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Nearly 50 years after becoming a forerunner agency in prestressed concrete girder specification, the Illinois State Toll Highway Authority has added to its concrete bridge inventory a new centerpiece. Scheduled for a November 2007 opening, the 1.3-mile Des Plaines River Valley (DPRV) Bridge combines simple span prestressed bulb tee girders up to 170 ft. plus post-tensioned, segmental concrete girders spanning up to 270 ft.

The $125 million structure represents the industry's largest prestressed concrete girder job in 2006-07, and the biggest-ticket bridge in Illinois Tollway history. Appropriately, the $24 million girder package brought Prestress Engineering Corp., the top concrete bridge supplier in Illinois, its largest contract ever.

Rising 90 ft. at it highest point, the six-lane DPRV Bridge is also the largest single contract in the Authority's Interstate 355 South Extension, linking Interstate 55 and Interstate 80 through fast-growth southwest suburban Chicago. The bridge superstructure scheme evolved from a design/build-modeled, performance-based specification contract option the Authority offered with eye an toward expedited delivery. The DPRV Bridge contract was originally to be let as a steel plate girder or segmental concrete box girder design. Success with performance-based specifications on the recent South Tri State Tollway (Interstate 294) Reconstruction and Widening Project prompted Tollway officials to expand the DPRV Bridge bid parameters.

“The bridge crosses two waterways and wetlands that are habitat for sensitive species. That caused the Toll Authority to limit the number of piers disturbing protected wetlands,” explains Brian Slagle, P.E., project manager for Indianapolis-based Janssen & Spaans Engineering Inc., which designed the DPRV Bridge superstructure. “Once we looked at the span lengths, the prestressed and post-tensioned concrete girder design was more suitable than a concrete box girder.” Successful performance-based spec option bidder, Walsh Construction of Chicago, he adds, identified the conventional and spliced bulb tee girder option as the most economical.

The DPRV Bridge and 12.5-mile South Extension, along with the existing I-355 North-South Tollway, will be named the Veterans Memorial Tollway, scheduled for dedication on Veterans Day 2007 (November 11). The bridge spans the I & M Canal, Sanitary & Ship Canal, several railroad lines, Des Plaines River, and a DuPage County Forest Preserve.

The South Extension is part of the Authority's 10-year, $5.3 billion congestion-relief plan, “Open Roads for a Faster Future,” which will reduce travel times by rebuilding or modernizing 90 percent of the system; widening or adding lanes to nearly half the system's 117 miles of existing roads; and, converting 20 mainline toll plazas to barrier-free Open Road Tolling design.

DELAYED JOB WORTH WEIGHT

Prestress Engineering was awarded the original Des Plaines River Valley Bridge contract in the mid-1990s, when the Authority had set the I-355 South Extension in motion. Legal challenges for the entire 12.5-mile job doomed PEC's contract, which entailed teaming up with a key roadway contractor on a precast segmental concrete box girder design.

After clearing courtroom and environmental hurdles, the Authority indicated South Extension contract letting in 2004, noting a potential performance-based specification option on the DPRV Bridge. Sensing an opportunity to bring a prestressed bulb tee and spliced, post-tensioned beam package to the table, PEC conferred with regular customer, Walsh Construction, and consultant Janssen & Spaans on a performance-based spec. Their winning $125 million bid for the DPRV Bridge compared with $133 million and $175 million bids, respectively, for Authority-prescribed segmental concrete box girder and steel plate girder designs.

At $24 million, the girder order has made a permanent mark at PEC's Blackstone plant, 90 miles southwest of Chicago. (The Prairie Grove, Ill., headquarters and engineering office are about 75 miles north of the plant.) “The 600-piece bridge contract was awarded in November 2005,” says Vice President of Operations-Blackstone Terry Muntz. “We had about five months to set up new casting beds, bring in two new gantry cranes and train 80-90 new employees in safety procedures and production. That meant for the duration of the Tollway girder project, we would be operating with nearly double the average payroll. It was a lot of new people to accommodate on a rural but limited site.”

The owner of an adjacent farm sold PEC seven acres for additional bed and storage area. “This is a windswept plain, and we needed to account for weather in the bed design,” Muntz explains. “The best way of maintaining productivity, keeping fabrication on schedule, and optimizing strand use was to build two 400-ft., below-grade compression beds. End frame and beam stressing assemblies efficiently transfer loads to each bed's walls, and eliminate the need for a ground-anchored steel beam more common in such prestressing conditions.” Creative thinking — a repurposing of heavy plastic barge compartment covers as bed shelter pieces — addressed weather concerns for the subgrade work area, he adds.

“By building the bed 10 feet below ground, we minimized the amount of crane height needed for bed-to-storage handling,” says QA/QC Manager Mike Johnson, P.E. “Handling and crane economy were issues because the performance-based specification allowed us to bid girders (90-, 102- and 120-in.) deeper than what the Authority permits on standard Illinois Tollway contracts (72 in.). The bid option also enabled the use of 0.6-in.-diameter strand instead of [the normally required] 0.5-in. strand.”

“On the original contract, we were told it was hard to make money or break even on a first segmental precast girder job,” concludes PEC Vice President of Sales Andy Keenan. “The bid option on the second go-around allowed us to demonstrate in Illinois advanced prestressed and post-tensioned girder practice that has been successful in other markets. Economies gained with the 0.6-in. prestressing strand and girders 90 in. and deeper make us competitive against steel-plate girders on more day-to-day bidding.”

CRITICAL LINK

Shown here at the south DPRV Bridge approach, the I-355 South Extension will serve Will County, one of the fastest growing counties in Illinois, and provide a regional connection that improves north-south mobility between Interstate 55 and Interstate 80. The extension will reduce travel times by 20 percent and provide a more direct route between residences in Will County and areas where jobs are more plentiful, such as the O'Hare Airport vicinity, therefore benefiting the entire Chicagoland region. The South Extension will run through 13 municipalities or townships in three counties and have six interchanges, including those with I-55 and I-80.

PRESTRESSED SCHEDULE

AT A GLANCE

Contract value: $24 million

  • 300 90-in. I-beams, 90 ft. to 151 ft. long. Largest beam is 57.6 yd., weighing 233,300 lb.
  • 252 102-in. I-Beams, 113 ft. to 170 ft. long. Largest beam is 48.3 yd., weighing 200,800 lb.
  • 60 120-in. I-Beams, 120 ft. to 138 ft. long. Largest beam is 63.8 yd., weighing 258,600 lb.

Concrete requirement: 29,506 yd.

Reinforcement quantity: 3,657,530 lb.

0.6-in. strand quantity: 5,844,253 linear ft.

One of the most sensitive environmental issues of the Des Plaines River Valley Bridge design and permitting was tied to preservation of Hine's Emerald Dragonfly habitat. The dragonfly was listed as an endangered species in 1995, a move the Illinois State Toll Highway Authority had anticipated. Agencies reviewing the DPRV Bridge included the Army Corps of Engineers, U.S. Fish and Wildlife Service, and Illinois Environmental Protection Agency.

CRITICAL HABITAT

The design of the bridge was partially dictated by environmental resources, and the entire alignment was shifted to the west to avoid and minimize impacts to a nature preserve. The Fish & Wildlife Service initiated a Hine's Emerald Dragonfly Working Group as a permit condition to guide the Tollway on future HED habitat mitigation and restoration efforts. As group participant, the Authority is required to monitor the dragonfly for a minimum of five years post construction or until agencies state that all permit conditions and restoration efforts are satisfied.

The Authority has been conducting dragonfly studies for at least a decade, providing a thorough perspective of the species' habitat. Dragonfly sightings were noted prior to construction and have been logged throughout the project's duration.

A temporary Des Plaines River crossing was built for trafficking equipment, materials and girders along the project's north end. It is shown here from a larger, low-level bridge over the Des Plaines River used to move equipment during construction of the main DPRV Bridge. In addition to designating haul and work areas, the permit required Walsh Construction to contain wash out from the mixers of pier and deck concrete supplier Prairie Material.

Once the project is complete, the low-level bridge will be turned over to the Will County Forest Preserve for use in connecting trail systems. Tollway staff will use the structure to inspect and maintain the main crossing.

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© 2007 Penton Media Inc.

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