Traffic congestion in major metropolitan areas is now a fact of life. We may not like it, but as roads become more crowded with automobiles and trucks, we are spending more time listening to books on tape. As if the sheer number of vehicles were not enough of an aggravation, travelers on Interstate 280, which winds through downtown Toledo, Ohio, live with the added burden of river barge traffic. Even in the age of the Internet and Mars exploration, this method of river transport still closes the interstate for periods that last long enough for traffic to back up beyond the Michigan state line.
Happily, that situation will be alleviated in November with the opening of the $220 million Maumee River Bridge, “the largest construction project in Ohio history,” according to Mike Gramza, Ohio Department of Transportation project manager.
After Fru-Con Construction of St. Louis was awarded the contract, the company selected Henning/Saad Inc. (H/S) of Toledo and US Utility Contractor Co. (USU) of Perrysburg, Ohio, to complete the $7 million electrical contract.
Employees of H/S handled interior work, while the USU team worked outside. H/S crews were charged with stringing miles of wire in a space that is, in effect, a tunnel running the length of the span below the surface of the bridgedeck. That crew was supervised by consultant Bob Colgan, formerly the owner of Colgan Electric, and a presence on many large electrical contracting projects in the Toledo area.
Upstairs, crews working with USU project manager Ed Petersen installed all of the deck lighting, including poles, fixtures, conduit and cables.
To put the project in perspective, consider this: the six-lane bridge will be longer than 29 football fields, and the road surfaces will span 23/4 miles. The main components are a 1,225-foot, cable-supported main span with 150-foot-long approaches at each end, and 12,877 feet of elevated approaches and ramps. An added element is that the new structure was built over the old roadway, making accident prevention a high priority.
The precast segmental deck is one of the largest and most complicated ever constructed, according to Fru-Con. Once on site, the company built 3,058 precast concrete segments that were assembled like pieces of a jigsaw puzzle to became the deck of the bridge. Using a new, high-tech molding process, the segments were built to within tolerances of one-thousandth of a foot, the equivalent of the thickness of a sheet of paper. They range in size up to 60 feet wide and 10 feet long, and weigh approximately 90 tons each. Though common in Europe, the segmented method of constructing a span is not a standard procedure in the United States.
The project will require 186,000 cubic yards of concrete; 3,900 tons of steel post tensioning cables; and 14,000 tons of epoxy-coated reinforcing steel.
The pylon and structure will be supported by a single plane of cable stays designed in a fan-like arrangement that is anchored to the bridge deck. Unlike other cable-stayed bridges, these continuous stays will run across north and south spans through stainless-steel sheaths to cradles, rather than being anchored at the pylon. The largest cable stay consists of 156 strands of wire coated in epoxy; Fru-Con says it is the biggest and strongest ever used on a cable-stayed structure.
In addition to the mechanical aspects of the job was an Ohio Department of Transportation requirement that a local citizens’ art group has input into the aesthetics of the project, a common occurrence in Ohio. The color of the concrete had to be “pleasing to the eye,” for instance. The group also was responsible for developing a landscaping plan for open spaces at each end of the span.
Following the award of the contract, the electricians had six months to prepare for their arrival, a blessing in disguise. “We spent hundreds of hours reviewing contract drawings to determine the most effective and efficient methods of installing cables in the structure,” said Petersen.
An example: “We were required to take a ‘kid-glove’ approach to the installation of light poles and fixtures. The poles are powder coated, and are arc-shaped at their tops. Fixtures are suspended from davits,” Peterson said. That design affected work on 180 35- to 50-foot-tall poles, 100 of which are on the bridge span.
The specifications also called for floodlights to be installed in line with the cables between north and southbound traffic lanes. As a result, Petersen was required to coordinate with contractors producing sections of pavement into which conduit would be embedded, and position anchors to which light fixtures and junction boxes would be attached. That added a number of workers from different disciplines to the mix, all attempting to complete their tasks in tight quarters.
“In some cases, we were forced to work around obstacles placed by others, and still produce fixtures that functioned properly and met the Code,” he said.
Peterson was also required to add expertise in high-tech lighting to his repertoire, since USU was constructing an infrastructure for a lighting system that would illuminate the pylon without knowing precisely what fixtures will be installed. The plan is for the bridge to incorporate LED lights driven by a theatrical processor that will change the appearance of the bridge to meet the seasons: “Red for Valentine’s Day, and green for St. Patrick’s Day, for instance,” he said. However, since that technology is rapidly evolving, a final decision as to the exact components to be installed won’t be made until shortly before the bridge is dedicated.
“We are staying on top of that technology because we’d like to give them what they want on the first go-round,” Petersen said.
Meanwhile, Colgan and crew filled the spaces below the deck with electrical equipment. Central to the initial design of the spaces, Colgan also began preparing for the installation months in advance of his arrival on site.
His responsibility was constructing a system that will illuminate what would otherwise be a long, narrow, dark cavern, and installing light panels, transformers and conduit. The spaces will eventually be used by maintenance crews, and a University of Toledo research team (and their instruments).
“Their task is to measure movement and vibrations on the bridge that may be caused by traffic or weather, allowing the bridge to continuously be fine tuned,” said Larry Henning of H/S.
“When we are done, we will have strung more than 500,000 feet of No. 10 wire and 93,000 feet of ground wire that is enclosed in 90,000 feet of two-inch PVC pipe,” he added. Construction of the pipe was a time-consuming affair, since it included 1,500 expansion joints and 1,305 14-by-12-by-7 in. PVC junction boxes.
Midway through the project, Henning said, “We’ve had no failures, and no problems that we would not expect on a project of this size. It would be impossible for an engineer to anticipate every component or installation method, so things that popped up were of little consequence.”
However, when a specification was unclear or untenable, Ohio DOT and engineers all were involved in approving any change. “And, we were prohibited from drilling a hole in the structure because that might compromise the integrity of the span.”
The biggest obstacle to completion has been weather, which Henning describes as “brutal.”
The DOT’s original estimate for a completion date was fall 2006, but Fru-Con has accelerated the pace dramatically and estimates the job will be finished as much as 400 days early.
“We’re doing well as a result of good planning,” Peterson said.
As the completion date nears, Peterson said, “We have not had any major oops, though the job has presented some challenges. As an example, running internal conduit through thick cement sleeves became a challenge when the sleeves were too narrow for conduit. When new materials were introduced into the equation, that created delays while the DOT and Fru-Con’s engineers evaluated the alternatives.
“What is particularly interesting is the cultural diversity of the project managers and crews. People from several parts of Europe and Asia are involved, many with different approaches than ours, as well as those from all parts of the U.S. We all managed to contribute to a smooth operation,” he added.
Henning is so proud of his firm’s work and says, “I hope that someday my grandchildren will look at this bridge and say, ‘Hey, my grandfather worked on that.’” EC
LAWRENCE is a freelance writer and photographer based in Bozeman, Mont. He can be reached at firstname.lastname@example.org.