|October 21, 2001
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William R. Tolley
Construction Writers Association
Chicago Works to Revive Wacker Drive
Shoveling, wrecking, planning, building, breaking, and rebuilding are words the poet Carl Sandburg used in his 1916 poem, "Chicago," to describe the action taking place in the City of Big Shoulders. The same words apply today as the city is at work reconstructing its 75-year-old Wacker Drive, still a vital cog in the transportation engine that drives Chicago's business district. Citing the deteriorated condition of the thoroughfare first envisioned by the renowned city planner Daniel Burnham, Chicago transportation officials began a two-year $200 million reconstruction of the street last February. The 1.2-mile east-west portion of the 2-mile double-decker roadway that runs through the heart of the city along the Chicago River was completely demolished and is being rebuilt by Walsh Construction Co. of Chicago.
Two representatives from the Chicago Department of Transportation's Bureau of Bridges and Transit, Denise Casalino, P.E., assistant project director, and Stan Kaderbek S.E., P.E., deputy commissioner/chief engineer, spoke about the project during CWA's midyear meeting in the Windy City held October 5, 2001.
The roadway's upper level is a major transportation artery for the north and west sides of downtown, while the lower level provides access to service entrances for 57 high-rise buildings. Together, the two decks serve 70,000 vehicles a day, half on each level. But the roadway no longer meets modern standards for lane widths and clearances, and it's crumbling, say officials. "It's in poor condition and shoring has been needed in recent years to keep it in operation," Casalino said.
The design life of the new Wacker Drive, once completed in November 2002, is 75 to 100 years. Goals of the "Revive Wacker Drive" project are to rebuild the structure; improve both access and safety on the lower level for deliveries to existing and expanding businesses; ease the flow of traffic on adjacent streets; enhance the streetscape; and develop a river walk along the Chicago River in association with the reconstruction effort. Historic preservation also is part of the project. For example, the limestone cladding and balustrades that line the river along the street will be restored using similar Indiana limestone. Lighting fixtures along the riverfront will be replicated to resemble those used in the 1920s.
The project presents logistical challenges in that 20 streets and the city's transit system intersect the roadway, 12 ramps connect the upper and lower levels, and 19 movable bridges connect to the street. According to Casalino, some entrances to the lower level will be closed as part of the reconstruction. In addition, the lower level, which previously was open to the river, will be closed, in essence becoming a tunnel.
Each level will feature three lanes in each direction with a service lane. A specially developed flat-slab, longitudinally post-tensioned, reinforced, high-performance concrete cast-in-place system will comprise the mat on both levels. "It acts as a one-way slab system that is transversely post tensioned as well," said Kaderbek, who adds that a 2 1/2-in. latex-modified-concrete overlay will be added to the driving surface as a wearing course.
A 32-ft. by 32-ft. column grid will support the upper level. Many of the original caissons are being used, but more than 200 new caissons will be installed in areas where improved roadway geometry is needed, said Casalino. Heavy federal oversight is being applied to the project because federal funds are being used and because similar projects, such Boston's Central Artery, have been criticized for large cost overruns.
Construction Writers Association is a nonprofit, non-partisan, international organization for professional journalists, writers, editors and publicists serving the information needs of the construction industry. CWA has over 200 members, meets at least twice a year, and publishes a quarterly newsletter.
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