Twenty-two bridges on a 5-mi. (8 km) stretch of Interstate 80 in Salt Lake City, UT, are long overdue for repairs. The bridges along this stretch of road are more than 30 years old when the typical life of original construction at that time averaged 20 to 25 years.
“We’ve certainly gotten our money out of them,” said Bob Fox, director of communications for the Utah Department of Transportation (UDOT).
The $9 million in federal maintenance funds slated for this project is not anywhere near enough to reconstruct the bridges however, so the plan is to rehabilitate them and extend their life by 10 to 15 years.
“Ultimately they will have to be reconstructed just like we’re doing to I-15, but this has to be the makeshift plan for now," said Fox.
The project’s price could sound like a bargain though, when compared to the $1.5 billion being spent to reconstruct 17 mi. (27.2 km) of I-15. Fox estimated the bill to reconstruct these five miles on I-80 to be in the range of several hundred million dollars.
Before bidding the project, UDOT examined all of the bridges to determine what needed to be done. After analyzing the conditions, a few structures were deemed acceptable and removed from the project list. Those remaining are located on eastbound and westbound I-80 between State Street and Parleys Canyon, Foothill Boulevard over I-80 and I-215, and the ramps connecting I-80 and I-215 near the mouth of Parleys Canyon.
“The critical factor of course is safety concerns,” said Angelo Papastamos, UDOT project manager.
The contractor, Draper, UT-based Gerber Construction Inc., began the project in earnest in late January of this year. The project focuses on the support structure of the bridges — columns, beams, etc. Construction activities include concrete repair, carbon wrapping, and encapsulation of columns. Rehabilitation activities on the bridge decks include joint sealing, waterproofing membranes, concrete overlay and asphalt overlay.
A lot of new methods and products have been developed since these bridges were originally constructed and many are now being used to rehabilitate them. In the past, for example, bridges were designed with expansion joints that are a lot wider than is necessary now. They also were built using black rebar, which rusts, expands and breaks concrete apart.
“In just the last 10 to 20 years we’ve gone to using epoxy coated rebar that keeps the moisture away from the rebar and eliminates some of the problems we’ve seen on these bridges,” said Allen Gerber, project manager for Gerber Construction.
Other improvements in road construction have come in the form of materials to better withstand earthquakes. Since Utah’s Wasatch Front is high on the list of areas predicted to be hit hard sometime soon by earthquake forces, many of the bridges are having some form of seismic retrofit as well.
“These bridges were built before seismic design was a part of the process so we have to go back and retrofit them to meet new seismic standards,” said Papastamos.
Seven of the bridges on State Street, Highland Drive and Foothill Drive have columns that will be wrapped in a carbon fiber that’s designed to keep the bridge from falling down in the event of an earthquake. This product is experimental in Utah and has never before been used by UDOT. California-based Sika-Hexell is providing the carbon fiber wrapping, which has been used in California road construction.
“This carbon fiber is amazing. It’s many times stronger than steel, yet you can cut it with scissors,” said Gerber.
UDOT and the contractor have tested the product at the University of Utah by wrapping models and then simulating forces that break them to perfect the wrapping technique. There will be various layers of the material on different parts of the column because in the event of an earthquake, the middle of the column typically rides it out while the bottom takes most of the pressure.
Gerber explained the pre-production process as similar to the wringer on an old-fashioned clothes washer. The epoxy is first forced into the fibers and then wrung out to bind to the layers of carbon fiber wrapping. The finished product is then applied by hand and smoothed out around the columns. It’s vital that the epoxy and carbon fibers are bound correctly.
“As a team they’re super strong. The epoxy and the carbon fibers are worthless without the other,” said Gerber.
The next step is painting the newly wrapped columns to keep ultraviolet light away and protect the finished product.
With all of these advanced materials and the high cost of rehabilitation, some of the structures may still appear to be unfinished to the passing motorists long after Gerber Construction has moved out.
“The public will look under these bridges and notice some areas are patched and some aren’t, they may also see rebar,” said Gerber. “We hope people don’t think we did a bad job since our name is attached to the project. It’s a solid job but people may not know why it looks that way.”
The reason of course, is tied into the project’s budget. Rehabilitating to make the bridges safe and structurally sound were the number one concerns.
“We’re trying to minimize cost since we know we’ll have to go back and reconstruct eventually,” said Papastamos. “Until you can improve capacity on this road, you’re wasting money.”
Although most motorists would like to have all road construction behind them, many of them would probably agree that capacity is very important. However, that doesn’t mean all Utah motorists are nice to those workers trying to do traffic control.
“We do get the international hello sign quite a bit,” said Dusty Nagle, superintendent of Chatfield Construction Inc.
Nagle didn’t mean a five-finger friendly wave either. His company was hired to provide traffic control throughout the project. His people also have had a few occasions where agitated motorists have gotten so close that they’ve brushed a flagger right out of the way with their vehicles. No one has been hurt luckily.
“We also employ members of the highway patrol for off-duty shifts so people don’t take roads we don’t want them to,” said Nagle. “They help us a lot since most motorists won’t drive beyond the barrels right in front of a police vehicle.”
Nagle believes the key to keeping motorists content is to keep them moving. In his experience, even a very slow pace is much better than actually stopping on the road due to construction delays.
“We couldn’t do this project without Dusty and Chatfield,” said Gerber. “They’ve proven themselves to be invaluable.”
Chatfield Construction has had an average of four workers on the site each day and maintains a 24 to 7 operation.
“Gerber dictates the schedule and we take it from there. Drums, signs, anything that’s orange is pretty much ours,” said Nagle.
Gerber Construction and a handful of subcontractors have had some challenges with the project due to the numerous limitations placed on them regarding traffic control. I-80 is a heavily-traveled road and Gerber Construction had to agree they wouldn’t restrict certain lanes while the University of Utah was in Fall or Winter session and couldn’t close a bridge next to Highland High School until summer break.
“The day after school was out, we closed the bridge,” said Nagle.
Nagle added that Gerber Construction willingly practices a partnership with his company and the other subs to help them do their work without delays, which in turn helps Gerber to move faster. The speed at which they’re able to move and complete the work means more than just a job kept on schedule. UDOT is trying a phased bonus structure called land rental on this project to try and limit traffic impacts. The basic concept of the incentive is that Gerber must “rent” the lane from UDOT from the time Chatfield Construction pulls the lane until the time it’s back in operation.
“If they get finished and off the lanes sooner they get a bonus. If it’s later it will cost them more,” said Papastamos.
Construction bonuses are nothing new and UDOT looked at several innovative packages around the country before deciding to try lane rental. Papastamos added that the verdict is still out on how well this incentive will work and that UDOT will analyze the results after the project is completed.
“There’s been a lot more stress on this project than I envisioned,” said Gerber. “It’s just a lot of hard work and we have guys that are fantastic and we couldn’t do it without them.”
Each bridge is at various stages right now with work currently being done on about 10 of them. In addition to traffic control, subcontractors have been brought in to help with asphalt, traffic striping, drilling concrete, painting, cable x-ray, and concrete delamination. The project is on schedule to be complete in December 2000.
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