originally constructed from 1961–1963, the expressway then carried 150,000 vehicles per day. Today traffic has ballooned to 300,000 vehicles a day, with the majority being heavy trucks. As if that were not reason enough to consider an upgrade, the roadway has been in service far beyond its original 20-year design life.
The project will relieve congestion, both on the highway and at the interchanges, and reduce accident rates. In addition to reconstructing all mainline pavement, the project includes sewer improvements that will eliminate flooding and further improve safety.
To construct the new roadway for a 30-year life, the new cross-section of the surface lanes is significantly heavier duty. The typical cross-section of the original highway was 12 inches of aggregate topped with 10 inches of concrete and 5 inches of asphalt pavement. The new highway has a 24-inch aggregate base, 6 inches of asphalt to stabilize the base, and then 14 inches of continuously reinforced concrete pavement, a total of 44 inches.
Jacek Tyszkiewicz, IDOT's chief construction engineer for the region, says that even though the pavement thickness is being increased by 20 inches, the road surface could not be raised and still maintain good clearance under the numerous bridges. In order to accomplish this, the designers and the contractor could only dig deeper. Meanwhile, as the old roadway is being removed, a crusher onsite processes the concrete into two sizes: one with a 6-inch top size and the other with a 1½-inch top size. Both are recycled into the aggregate base. The steel from the old highway also is being salvaged.
The new pavement features ground granulated blast furnace slag (GGBFS), another environmentally friendly component. “We were concerned about alkali-silica reactivity,” says Abdul Dahhan, IDOT mixture control engineer for Region 1. “And we wanted to make sure we get a 30-year life on this project. But with significant ongoing paving work nearby, on the I-80/94 project, we wanted to be sure to not run short of fly ash. So even though there was no specification in place three years ago covering GGBFS, we worked to get it included on this project.”
GGBFS is something new to IDOT work. The contractor has the option to replace as much as 25% of the portland cement with GGBFS. During the express lane work last year, the percentage varied somewhat based on weather, but stayed between 20% and 25%.
“People will see a much brighter concrete than they're used to,” Tyszkiewicz says. The material already has been incorporated into the retaining walls and the express lane paving. It will be used this year in the local lanes as well.
Like any project this size, the Dan Ryan reconstruction involves multiple contractors. A concerted effort has been made to make it possible for smaller contractors to bid on manageable portions of the work. For example, some items, such as landscaping, have been unbundled and broken down into contracts of $500,000 or less. More information about how the program was set up, and how it's working, is available at www.danryanexpressway.com.
Chicago-based Walsh Construction Co. has been the successful bidder on virtually all of the major paving contracts on the project (see Paving in the Fast Lane). The first major paving work was done in 2005, and primarily involved work on the ramps and frontage roads, including retaining wall construction. Then in 2006, Walsh rebuilt the express lanes, which run down the center of the project from 31st St. to the Chicago Skyway interchange, near 59th Street. Although isolated in the middle of traffic, the site was completely segregated from the nearby traffic and large enough to provide good circulation. As a result Walsh was able to place 2000 feet of highway on some days.
Constructing into the future
As work proceeds on the local lanes this year, there will be more of a logistical challenge, Tyszkiewicz notes. Because every other ramp has to be kept open, the paving will be much more segmented. Fortunately, they got a jump start on the local lane work. Last year Walsh constructed the new fifth lane in each direction between 71st St. and 95th St., which crews will use for access as they rebuild the fourth lane. Then traffic will be separated around lanes two and three while they are reconstructed. Finally, lane one will be rebuilt.
One other element of the Dan Ryan received an upgrade. A long elevated structure that runs between 18th and 31st streets, called the “high bridge,” was reconstructed in 1988–1989 and included a 7½-inch concrete deck. As part of the current project, its 236 joints are being replaced. To make the most of the lane closures and shutdowns that were going to be required, IDOT decided also to do a concrete overlay now, at the same time, instead of waiting a few more years and having to disrupt traffic once more. After grinding and hydrodemolition to prepare the surface, the 2¼-inch microsilica concrete overlay was placed during the 2006 season.
The entire Dan Ryan Expressway project is scheduled for final completion in 2007.