Precast Solutions

A Winning Edge

The United States’ most expensive privately funded construction project incorporates precast concrete.

By Bridget McCrea

Tucked between the Bellagio and Monte Carlo on the Las Vegas strip is a development that to date is the most expensive privately funded construction project in U.S. history. When completed, CityCenter Las Vegas will be a $7.4 billion, 68-acre “city within a city” that eventually occupies the space between the Monte Carlo and Bellagio casino resorts.

Unlike many of the existing developments in Sin City, this one has a “green” side: With hidden parking structures, rooftop gardens, green space (for parks), an on-site power plant and ample space for pedestrians, the project has achieved LEED certification from the U.S Green Building Council. MGM Design Group owns the development, with Phase I slated for opening in November 2009.

Demolished to make room for this giant project were The Boardwalk Hotel and several local establishments. Being constructed in their place is the CityCenter Resort and Casino featuring a 4,000-room, 61-story resort and 165,000-square-foot casino (designed by Cesar Pelli, Pelli Clarke Pelli Architects); a 400-room Mandarin Oriental Hotel/Residences (designed by William Pedersen, Kohn Pedersen Fox Associates); a 400-room The Harmon Hotel/Residences (designed by Foster + Partners); a 1500-unit Vdara Condo/Hotel tower (designed by Rafael Viñoly, RV Architecture LLC); and twin, 350-unit luxury condo towers Veer (designed by Helmut Jahn, Murphy/Jahn Architects).

CityCenter will also include 500,000 square feet of retail and entertainment space (Daniel Libeskind); 225,000 square feet of convention and meeting space; 900,000 square feet for back-of-house operations; a 2,000-seat theater; a 70,000-square-foot spa; a 7,500-car parking garage; an on-site fire station and power plant; and people movers.

A better choice

Hidden in the morass of construction cranes, materials and workers are a number of precast structures, namely reinforced box culverts that form the pedestrian and utility tunnel sections running between the project and surrounding structures. Jensen Precast of North Las Vegas manufactured the pieces, and got involved after project engineers decided that using precast would save time and make for easier installation (compared with poured-in-place) in the tight working conditions. Since the original pieces were installed, Jensen has been called upon to manufacturer other precast products for CityCenter.

“For the first phase, they were looking for alternate designs to pouring the huge tunnels in place,” says Tim Brown, Jensen’s general manager. “To facilitate time guidelines, accommodate tight working conditions and save money, they looked at box culverts that are traditionally used in storm drain conveyance. They approached us about it, wondering if we could offer them a tunnel in the form of precast.”

Brown and his team, which included Norm Downey, project manager, got to work reviewing CityCenter’s existing plans to make sure that Jensen’s box culvert designs indeed met specifications for the job site requirements. “We then negotiated the price, made the sale and worked on the engineering and design,” says Brown, who then turned the project over to Downey for production, delivery and installation, the latter of which was handled by The Perini Building Co.

Brown says Jensen worked with the project engineers to modify their existing plans to accommodate precast while also providing structural engineering work, product manufacturing, delivery and supervision (for setting it in place). The products were completed within 45 days of the project owner’s order placement, according to Downey, and had to be installed in sections on the crowded work site.

“We couldn’t lay out the entire project at once and had to do it in sections,” explains Downey, who estimates that the tunnels took about nine months to make and install. “They had to be installed one section at a time due to the need to excavate and backfill, and then move onto other sections of the development.”

Timelines were critical for Jensen, which made 1,200 lineal feet of precast box culverts in 12-foot by 10-foot sections, for a total of about 120 pieces. “It was an accelerated schedule,” says Brown, who adds that more than 1,000 lineal feet of trenches had to be excavated prior to installation. “All of this had to be in place before they could start the above-ground construction.”

No hoops in this game

Precast’s distinct advantage over poured-in-place, says Brown, was the fact that the latter would require a heavier wall, more reinforcement and the need to lay the materials out in vertical and horizontal sections. “They would have to pour the floor, wait for it cure, and then wait for it to be inspected,” says Brown. “Then the sidewalls are poured, and the materials have to cure and be inspected. The roof goes on next, and after another inspection it can be backfilled.”

Having to jump through all of those hoops on a project of this scope would have created major time delays and also incur higher costs than using precast, says Brown. “We were able to lay out the pieces in 10-foot lengths – all manufactured and ready to install as soon as the area was excavated,” he explains. “That allowed the contractor to do a small section, backfill it and move onto other parts of the project.”

Jensen, which handled the structural engineering for the project, used a wet-cast design mix for the box culverts. According to Brown, the finish that resulted was the perfect complement to the site’s existing structures. “The result was a very smooth finish that you’d normally see on poured-in-place products,” Brown adds. “It has more of an architectural finish to it, whereas most of the storm drain products designed for underground are made with a dry-cast design, which inherently gives them a rough surface.”

Brown, who estimates that CityCenter’s owners saved about 60 percent in this phase of the project by using precast concrete, says Jensen used existing cranes (of which there are about 39 on site) on the job site to move the products into place. Tight work quarters presented challenges, he adds, and required that the precaster in some instances stage the material on single-deck trucks before delivering it on site.

The 70-foot-long air intake tunnels that circulate air in and around the parking garages, for example, are made from precast concrete. For those, Jensen manufactured four tunnel sections, each of which houses fans and would have “originally been made from poured-in-place,” says Brown. “We reviewed their requirements, created a precast design, manufactured them here in our plant and shipped them over,” says Brown. “They were in place within a day, versus the several weeks – and higher costs – that the poured-in-place would have taken.”

The end result was a happy customer who has since rethought the use of poured-in-place concrete in several areas of the project. “We took a tremendous amount of poured-in-place work and used our internal design and engineering resources to provide more precast products to the site,” says Brown.

As CityCenter’s construction progresses, it’s likely that even more precast concrete will be used to create the dozens of underground and above-ground structures that will make up the gigantic mixed-use project. Expected to be one of the world’s largest environmentally sustainable urban communities, the project kicked off in July 2006 and its first phase is expected to be introduced to the world in November 2009.

Bridget McCrea is a freelance writer who covers manufacturing, industry and technology. She is the winner of the 2007 Florida Magazine Association's Gold Award for best trade/technical feature statewide.

Project Details

Project: CityCenter Resort and Casino, Las Vegas

Description: A $7.4 billion, 68-acre urban “city within a city” on the Las Vegas strip

Owner: MGM Mirage Design Group

Contractor: The Perini Building Co. and Tishman Construction Corp. (executive construction manager)

Precaster: Jensen Precast of North Las Vegas