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Sat January 03, 2009 - West Edition
The Utah Department of Transportation (UDOT) is one of the state transportation departments pushing the envelope when it comes to bridge-building technology. Over the last two years, UDOT has used Accelerated Bridge Construction (ABC) with Self Propelled Modular Transports (SPMT) for 13 bridges in or near Salt Lake City alone, saving large amounts of time and money compared to traditional bridge-building techniques.
The technology is likely to come into play again soon, because UDOT is planning to replace approximately 500 bridges statewide over the next 10 years.
“One of the things we wanted to do, when we first brought this technology to Utah, was to see how well this technology worked,” said Shana Lindsey, UDOT’s director of research.
In the fall of 2007, UDOT used the ABC method to replace the 4500 South Bridge that crosses over Interstate 215. The bridge was constructed completely off the roadway and then placed with SPMTs. The move took only one weekend and the roadway opened ahead of schedule.
Using ABC for that project resulted in a savings of $4.2 million in user costs, calculating the lost work hours and wasted gasoline that would have accumulated if the bridge replacement had taken the standard six to nine months of traffic delays and closures.
UDOT applied what it learned during that project to several improvement projects, totaling approximately $138 million, in or near the Interstate-80 corridor. This group of projects has been dubbed “Innovate 80,” referring to the use of this cutting-edge technology, which will save an estimated $35 million in user costs. In fact, minimizing the impact on travelers is the main reason to use ABC methods.
One of the most significant Innovate 80 projects is the I-80 State Street to 1300 East project, which will improve a 2-mi. (3.2 km) segment of the east-west corridor. According to John Montoya, UDOT’s project manager for the I-80 project, this major interstate moves 110,000 vehicles a day; 15 percent of those are trucks, many of which are heading to or from west coast ports.
The stretch of roadway and its structures were built in the late 1960s and are “functionally deficient,” as UDOT deputy bridge engineer Fred Doehring puts it, and require total reconstruction and widening. The State Street to 1300 East project includes:
• replacement of pavement along the 2-mi. segment
• improvement of interchange ramps at State Street, 700 East and 1300 East
• addition of one general purpose lane in each direction, bringing the total to four lanes in each direction
• addition of a lane connecting ramps between interchanges
• construction of sound barriers
• a total of 15 structures, seven of them built with ABC techniques
Close Collaboration on Project
When design for the State Street to 1300 East project began in mid-2006, ABC technology was new to UDOT. So the department opted for a Construction Manager/General Contractor (CM/GC) arrangement because it allowed closer collaboration between the designers and contractor.
Time was another factor in favor of the CM/GC arrangement. Montoya estimates that going with CM/GC trimmed a whole season off the project, compared to using design/build or design/bid/build.
Ralph L. Wadsworth Construction Company Inc. (RLWCC), a 33-year-old company out of Draper, Utah, was awarded the $100-million-plus State Street to 1300 East job. The contractor started construction in September 2007.
Phase One, which ran through January 2008, mainly dealt with orchestrating traffic flow. It involved temporarily widening the eastbound lanes to accommodate five lanes, as well as constructing cross-overs at each end of the project.
The use of moveable barriers, coupled with a barrier moving machine, allowed for the middle lane of the five to act as a reversible lane so that peak commuters always had three lanes open, which is the same number they had before construction started. The barrier moving machine, manufactured by Barrier Systems Inc., headquartered in Rio Vista, Calif., made it possible for crews to realign the barrier in less than an hour.
In addition to keeping drivers safer and happier, the moveable barriers also improved safety for the workers, points out Lindsey.
Bridges in the Air
By early December, reconstruction of the permanent westbound lanes (Phase Two) was completed, as scheduled, and the barriers were no longer needed. Three lanes in each direction were available to drivers.
Also in 2008, seven of the State Street to 1300 East project’s 15 bridges were constructed in a pre-casting yard, locally dubbed “the bridge farm,” located in the infield of a loop ramp at 1300 East.
“You’d drive by and there’d be seven bridges, 20 feet in the air,” said Doehring.
Building seven bridges in one off-site location had a number of benefits. For example, improved worker safety translated to a better product overall, according to Doehring.
Doehring said: “It increased the safety for the traveling public, and more importantly, for the workers. They were no longer dangling over live freeway traffic… they weren’t constantly being buffeted by passing semis… that equates to an increase in quality on those bridges.”
Wayne Bowden, RLWCC’s manager for the I-80 project, also mentions worker satisfaction, but in a different context. At peak, workers in the pre-casting yard numbered upwards of 100.
Bowden said: “It was good for the guys, that they all worked together. It’s rare that we have that many guys working shoulder to shoulder, day in and day out.”
A pre-casting yard also is more efficient in terms of equipment, because the same machines can be used to build different bridges—unlike traditional on-site construction, where duplicate equipment is needed if bridges are to be built simultaneously at multiple locations.
As a result, RLWCC was almost exclusively able to use equipment they already owned. The fleet included loaders, Kobelco track hoes, and several cranes (Manitowocs, P&H). Local subcontractor Harper Contracting brought in Caterpillar equipment for the earthwork and pipe work.
Help From Holland
Dutch company Mammoet provided the SPMTs that moved the bridges.
These motorized vehicles feature connectable trailers on multiple axles. With paired axle wheels that can pivot 360 degrees, the vehicle can move in any direction. Due to a complex system of hydraulic jacks, each axle bears an equal load. A joystick-like, portable control panel allows a single operator to drive, lift, steer or brake.
The seven bridges built in the bridge farm for the State Street to 1300 East project ranged from 85 to 173 ft. (25.9 to 52.7 m) long, and from 43 to 94 ft. (13.1 to 28.6 m) wide. The heaviest was 1,350 tons (1,224.6 t). The SPMTs carried each superstructure to its permanent location, moving at an average speed of .5 mph (.8 kph).
As the contractor for the 4500 South Bridge, RLWCC was ahead on the learning curve in terms of ABC methods, but Bowden said that moving these bridges was a lot more complicated.
The 4500 South superstructures were built right next to where they would be placed. By contrast, for the State Street to 1300 East project, the farthest bridge had to be moved .13 mi. (1.8 km) with SPMTs. To move each bridge into place along the State Street to 1300 East segment, the SPMTs had to crawl over a hill, down an on-ramp and along the roadway to reach the destination.
“Moving those bridges was just an incredible feat, in my mind,” said Doehring.
Many meetings took place in advance of moving the seven bridges, during which teams discussed the best way to handle any challenges that might arise. The integrity of underground utilities had to be considered, including a 100-year-old water pipe that was shut down to minimize consequences in the event that it was damaged. Gas lines also had to be protected.
Bowden said: “That was a lot of work—a lot of work—to protect utilities in place to the level that everyone was comfortable with… in the end, it all worked out well. We didn’t damage any utilities.”
Even as the bridges were being moved, the contractor implemented design changes to make the process safer and quicker.
Bowden said: “That was one of the advantages of a CM/GC job: everyone was part of the team. The designers, UDOT, we were all linked together as a team. Changes were easily distributed into the construction.”
Once the SPMTs completed each journey to the permanent bridge site, the superstructure was still above grade and needed to be slid into place on skid shoe rails. That took approximately 11 hours. Then 500-ton (454 t) capacity climbing jacks lowered the superstructure onto the abutments, a 10-hour project that engaged 55 workers. All seven bridges took 41 days to move into place.
The bridge moving equipment, including skid shoe rails and climbing jacks, was sent from Mammoet U.S.A.’s location outside of Houston and stayed in Salt Lake City for two and a half months, over the summer. The SPMTs and other specialty equipment also were used to move five other ABC-built bridges. Four structures further east on I-80 were put into place in less than 24 hours, spread out over two weekends.
The process became streamlined with practice and SPMTs moved the twelfth and final structure, the 3300 South Bridge over I-215, into place on August 23 in less than 18 hours—accompanied by much fanfare from UDOT officials and the media.
Leading the Nation
Fact sheets and news stories stated that Innovate 80 “is believed to be the fastest replacement of 12 bridges in the world” and that “Utah is leading the nation in the development of standard specifications for ABC.” Utah is listed as a lead state on the SPMT team of the American Association of State Highway and Transportation Officials (AASHTO).
The public, too, was fascinated by the bridge farm and the process of moving the giant structures into place.
“We had crowds and crowds of people, which is the opposite of what usually happens,” said Lindsey. “As a result of that, we have a lot of support from the legislature on funding.”
Some of UDOT’s bridge funds come from state money generated by the gas tax, which is a well run dry these days. So the legislature set aside some money from the general fund to bond against.
“In this time, getting any general fund money is a coup,” said Doehring.
In addition, many of the state’s upcoming bridge projects could be eligible if President-elect Barack Obama’s administration decides to supply federal funds for ready-to-go infrastructure projects as part of an economic stimulus plan. According to a December survey conducted by AASHTO, Utah has nearly $11 billion of projects that could be contracted within 180 days of receiving stimulus aid.
In the meantime, crews were braving temperatures in the teens the week before Christmas to continue working on the State Street to 1300 East project, even though UDOT had halted billions of dollars worth of construction projects in November.
As of mid-December, the project had reached its midway point, on time and on budget. Phase Three was underway, including the construction of the permanent eastbound lanes and the building of the final eight bridges, via the traditional manner. The State Street to 1300 East project should be complete by fall 2009.
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