I-15's Pioneering Spirit

Dec. 28, 2000

Last spring, the Utah DOT (UDOT) and contractor Wasatch Constructors embarked on an odyssey indicative of the spirit that first brought pioneers into the region 150 years ago. The partnership now known as the "I-15 team" is endeavoring to rebuild a 17-mile stretch of I-15 that runs through the heart of Salt Lake City, nearly doubling the number of lanes on the six-lane highway and demolishing 135 bridges in the process.

Last spring, the Utah DOT (UDOT) and contractor Wasatch Constructors embarked on an odyssey indicative of the spirit that first brought pioneers into the region 150 years ago. The partnership now known as the "I-15 team" is endeavoring to rebuild a 17-mile stretch of I-15 that runs through the heart of Salt Lake City, nearly doubling the number of lanes on the six-lane highway and demolishing 135 bridges in the process.

What makes the project so unique, however, is that instead of completion in a standard eight-year time frame, the DOT has deemed the project to be finished in only four-and-a-half years, by October 2001, just in time for the Mormon capital to play host to the world during the Winter Olympics.

While the eyes of the world will be on Salt Lake during the Olympics, the eyes of the roadbuilding industry have been firmly focused on the massive $1.6 billion project since the contract was awarded to Wasatch, a joint venture of contracting big boys Kiewit Pacific, a division of the Omaha-based Kiewit Construction Group, Granite Construction, Watsonville, Calif., and Washington Construction, Boise, Idaho, previously Morrison Knudsen Corp.

The much-anticipated contract was awarded after a three-way bidding competition that included teams led by Brown & Root of Houston and Flatiron Structures, which included Fluor Daniel Corp. and CH2M Hill Cos. Design-build decision.

To meet the goal for completion of the project, the DOT turned to design-build, with the Wasatch team as both the project's builder and designer. Providing the design expertise to the Wasatch team is the joint venture of Sverdrup Civil Inc., DeLeuw Cather, along with URS/Greiner Inc., W.W. Clyde & Co., Parsons Engineering Science and TY Lin International, among others.

According to Tom Warne, Utah secretary of transportation, the decision to go the design-build route for project delivery was made after a survey of the public was conducted. "They told us that if they had to choose they would prefer more pain but less time," Warne told a gathering at the American Concrete Pavement Association annual meeting in Scottsdale, Ariz., in December. At a May meeting of the Associated Builders & Contractors in Ogden, Utah, David Downs, P.E., UDOT's I-15 corridor project director, termed the public's reaction as one of, "If you're going to build it, please do it quickly."

It was a scant 15 months from the time proposals were requested until the contract was awarded, the design-construction team was on board and dirt was being turned on the project, Warne said. While design-build often drives innovation, one technical advance instituted by UDOT during the bidding process that Warne is particularly fond of mentioning is that all the information about the project was compiled on four compact discs and given to the three prospective contract teams. Ordinarily mounds of paper would have been necessary in such a case.

To defray some of the cost of preparing such extensive proposals on the part of the prospective contract teams, UDOT paid each team $950,000. In total, Warne said the department spent $4 million in stipends in order for the prospective contractors to prepare their proposals.

As a stipulation of the proposal process, UDOT was to take ownership of the concepts submitted by each team. The bids were let with the understanding that UDOT could incorporate elements from the proposals of those contractors not chosen for the project.

In order to further minimize some of the start-up time in the process, UDOT performed about 15% of the design work, geotechnical investigation, layout of the corridor and plan and profile work so that right-of-way needs could be determined in advance.

Wasatch's bid wins out

In the end, Wasatch Constructors was chosen by UDOT's selection committee for many reasons, including that the project was to be completed three months ahead of schedule and the proposal was below UDOT's estimate, including construction options.

The team also provided an innovative maintenance of traffic (MOT) plan, on which it was graded highly by the judging team. Elements of the MOT plan included:

  • Keeping three lanes open in each direction south of the project's I-215 junction, except for one 11- to 12-month period;
  • Re-striping the southwestern leg of the I-215 Belt Route to provide four lanes in each direction;
  • Institution of strategic ramp closures to encourage use of alternate routes;
  • The early implementation of advanced traffic management systems (ATMS) to aid the MOT (see related story on p 42); and
  • A public information effort to reduce peak-hour traffic volume by 10%.

According to Bill Murphy, project manager for Wasatch, the experience of the Wasatch team in handling large design-build projects was another factor in the team's choice. The Wasatch team recently completed the $790 million San Joaquin Hills Transportation Corridor, a design-build freeway project in Southern California. The contractor completed the project, which originally was planned to take 17 years, but was designed and constructed in six, three-and-half months ahead of schedule. Murphy, a veteran of the San Joaquin project, proudly displays in his office a recent 1997 design-build award, which he accepted on behalf of the joint venture.

Wasatch's track record also includes the recently completed $126 million design-build project to add four lanes in the median of SR-91 in Orange County, Calif. Construction on the freeway, one of the nation's busiest, was completed eight months ahead of schedule.

"The design-build and maintenance side of this project is different from the San Joaquin project in that we didn't have a full-time on-site sponsor," said Murphy. For I-15, Conway Narby is the principal in charge (PIC) for the Wasatch team. He is in charge of the project's overall quality assurance and public information. Together, these two areas include over 100 team members.

Wasatch also added another wrinkle to the I-15 project in that it chose to set up a hub headquarters that houses the Wasatch design and construction team as well as the UDOT staff and consultants assigned to the project. "The central headquarters was asked for because of money saving and time advantages," said Murphy. "Being here with UDOT, the design process is sped along. Overall, establishing the headquarters has probably been the best thing we've done on the project thus far."

Why reconstruct the corridor?

Typical of much of the nation's interstate system, age and increased traffic have taken their toll on the roadway. I-15 was designed and built in the early 1960s with a 20-year design life.

As the roadway nears twice its expected service life, both traffic loads and the amount of traffic being placed on it are increasing rapidly. The result is more pressure on the pavement and significantly increasing congestion. A recent study by Michigan State University ranked the Salt Lake City area the 42nd most traffic-congested city in the nation. According to recent market research, traffic congestion is one of the top three concerns of Salt Lake area residents.

Interstate-15 is a major high-capacity north-south corridor linking NAFTA partners Canada, the U.S. and Mexico. As a vital economic lifeline to the nation, it carries a large number of trucks, which continue to increase in size and weight.

Although the population of Salt Lake City is expected to increase from 1,250,000 in 1996 to 1,650,000 by 2000, the number of cars in the city are expected to increase at an even more rapid rate.

In addition, the roadway no longer meets modern traffic engineering or earthquake design standards, according to UDOT.

Project scope

Once reconstructed, the corridor is designed to stay in service well into the next century without major overhaul. The concrete pavement, of which the paving portion is planned to begin this spring, will be designed to last up to 50 years and will include doweled joints. The bridge structures will employ high-performance concrete decks and feature a design life of 75 years, as well as seismic design protection. Two new lanes will be added in each direction to the existing three north-bound and three south-bound lanes. Of the two new lanes, one will be for general purpose use while the other will be a dedicated high-occupancy vehicle (HOV) lane reserved for carpools and other multi-occupancy vehicles. As an incentive for commuters into the city to carpool, a new interchange connecting to the central business district will be able to be accessed only from the HOV lanes.

New auxiliary lanes stretching between interchanges are planned to allow more time for motorists to merge into the traffic flow. According to John Leonard, P.E., UDOT's operations oversight manager on the project, most accidents on the interstate occur when entering and exiting the roadway. Installation of the auxiliary lanes should help to reduce the chances of accidents occurring in these areas.

Widening and reconstruction of the roadway is being accomplished on existing right-of-way through the use of retaining walls. Additional rights-of-way are to be purchased to accommodate changes at interchanges and the relocation of frontage roads.

As for the 135 bridges being demolished, they will be replaced by 130 new bridges that are wider, longer and earthquake resistant.

The rebuilding of one particular interchange in the corridor known as the "Crossroads of the West," will take four-and-half years to complete. The interchange, which brings together I-15, I-80 and SR-201 is expected to account for approximately one third of the cost of the project, according to Downs. The reconfiguration of the interchange will provide freeway-to-freeway ramp connections among the three routes, as well as provide route continuity for I-80 to meet federal standards.

Weaving and quick acceleration and deceleration by motorists at the junction of I-15 and I-215, and a nearby interchange, one of the areas biggest bottlenecks, should also be reduced with the addition of a collector/distributor road system.

On the subject of interchanges, SPUIs (pronounced "spooie") are coming to Salt Lake City. Seven diamond interchanges along the route will be reconfigured to single-point urban interchanges (SPUIs). The only new interchange to be built on the project also will be of SPUI design.

"A SPUI has a lot of advantages over diamond interchanges or clover leafs," said Leonard. "They take up far less space than a clover leaf for instance, and they can handle higher capacities." According to UDOT, SPUIs are 30% more efficient than diamond interchanges.

Switching to SPUIs, the department says, increases capacity on cross streets to accommodate traffic, pedestrians, bicycles and buses. In addition, SPUIs require only one traffic light to control all on, off and through traffic.

Accompanying the reconfigured interchanges will be the widening of cross streets, many of them asphalt pavements, at interchanges to three lanes in each direction. Double left turn lanes also are to be added. In coordination with the city's master plan for development and revitalization of its downtown business district, the existing major access is being demolished to be replaced by a totally new SPUI interchange mentioned previously. As part of the city's proposed Gateway rail consolidation project, three viaducts in this area will be brought to grade by as much as two blocks further west than they are currently, opening up tens of acres for redevelopment.

Other improvements include the upgrade, modification or relocation of two-way frontage roads that parallel the corridor in many areas.

In accordance with federal requirements, concrete sound walls are being installed along areas of the route bordering residential areas to mitigate noise. "The homeowners in these areas are happy to be getting the walls," said Downs. To enhance safety, Downs said the median barriers along the corridor will be constructed of concrete.

Aesthetic enhancement to the project includes installation of lighting along the entire length of the corridor. Silhouettes of the surrounding Wasatch Mountains are being incorporated into the project's sound walls, bridges and retaining walls to provide an artistic touch to the structures. Where room is available, wetlands are to be created along the corridor and landscaping will be used to enhance the roadway's visual appeal.

Design tools

To assist the project's designers in creating the plans for the corridor, Sverdrup/DeLeuw chose Intergraph, Huntsville, Ala., as the preferred vendor for civil engineering design and plotting software. "We will have approximately 75 design engineers using Intergraph's civil engineering software for the design portion of I-15," said Bruce Waseli, design manager of Sverdrup/DeLeuw. According to Intergraph, to further increase design productivity, the joint venture also purchased 300 Intergraph workstations.

"We chose Intergraph's civil software because we knew that it offered the design tools we need to successfully complete a job of this magnitude," said Sal Vitale, vice president of Sverdrup Civil Inc. Familiarity with the equipment played a key role in the choice of the vendor. Intergraph design software also was used by DeLeuw, Cather & Co. on the San Joaquin project.

Down and dirty

Much of the first construction season on I-15 focused on two areas: geotechnical work and bridge demolition.

"The intent was to get a lot of the mitigation of poor soils and settlement finished this year," said Murphy. Mitigation work has included the installation of wick drains and the filling of embankments with surcharges in order to achieve settlement. "Now we have to see if our geotechnical assumptions are correct as for how long it will take for settlement to be achieved," said Murphy. Toward this end, fill areas have been instrumented with settlement gauges.

Soon after the contract was awarded in April, Wasatch began mobilization of an army of earthmoving machines: Cat scrapers, dozers, motor graders and soil compactors seemed to be everywhere on the project, along with Cat and Komatsu excavators. While the Wasatch team is bringing over some of its equipment from the San Joaquin project, Murphy said that a lot of new equipment also is being purchased. "This project is different in that for the widening we need to bring in a lot of fill material from borrow sites," Murphy said. In this first construction season, 3 million cu m of fill out of a total of 5 million cu m will have been placed.

The geotechnical design work is being split between the geotechnical engineering firms of Terracon, Lenexa, Kan., and Woodward-Clyde, Denver. Woodward-Clyde is responsible for the northern half of the project while Terracon is the designer for the southern half. Terracon also is providing the deep foundation design for the bridge structures on the project.

The silty sandy soil found on much of the corridor has caused special emphasis to be placed on the geotechnical engineering. The corridor lies on the Bonneville Lake deposits, the original lake that eventually subsided to form what is now the Great Salt Lake. "The soil is extremely soft," said Dan Israel, office manager in Terracon's Des Moines, Iowa, office. Israel knows the project well, having spent five months on site in its initial stages. He continues to make periodic visits to the site.

"The northern area is comprised of three very soft compressible soils," said Israel. "The deposits are normally consolidated clays, sands and silts. In some places the clay layer is 5 m thick. That's what takes so long to drain."

The southern half of the project is more forgiving from a geotechnical standpoint, Israel says. "You get farther out of the wash area," he said. "It's stronger.

"It's been a challenge, but it's been interesting. I think most of the engineers with Terracon have enjoyed working on the job."

The geotechnical engineering is divided into two areas: embankment stability and settlement and retaining wall design.

Embankment techniques

Wick drains and surcharge techniques are being used to drain the soil and accelerate settlement on the project.

"We used wick drains on San Joaquin in two areas," said Murphy. "Because of the soil found here Salt Lake is as good an application for the drains as you're going to find."

According to Secretary Warne, a wick drain basically is a piece of corrugated pipe that is drilled approximately 60 to 90 ft into the ground. The wick drains on the project are supplied by European manufacturer Stabilator, whose U.S. sales office is located in Maspeth, N.Y. The installation of the drains is being performed by Mustang Construction of Matthews, N.C.

"Primary settlement needed to be reached within a period of months instead of years. A lot of the surcharge was necessary due to the very high secondary settlement and the rearrangement of particles." Surcharge is a technique that involves the placing of dirt on top of a final grade for the purposes of preloading it to achieve the desired soil settlement. "You overload it so that you don't have any movement," said Israel.

To verify the degree of settlement, monitoring devices, such as settlement plates and inclinometers that measure lateral deflections, are being employed.

Retaining walls and columns

Four types of retaining walls are being used on the project as well as lime-cement columns and stone columns.

"For the major bridge structures and walls, stability was key," Israel said. "We used a lot of reinforced earth walls with metal grids." Supplied by VSL Corp., Campbell, Calif., the reinforced earth wall systems consist of a metal grid attached to a concrete face panel. A geotextile fabric is placed behind the face panel to prevent cracking. Then the wall is backfilled.

"For deeper embankments reinforced earth was the general wall of choice," said Israel. In some cut situations excavation is to be avoided, such as when residential areas abut the roadway. In these cases, concrete cast-in-place walls were built. However, there are disadvantages that prevent their widespread use. "They are expensive and take a long time to build," said Israel.

Reinforced concrete post and panel walls also have been used on the site. Concrete panels are simply slipped into posts and then the walls are backfilled. The walls are effective until they reach more than 3 or 4 ft high, according to Israel. After that, deflections tend to occur. The walls also can be difficult to use in locations where high ground-water problems exist.

Another innovation incorporated to speed the project is the construction of mechanically stabilized earth (MSE) walls. The walls are constructed of heavy-gauge wire cages approximately 1 ft in height, according to Brian Mauldwin of the I-15 communication team. The cages are filled with a 1-ft lift of dirt and then topped with approximately 25 ft lengths of wire cage material. "The wall is built up in 1-ft sections from there," Mauldwin said. "The earth stabilizes the wire and the wire stabilizes the earth. It's a lot quicker than traditional retaining wall construction that requires backfilling after the wall is built."

Once settlement of the material is achieved, the aesthetic face is applied to the wall. "Lime-cement columns are being installed in areas where we've got real low-strength soils with high walls," said Israel. The columns, which Israel says have not been used much in the U.S., act as bearing materials, serving to reinforce the foundation. The process involves the use of a machine with a mixer attachment that injects the lime-cement material into the ground, mixing it with the surrounding soil. "If the area was excavated it would look like a concrete column," said Israel.

Stone columns are being installed on some bridge abutments and below walls to increase soil strength, which in turn helps reduce the potential of liquefaction during a seismic event. The stone columns are installed using a vibroreplacement technique. The technique involves inserting a large probe into the soil with a vibratory hammer. Rock is poured into the middle of it forming a stone column. Once the rock is poured, the probe is removed.

Bridge demolition

The public's first real face-to-face contact with the project came on May 12 when the first interchange was closed and work crews from Penhall Co., Anaheim, Calif., began a one-week demolition effort. According to Wasatch project manager Murphy, from May through November, Penhall had demolished 30 of the 135 bridges targeted for destruction. Since that time, approximately eight more bridges had been taken down through January, said Frank Glenn, Penhall's senior project manager.

The fast-paced demolition work received a shot in the arm when the project detours were set up and traffic was transitioned to one side of the project, said Glenn. "We are demolishing three to four bridges at any one time," he said. "The project is split into three segments and they each have their own schedules." The demolition work is being performed with nine excavators, including Cat 235, 245, and new 330 and 350 machines. Hitachi 450 excavators also are in operation. The excavators are mounted with Allied hydraulic hammers. As many as five wheel loaders are at work removing rubble, including Cat 950, 966, 973 and 980 models.

The demolition work may be a challenge, but "the cleaning up is the difficult part," quipped Glenn. In addition to being in need of reconstruction due to age, being outdated and in disrepair, Murphy told ROADS & BRIDGES the bridges are being demolished in this fashion because embankment work needs to be performed.

As the demolition work has proceeded, Wasatch crews have begun rebuilding some of the bridges with concrete supplied by contractors Geneva Rock Products, who originally had been part of the Salt Lake Constructors construction team, led by Brown & Root, that had competed for the I-15 contract, as well as Granite affiliate Concrete Products and Monroc.

Bridge rebuilding to date has consisted of concrete placement using pipe piles filled with concrete. "Several footings for columns have been poured," said Murphy.

What's ahead

"We'll start paving in the spring," said Murphy. Wasatch crews will handle the paving duties. "The Cottonwood segment is where most paving will take place."

Concrete batch plants will be set up early in the year. According to Warne, one of the largest concrete plants in the world is being assembled in Salt Lake. "We'll have no problem keeping them busy," he said. On the subject of paving equipment, Murphy said that although the Wasatch team has a good deal of equipment available from the San Joaquin project, the contractor is purchasing a lot of new paving equipment for I-15.

According to Ken Kelly of concrete paving equipment manufacturer Gomaco, his company will be providing pavers, trimmers and tinning-cure machines, as well as a bridge deck finishing machine for the project. CMI Corp. also is providing equipment for the project.

"The bidding for the project is taking place in stages," Kelly told ROADS & BRIDGES. "Once the paving starts, we'll probably have several people on site for training."

When the bridges are rebuilt, the bridge decks will be constructed of high-performance concrete, incorporating silica fume, as well as other possible add mixtures to provide long-lasting strength to the decks.

Business is booming

A project the size of I-15 means increased business for equipment makers and materials suppliers alike. For some makers the project has helped take their businesses to all-time highs in sales. One such company is North Central Crane & Excavator Sales Corp., Mokena, Ill., a division of the Wisconsin-based Manitowoc Co.

Last spring North Central received an order to provide Kiewit Construction Group with $13 million worth of Manitowoc and West-Manitowoc crawler-mounted lattice-boom cranes. The order was comprised of six Manitowoc Model 888 cranes, two newly introduced Model 777 cranes and five West-Manitowoc Model 222EX cranes.

The order, the largest ever received by North Central, was placed for delivery in 1997 and early 1998. According to North Central, Kiewit placed the order to continue the ongoing upgrading and modernizing of its fleet of cranes to meet the demands of a record-setting workload. In addition to the I-15 project, some of the cranes were bound for use on projects in Boston, Indonesia, Puerto Rico and other North American locations.

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