Quad Cities drivers will breathe a sigh of relief when a $30-million project to rehab bridges in the area is completed in 2004.

Interstate 74 divides Illinois diagonally from the eastern edge where it enters the state from Indiana at Danville to where it exits Illinois into Iowa at the Quad Cities. The Quad Cities are comprised of Moline and Rock Island on the Illinois side, and Bettendorf and Davenport on the Iowa side. The Interstate 74 bridges cross the mighty Mississippi connecting Illinois to Iowa. Interstate 74 also passes over the nearby Rock River.

The bridges needed an upgrade to meet the demands of the Quad Cities region and traffic flow. The I-74 Rock River Project consists of replacing bridges and the concrete pavement approaching the bridges. According to Illinois Department of Transportation (IDOT) District 2 Construction Engineer Brian Holliday, “We are replacing four bridges on I-74. Two over the Rock River and two over Interstate 280.”

Holliday said that construction began in late 2001. “Last fall we constructed two crossovers for traffic control. We replaced the concrete lane at the south end of the job at the south crossover.”

The crossover was just part of the beginning of the project. IDOT also is rehabilitating the pavements approaching the bridge and improving the ramps at the interchanges of John Deere Road and Interstate 280 as well as replacing the bridges.

“We started on a temporary work platform, a tramway between the two existing bridges across the Rock River,” Holliday explained. “We used the existing piers of the two bridges for the supports and took beams from the existing westbound bridge for the tramway beams. While we removed them we used them for the tramway. We then put wood crane mats on top of the beams for the tramway surface. This makes for a great work platform.”

This year the goal is to complete the westbound bridges that cross over the Rock River and Interstate 280. Next year, the eastbound bridges are slated be completed.

As of early June 2002, two piers still needed to be completed on the westbound bridge over the Rock River. The new piers will sit on caisson shafts that were drilled into the riverbed. Holliday explained that the columns were poured in bedrock for the new bridge. “A permanent casing went down until we hit rock, then we drilled 16 to 20 more feet into the bedrock,” he added.

Aldridge Electric from Libertyville, IL, was the subcontractor responsible for the drilling phase. The general contractor in charge of this $30-million project is Civil Constructors. The East Moline office is the branch working on the I-74 job. Holliday said that Aldridge provided the specialized drilling machines for the pier caissons. The drill bits for the rock varied from 2 to 3 ft. and up to 5 ft. (.6 to .9 m and up to 1.5 m). “They pick and choose the bit by how hard the rock is,” he said.

Once the caisson shafts were drilled and concrete columns poured, web walls were placed between the columns. Holliday explained that web walls consist of 2-ft. (.6 m) concrete walls. On top of the columns, a pier cap is placed then steel beams are set on top of the cap. The westbound I-280 beams have been set and the bridge deck is being poured. The Rock River bridge spans are progressing from each shore and working toward the center. The southern beams are shorter than the northern beams, and both end beams are much shorter than the long span of the center beam spans.

Holliday said the Rock River bridge has a ramp from I-280 to I-74 that will actually be part of the bridge requiring the use of curved beams. He said this is the first time he has seen the placement and looks forward to seeing how the contractor installs the beams. The completion date for the westbound bridges is Nov. 22, while the completion date for the eastbound is Nov. 21, 2003.

As of June, the contractor is on task and working well ahead of the projected deadlines. However, one item that may cause delays is the flooding that occurred during the first week of June. The Rock River, which flows into the Quad Cities area, was expected to reach flood level during that time and be out of its banks covering a local road the contractor has been using for the construction process. The Sterling, IL, area received approximately 8 in. of rain on June 4, causing flooding downriver and locally.

As with many projects, this one also has incentives for completing the project early and disincentives for late completion. The monetary incentive or disincentive is $8,400 per day.

The IDOT is using the Real Time Traffic Control Message System during this project to assist motorists in deciding on the best roadway to choose. The Real Time Traffic Control, Holliday explained, works through sensors, which collect data on speed and traffic. Then a central computer sends messages to the signal boards and can alert motorist of possible delays. Another name for the Real Time Traffic is Intelligent Transportation System.

IDOT, the Iowa Department of Transportation as well as Civil Constructors are working together to ease the burden of traffic woes on I-74 for the Quad Cities region For those drivers in Illinois, I-74 is an important byway and one of few major highways that crosses from the Indiana to the Iowa border

For more information, visit www.dot.state.il.us/i74