than $4 million in user costs.5 User costs can be defined as “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.” They are part of UDOT’s method of looking at total project costs, including road delays.6 More than 150 highway agency representatives, contractors, and consultants from neighboring states watched the bridge move and attended UDOT’s three-hour workshop on ABC and SPMTs after the bridge move.5 A year later, in 2008, an ABC “bridge farm” was created at a large single staging area to replace seven of the 15 bridges located on I-80 from 1300 East to State Street in Salt Lake City.11 The seven prefabricated system bridges ranged from 85 to 173 feet long and 43 to 94 feet wide, with the heaviest bridge weighing in at 1,350 tons.6 Workers constructed these bridge superstructures at the staging area before transporting them out of the bridge farm, over a hill, down an on-ramp, and along the interstate to the bridge sites using SPMTs moving at an average speed of 0.5 mph.6 There was some difficulty with the first bridge move, but all seven bridges were moved into place within 41 days.6, 11 The use of ABC with SPMTs shortened the project schedule so that it was completed in two years instead of the predicted three years that would have been required for conventional construction methods.11 Several additional bridges in 2008 were also moved into position with SPMTs that summer, including an additional four bridges on I-80 and the 3300 South Bridge over I-215 East.6 ABC methods were used by the contractor Wadsworth Brothers, the engineer Stanley Consultants, and the SPMT specialist Mammoet due to the long detour required by traditional construction. Workers placed the four bridges in 37 hours over two weekends using SPMTs. The placement took less than the 48 hours permitted by UDOT.4 The 80-foot wide, 130-foot long and 800-ton bridge at 3300 South was moved into place in under 19 hours, which was 36 hours less than the 55-hour window provided for the bridge move.6, 14 Slide-in bridge construction was first used in Utah in 2009 with the SR-66 Bridge over Weber River by the selected contractor for the project.4, 15 A large driver for using a prefabricated system was the cost of a detour to the nearest bridge during the construction work.4 For the same reason, plus a strict limit on the permitted road closure time, the contractor Flatiron and the designer Stanley Consultants used bridge slides to replace two I-80 bridges near Echo Junction.4 This was quickly followed by another bridge slide for the I-80 bridge over 2300 East and two SPMT bridge moves for the US-89 bridge over I-15 and the Pioneer Crossing Bridge.15 In 2010, the first use of an ABC multi-span bridge superstructure launching came to Utah with the South Layton Interchange over I-15. Baker designed the bridge as “an hourglass-shaped 218-foot long two-span bridge” that is 220 feet wide at the abutments and 135 feet wide at the center support.16 The bridge was built by RLW Construction, with contributions from HW Lochner and Nordholm Rentals.16, 17 Accelerated settlement was required at the bridge abutments due to the local soils, so the bridge embankments were temporarily surcharged by a minimum of 12 feet of soil above the finished road surface. Workers built the bridge superstructure on temporary steel supports 15 feet above the surcharged soil in four months.16, 17 To minimize delay, the soil settled while the bridge superstructure was constructed; once the approximately 13 feet of anticipated settlement had occurred, the two sides of the bridge could be lowered and then launched into place. The steel girders fabricated by Utah Pacific Bridge and Steel, the concrete bridge deck, and the concrete parapets, with a total weight of 1,150 tons per bridge superstructure per side, were launched from both sides of the bridge using hydraulic jacks.16 Workers slid both sections of the bridge across Teflon-coated surfaces until they met at the center support to form the completed bridge.16 The I-15 lane closure permit was for six hours, but moving the South Layton bridge into place took only five hours. The I-15 Utah County Corridor Expansion (CORE) DesignBuild Project in 2011 widened the freeway by two lanes in each direction for a 23.5-mile stretch, rebuilt and reconfigured 10 freeway interchanges, and rebuilt or replaced 63 bridges. The general contractor for the project was Provo River Constructors, which consisted of four construction firms: Fluor from Irving, Texas; Ames Construction from Salt Lake City; Ralph L. Wadsworth (RLW) Construction from Draper; and Wadsworth Brothers Construction (WBC) from Draper. The design team on the project consisted of HDR, Inc. of Salt Lake City and Fluor from Irving, Texas, with Michael Baker Jr., Inc. of Midvale and Jacobs Engineering of Salt Lake City as major subconsultants. With 1,600 workers at the peak of construction, 300 full-time engineers involved in the design, and 400 additional engineers in support roles, the I-15 CORE project was completed in 36 months.18 The project was delivered under budget and ahead of schedule thanks in part to ABC technologies such as PBES in the form of standardized Utah pre-cast bulb tee shape girders, pre-cast half-depth deck panels, and the use of SPMTs with prefabricated systems. More than 500 pre-cast girders from Hanson Structural Precast in Salt Lake City were installed throughout the project. During weekend closures, more than four bridges constructed at various staging areas near I-15 were placed via SPMTs. The most notable closure was the Sam White Bridge.18 The replacement of the Sam White Bridge over I-15 in American Fork was the longest two-span bridge ever moved by SPMTs in the Western Hemisphere16 and the second longest two-span bridge moved in the world at that time.11 MBI designed the 354-foot long, 80-foot wide, 7-foot deep bridge that weighed 1,910 tons and used six continuous steel girders fabricated by Utah Pacific Bridge and Steel.11, 16, 17 The Sam White Bridge was built in a staging area approximately 500 feet from the existing structure and then moved into 39
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