Stayin’ Alive

As long as people gamble, some things will never change in Las Vegas: Casinos will always be open; neon lighting will always be in style; and the house will always win if you play long enough. And that’s the real secret of success in Sin City: giving people everything they need—accommodations, shopping, dining, gambling and entertainment—all under one roof.

As a result, the constant development of the Strip, whether it is the addition of new resorts or the expansion of existing ones, doesn’t appear to have an end in sight.

Mandalay Bay, host of this year’s NFPA conference, is one such property that has grown notably in its short history. The resort first opened in 1999 with a hotel tower, casino, convention center, events center and theater. Since then, it has executed some ambitious expansion plans, including a new 1.8-million-sq.-ft. convention center, which opened in 2002, a 120,000-sq.-ft. shopping mall and THEhotel, a new 1,120-room tower; these last two opened last year. With this new hotel tower, the resort’s room count is now nearly 5,000.

Exit strategy

Beyond the glitz, hotel/casino properties like Mandalay Bay serve to host large groups of people, all within one complex, making fire safety a top priority. Of all the venues in this particular resort, the new convention center proved the most challenging. According to Armin Wolski, associate with the San Francisco office of Arup, which handled the fire-protection plan for the expanded areas of Mandalay Bay, its sheer size proved problematic.

“Two of the main issues with people that run convention centers is that they want to have the biggest possible space that they can get, and they also want that space to be as flexible as possible,” Wolski says.

In this case, the design for the convention center got to the point where the exhibit halls were so large that they couldn’t meet the code requirements for maximum travel distance to an exit—250 ft. to the corridor, plus 100 ft. to the exit stairs. In fact, the exit distance from the middle of the largest room on the first floor is 450 ft. Luckily, the authority having jurisdiction (AHJ) was willing to consider alternate solutions.

“Clark County [home to Las Vegas] is one of the strictest counties around when dealing with fire protection,” says Wolski. “They make us go through our steps, but they’re also willing to look at engineering solutions.”

In developing a plan to get around the egress distance issue, Arup conducted an extensive analysis. One of the first things they recognized was that considering the 30-ft. floor-to-floor height, the volume of one of the first-floor convention halls—especially when all four sections are open to create a single, 600,000-sq.-ft. space—was so large that even a major fire would take a long time to fill the hall with smoke.

Even so, Arup remained conservative in its estimates and design. For example, the firm used computer fire modeling to compare how long it would take people to exit an exhibit hall with the time it would take for them to be affected by smoke. This, of course, assumed a major fire—the type of which could potentially occur at a boat or RV show, for example—as well as a relatively slow exit rate.

The analysis factored in worst-case scenarios, such as the building’s smoke-control system not triggering and the sprinkler system only being moderately effective. Incidentally, the new convention center utilizes quick-response sprinklers, which react faster and limit a fire to a smaller size.

Even with these considerations, Arup’s analysis determined that convention visitors would have plenty of time to exit in the event of a fire. In addition, the firm backed up its zone modeling of the convention center with computational fluid dynamic modeling, and also used CFD to address smoke spread up the escalator opening from the garage level. Wolski points out that such technology wasn’t prevalent during the initial construction phase but became a crucial element for the expansion elements.

Erring on the side of caution also allowed Arup a clear conscience. “We want to convince ourselves because we put our P.E. stamp to that report, and in the process of working with the AHJ, before we even embark on any significant analysis, we discuss the issue with them and discuss the code requirements,” explains Jim Quiter, P.E., a principal with Arup.

But code requirements are often the minimum design standard. For example, Quiter notes that a portion of the local code—at the time of review, an amended version of the Universal Building Code, but now the International Building Code—stated that in a wide open space, such as an arena or convention hall, where there’s a high ceiling and people can see what’s going on, exits can be smaller. But Arup opted for more and larger exits. “The whole issue of exit width is people being able to get out in time,” says Quiter. “If the code allows you to reduce exit width because people have a lot of time [to reach the exit] in a big space, we thought it would follow suit that people could use more time to travel to the exit instead of lining up at the doors. In most code-compliant buildings, people have plenty of time to get to the exit, but then wait at the exits.”

This wasn’t as much of an issue with Mandalay Place, the resort’s mall, but what did make this portion of the expansion unique was the fact that it was elevated above grade and spanned a roadway between Mandalay Bay and the adjacent Luxor. In other words, patrons aren’t able to simply open the door and walk outside if a fire breaks out. Instead, they exit via pressurized stairways or entryways into either hotel property.

Smoke control

As noted earlier, engineers calculated a significant part of their fire-protection scheme on the basis that smoke-control measures would fail. That being said, the team still had to produce a system that would work, and Clark County has strict code requirements along those lines. According to Donald G. Koch, P.E., principal, JBA Consulting Engineers, Las Vegas, the firm that provided the HVAC and smoke-management systems for the original Mandalay Bay project, as well as the expansions, makeup air velocity was a major issue. As mandated by code it can be no more than 200 ft. per min. for zones utilizing an exhaust method. He explains that since the convention center is open to the casino and the casino is open to Mandalay Place and THEhotel, wind and stack air currents have a significant effect on the air velocities between the smoke-control zones. Noting that JBA tries to simplify smoke-management systems whenever possible, Koch explains that by using exhaust or supply fans to create pressure differentials, they can avoid pressure “sandwiches,” where the floors above and below a fire are pressurized and the fire floor itself is exhausted.

Part of this concept involved using variable-speed drives to control smoke-management fans. This notion proved a bit much for the AHJs, who were in the midst of changing the documentation requirements, and as a result, it took a while to receive final approval. JBA, in fact, had to assure the county that control of the motor and the drive’s programming and functions remained at the fire-command center and could not be overridden locally.

A silver lining in this whole process was the fact that when it came to integrating the existing buildings with the new additions, the expanded areas, for the most part, could be treated separately. “The interface between new and existing could get tricky, because we had to watch the velocities where they were open and provide door closures where they were not,” Koch says. “[Luckily,] the existing and new systems are well integrated. The HVAC and fire-alarm systems, extended from the existing building, were sufficiently sized or upgradeable, so bringing new systems on-line proceeded quite smoothly.”

Pieced together

Compartmentation was a final consideration for the overall fire-safety system. According to Quiter, natural progression between buildings drove the compartmentation design, and firewalls were installed where it made sense. Four-hour filled-concrete-block firewalls were installed between the main hotel and the original convention center. Similar firestopping was put in place between the original and new convention centers, between the main hotel and the parking garage, between the convention area and the hotel’s aquarium and between Mandalay Place and Luxor. Two-hour walls were constructed between the original convention center and the events center, between the main resort and the on-property Four Seasons hotel, between the main resort and the Mandalay Theatre and within the new convention center.

Despite so many components, it was important to hotel management that the designers maintained the feel of one continuous building as patrons passed between areas. Large sliding doors, with exit doors built in, accomplished this mandate. Normally, patrons are unaware that they’re passing from one compartment to another, but in fire mode, Quiter says, the sliding doors close to contain the fire, and patrons can exit through the door within the door.

While the complex is physically split up into various compartments to contain potential fires, Quiter noted that the fire-alarm system, which expanded along with the new building additions, acts as a single, coordinated system. Additionally, the complex contains one fire-control center, but there are multiple fire department response points, equipped with annunciators and controls, so that firefighters can respond appropriately to fire events that are isolated to one area of the complex.

Only in Vegas

Of course, no description of a Vegas fire-protection scheme is complete without noting these facilities’ decor and special features. Every hotel/casino on the Strip has its own theme with accompanying design fixtures, many of which are quite large and made from non-standard materials, and much of the theme-related decor in a casino is one-off material. As such, it may become necessary to test these materials separately to see how they will react to fire before designing the fire-protection system. For example, the mega-screens in casino sports books are often made of plastic. Additionally, the design might call for filling in voids in protected areas that might normally not need to be covered. The question becomes how large of a plastic screen or series of screens is acceptable without a fire break or enhanced sprinkler protection? “There’s a lot of time spent looking at what the interior designer is trying to do and then designing [the system around] that particular piece in a way that makes sense,” says Quiter.

No patience for timidity

In looking back, the Arup engineers feel that one thing that characterizes Las Vegas hotel/casino projects is a fluid, flexible relationship between all involved parties, as well as the ability to act quickly. “If you want to be part of a successful building process [in Las Vegas] and a successful team, there’s no time or patience for anybody who might sit around [after receiving or sending in an RFI] waiting for a response,” says Wolski.

Quiter agrees. “On a successful Las Vegas project—and this is one of them—you end up with a design team that’s talking to the contracting team that’s talking to the owner, and the communication just has to flow smoothly and regularly,” he says. “And if that happens, the building can get built in a hurry.”

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