Concrete Progress: Connect Fourth

Nov. 24, 2009

Since it first opened in 1958, the Tri-State Tollway (I-94/I-294/I-80) has stimulated economic growth and development in the northern Illinois region. But after nearly 50 years of service to ever-increasing traffic, much of the Tri-State’s pavement was reaching the end of its life cycle, and a major overhaul was needed to reduce congestion and improve service and road conditions for tollway customers.

In 2004, the Illinois State Toll Highway Authority approved a comprehensive $6.3 billion capital program including road improvements on the North/Central Tri-State from Balmoral

Since it first opened in 1958, the Tri-State Tollway (I-94/I-294/I-80) has stimulated economic growth and development in the northern Illinois region. But after nearly 50 years of service to ever-increasing traffic, much of the Tri-State’s pavement was reaching the end of its life cycle, and a major overhaul was needed to reduce congestion and improve service and road conditions for tollway customers.

In 2004, the Illinois State Toll Highway Authority approved a comprehensive $6.3 billion capital program including road improvements on the North/Central Tri-State from Balmoral

Avenue near O’Hare International Airport to the Wisconsin state line.

Budgeted at $1.3 billion, the North/Central Tri-State Rebuild & Widen Project ranks as the largest construction project in Illinois Tollway history.

Heavily numbered

The entire 83-mile Tri-State Tollway functions as a bypass around the metropolitan Chicago area and serves as a commuter link between Milwaukee and Chicago. Stretching from just west of Indiana north to the Wisconsin state line, it serves hundreds of thousands of northern Illinois commuters, commercial truck drivers and thousands more local businesses daily, as well as a multitude of visitors who arrive in Chicago each day at O’Hare International Airport.

Traffic in this corridor has grown dramatically in the past several decades, as more commercial, residential and retail developments have emerged. In 1959, there were an estimated 43,000 vehicles a day traveling on the Tri-State. In the 1970s, when a third lane was added in each direction, average daily traffic skyrocketed to about 275,000 vehicles a day. Today, there are nearly 564,000 vehicles a day traveling on the Tri-State Tollway.

To address current and future needs, the scope of work on the North/Central Tri-State Project included reconstructing and widening to four lanes in each direction between Balmoral Avenue and Rte. 173 near the Wisconsin border.

Work also included reconstructing the roadway in the 2½-mile segment north of Rte. 173 to Russell Road and resurfacing pavement in the 1½-mile stretch from Russell to the Wisconsin state line.

The project also widened and reconstructed nearly 60 bridges, rebuilt about a dozen interchanges and reconstructed two mainline toll plazas—all while maintaining efforts to minimize disruptions to tollway customers.

Over the course of the project, the Tollway Authority reconstructed more than 270 lane-miles of pavement, moved 8 million cu yd of earth, used more than 1 million tons of steel and poured more than 1.4 million cu yd of concrete. On any given day, as many as 3,500 full- and part-time professional and construction staff worked on this project.

What’s old is new

The original roadway was built with a 10-in. jointed reinforced portland cement concrete (PCC) pavement, which was standard at the time, and a porous granular material on top of a select dense-graded aggregate sub-base. But higher-than-anticipated traffic took its toll on the road, accelerating its deterioration over time. And after three rehabilitation/overlay projects, it was time for a complete reconstruction.

Plans for the rebuild and widen project entailed referencing the American Association of State Highway & Transportation Officials design guide in order to design the roadway in accordance with materials standards. Material specifications, as well as quality control and quality assurance, were in line with Illinois Department of Transportation (IDOT) standards for pavement and any reinforcements.

From the start, the Tollway planned to recycle 100% of the existing roadway concrete and asphalt during reconstruction work. It also recycled concrete from the old Culligan International Co. office building in Northbrook and miscellaneous other sources as well. In total, the Tollway recycled nearly 1.6 million tons of concrete and asphalt as new pavement base aggregates on the Tri-State Tollway, including more than an additional 200,000 tons of reclaimed asphalt pavement (RAP) from other sources in the new hot-mix asphalt (HMA) mixtures used for the HMA stabilized sub-base and new bituminous shoulders of the Tri-State.

Reusing existing roadway materials was not only an environmentally sensitive construction method, it also saved contractors and the Tollway money in hauling fees and allowed better quality control of materials. The extensive recycling efforts required the contractors and the Tollway to apply extra quality-control and quality-assurance practices to confirm that consistent and acceptable materials were being produced.

Work began in 2006, with the 3-in. HMA overlay being milled off and stockpiled on-site to be used later in the stabilized sub-base and HMA shoulders. Existing PCC was removed and crushed, often onsite with portable crushers or mobile crushers, for use as the porous granular embankment (PGE) base for the new roadway. The existing or remaining base-course aggregate was then classified as an embankment material and was removed or thickened to the proposed subgrade elevation. In areas that did not meet compaction or proof-rolling requirements, the subgrade was undercut and backfilled with extra quantities of the recycled PGE aggregate.

The common use of mobile milling and crushing equipment allowed for the recycled and reprocessed asphalt and concrete materials to be windrowed along the reconstructed right-of-way to reduce or eliminate the need for truck transportation.

The new roadway was built with a new 12-in. subgrade aggregate consisting of 9 in. of PGE and 3 in. of capping aggregate that consisted of RAP grindings of a CA-6 gradation placed on the compacted subgrade/embankment. A 3-in. HMA-stabilized sub-base was used on top of the 12-in. subgrade aggregate. A 12-in. jointed plain PCC pavement with 15-ft joint spacing was then paved over the HMA-stabilized sub-base. The Tollway used a standard IDOT Class PV concrete mix for all pavements.

Ultimate compressive strength was achieved in three to four days, utilizing a liquid curing compound. The pavement was finished with variable-width tining slightly askew for better control of tire noise. Pavement markings are recessed with slow-cure multipolymer paint for improved reflectivity and better durability.

Double-lane slipform pavers, which measure 30 ft end to end, were used for most of the mainline paving operations. Single-lane slipform pavers were used mainly for paving ramps. A standard paving train was used consisting of a spreader, a paver and a tining machine.

Mainline shoulders were paved with bituminous asphalt utilizing either a standard asphalt paver or a road widener. Both machines used two rollers.

Work also included extensive amounts of noise wall and reconstruction of dozens of bridges. Bridge materials also followed IDOT standards, pouring a 7½-in. concrete deck over steel or precast prestressed concrete beams, with a seven-day wet cure. Concrete conveyors or pumps were used to disperse concrete onto the deck, followed by a bridge-deck finishing machine. A series of work bridges were then used to apply curing materials.

Trying not to disturb

Some bridges, including Willow Road and Belvidere Road (Illinois Rte. 120) also were lengthened to accommodate future widening and reconstruction of local roads, and the Tollway worked closely with state and local agencies to develop cost-sharing plans to minimize future traffic impacts.

As an example, the Willow Road Bridge was both lengthened and widened to provide a six-lane pavement section with dual left-turn lanes on Willow Road. This bridge expansion allowed the reconstruction and widening of Willow Road from Sanders Road to Landwehr Road, which not only helped reduce congestion for the ramps to and from the Tri-State Tollway, but also reduced travel times for local traffic.

Southbound construction was completed in 2008, and northbound work is expected to be completed by the end of 2009. When construction began on the north end of the corridor in 2007, design engineers were busy at work designing plans for 2008 construction contracts. By performing construction while designing work for the following year, the Tollway was able to rebuild and widen the vast majority of the 45-mile stretch of roadway in three years.

In order to rebuild and widen the roadway while maintaining capacity, the Tollway adopted a maintenance of traffic (MOT) plan that provided the same number of lanes during construction that were available before construction. As a result, lane widths were reduced and traffic shifted into a counterflow configuration with express and local lanes. By shifting one lane of traffic onto the other side of the road as an express lane, the Tollway maintained three lanes of traffic during construction with work zones in place behind a temporary concrete barrier wall.

The MOT plan reduced the impact of construction on drivers while providing contractors the space they needed to work for extended periods of time without frequent changes in the work zone.

Additionally, the Tollway coordinated bridge reconstruction by staggering construction schedules, thus providing alternative routes for the local drivers who relied upon the east-west routes crossing over or under the Tri-State Tollway throughout the region. Nearly all bridges were kept open during construction with staged traffic and reduced lanes. The Tollway coordinated work with IDOT, Cook County, Lake County and local government leaders to minimize the impact to local roads.

Farther to the north of the project, the Tollway continues to work with the Wisconsin Department of Transportation on its recently launched reconstruction plan for I-94 from Milwaukee to the Illinois state line. In fact, the Tollway had extended its widening project from Grand Avenue to Rte. 173 in part to coordinate with Wisconsin’s I-94 reconstruction project. The Tollway also is working with IDOT on its plans to widen the roadway between Rte. 173 and the Wisconsin state line.

About The Author: Kovacs is chief engineer and Gillen is materials manager at the Illinois Tollway, Downers Grove, Ill.

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