Stratosphere maintenance crew uses plasma to cut demolition time in half
December 12, 2006
The historic High Roller roller coaster, perched atop the Stratosphere Tower on the Las Vegas Strip, needed to be demolished. The question for contractors was what cutting process and equipment would be best to dismantle the roller coaster, all 367, 3-foot, 300-lb. sections of it.
About 900 feet above the Las Vegas Strip, Brian Day uses a plasma cutter to cut apart the Stratosphere's High Roller roller coaster.
About 900 feet above the Strip, Brian Day pauses for a moment and looks down on the early morning Las Vegas skyline.
"I put up the signs there and there," Day said, pointing at the brightly lit casino signs below. The Strip casinos all look small from the top of the Stratosphere Tower and its famous roller coaster, the High Roller.
After 10 years and almost 3 million riders, the High Roller"s time has come. Although it was lifted into place by the Tower crane, more than 110,000 pounds of track from the roller coaster will be going down in the elevator, one piece at a time. Day is one member of the ride maintenance crew who will be doing the demolition work under the direction of Patrick Brinckerhoff, the Stratosphere"s director of ride engineering.
Rising 1,149 ft. above the Las Vegas Strip, the Stratosphere Tower is the tallest freestanding observation tower in the U.S. and the tallest building west of the Mississippi River. Offering a breathtaking view of Las Vegas and the surrounding valley, the Stratosphere also offers some thrill rides for its more adventurous visitors. Three rides—the Big Shot, Insanity, and X Scream—offer all the excitement of an amusement park with the added attraction of being one-fifth of a mile above ground.
Figure 1 & 2
Each 3-ft., 300-lb. section of track was taken down the Stratosphere's elevator and stored across the street (top). Each section of track consisted of three rails, varying in thickness from 1/4 in. to 5/8 in. (bottom).
While these rides spin, turn, hang passengers over the side, or shoot them upward at high speed, the High Roller circled the observation deck at a mild 30 miles per hour. Many considered it the tamest of the rides. Like the Big Shot, which shoots its riders to the 1,050-ft. level, the High Roller has been with the Stratosphere since the beginning, lifted into place by the Tower"s crane during construction. After 10 years it needed renovating and a decision had to be made.
"The High Roller was due for a facelift that would cost well over $500,000," Brinckerhoff explained. "The hydraulics were antiquated and it required a lot of maintenance to keep it in perfect working order. Even with the overhaul, it still wouldn"t be as popular as our other rides. We decided instead to bring it down and look at possibilities for a future project to replace it."
To fit into the Tower"s elevator, the track and support structure needed to be cut into approximately 367 3-ft. lengths, each weighing about 300 lbs. To ensure safety, his primary concern, and speed—his employees were working overtime—Brinckerhoff had to choose the best process and equipment for the job.
Brinckerhoff worked with an engineering firm, Interactive Rides, to engineer a Thern Davit crane to the original front car frame of the roller coaster. The car was pushed into place, the crane was attached above the next section to be removed, and the section was then cut away. Each 3-ft. length of track consisted of one backbone, two running rails, and a few track ties. The cutout section components ranged in thickness from 1/4 in. to 5/8 in. Once cut, the section was hoisted onto a cart, taken down by elevator, and placed into a storage yard (see Figures 1 and 2).
The same people responsible for ride maintenance during operating hours performed the work. All 11 of them had electrical, hydraulic, and mechanical backgrounds. Most of them had some welding experience; three were certified welders. Some were ex-military, others had erected the huge signs that light Las Vegas casinos or worked at other theme parks. All of them were accustomed to working at great heights, according to Brinckerhoff.
Several times a month, four or five crew members worked overtime on the High Roller, between 2 a.m. and 8 a.m., the only time the Tower isn"t open to visitors.
For the demolition, Brinckerhoff initially intended to use the oxyfuel process, augmenting his existing setup with a larger one. Although he had an oxyfuel cutting setup on hand, it presented several risks.
"One of my biggest fears was that if an acetylene tank were to leak, it would seriously compromise the integrity of our building," Brinckerhoff said. "Fire was probably the biggest concern, especially in the Tower. We couldn"t store the oxyacetylene tanks in the Tower because of fire department regulations. So the oxyfuel tanks would have to be transported by elevators every night."
He also became more concerned about using oxyfuel after he discussed it with his crew and maintenance managers at other amusement parks.
"Everyone said plasma was the way to go," Brinckerhoff said. "They cited its ease of use, its speed, and its convenience. With plasma, we wouldn"t have to deal with the logistics and safety concerns of moving gas around, getting it on-site and up and down the Tower."
Brinckerhoff also learned in his research on the process that plasma cutting potentially could slice through a section of track in less than half the time of a gas torch, as well as eliminate the safety and portability issues associated with oxyfuel.
After deciding on plasma cutting, Brinckerhoff sought the right machine for his needs.
"I was fairly open-minded," Brinckerhoff said. "Price was a consideration, but so was the availability of consumables, how much service and support I would receive after the purchase, and the availability of training materials."
He began his research first by listening to his peers" recommendations, then by visiting various manufacturers" Web sites.
"The Miller Web site was very helpful in putting all of the information together," Brinckerhoff said. "It has numerous case studies that show exactly what other people have done, allowing me to associate the products with what I need to do."
He also found that the site had a full set of operator manuals, as well as safety tips and other useful information.
His research led him to choose a Miller Spectrum® 1000, an 80-amp plasma cutter. The cutting performance chart (see Figure 3) showed that he could achieve a cutting speed of 120 inches per minute (IPM) on 1/4-in. material.
Cutting Speed and Material Thickness
The plasma cutter, rated for 1-in. cutting based on a cutting speed of 10 IPM, has Auto-Line™ technology, which allows it to connect to any primary voltage from 208 to 575 volts, single- or three-phase.
"There were several contributing factors to Patrick"s decision, but the two most important were cutting speed and fire safety," said John Aldrich of distributor Nevada Compressed Gas. "The Spectrum 1000 met his needs in both categories."
To see how much time he would save, Brinckerhoff conducted his own cutting speed test, pitting the Spectrum 1000 against the gas torch. He had one of his trained welders practice with the gas torch and then timed him. Cutting a section of track took between seven and eight minutes, although the operator felt that he could bring it down to below seven minutes with practice. With the plasma cutter, the same cut took three minutes, 10 seconds.
"Everyone was working on overtime, so the ability to cut the time in half was huge," Brinckerhoff said. With 367 sections to cut, the cutting time amounted to 19 hours with the plasma cutter versus 43 hours for oxyfuel: a savings of 55 percent.
Fifteen days and one-third of the way through the project, Brinckerhoff said the plasma cutter already had more than paid for itself.
Although the plasma cutter seemed to be the faster and safer option for the project, Brinckerhoff wanted to make sure that all safety practices were adhered to when using the plasma cutter as well.
"We have all of the concerns of any amusement park, but we have them 1,000 feet in the air. When it comes to the safety of the passengers or the Tower, we don"t make compromises," Brinckerhoff said.
"Don"t become part of the circuit; wear the proper safety equipment—a few simple rules," Brinckerhoff said. "We discussed safety and everyone read the manual."
In some instances, Brinckerhoff said, oxyfuel is a viable choice.
"If you have someone who is really skilled with a gas torch, you may be able to forgo the use of a plasma cutter," he said. But in his situation, which entailed multiple users with different skill levels and backgrounds, he said the plasma cutter was the right tool.
After the High Roller project was complete, Brinckerhoff said he planned to use the plasma cutter for other projects.
"We have to do some custom fabrication," he said. "We"ll modify the plasma cutter to be used with a jig table setup."