Published in March 2008

Mine-Blowing Experience
By Martin Palicki

 How Dollywood rurned a roller coaster ride into an AV adventure.

"Explosives" lurk inside the Mystery Mine, thanks to fiberoptics and pyrotechnic effects, operated by a fail-safe show control system.

 As the storm descends, thunder crashes and debris thrashes atop the open mine shaft. Suddenly, a spark ignites a stash of TNT and the whole mine explodes, sending mine cars careening out of control….

Sounds like a scene from a Hollywood thriller, but it actually is the climactic ending to Dolly-wood’s latest roller coaster project, Mystery Mine, which repeats every 30 seconds every day of the park’s operating season.
Dollywood is a regional theme park, situated at the base of the Smokey Mountains in Pigeon Forge TN. Herschend Family Entertainment owns the park, along with several others, including Silver Dollar City in Branson MO. In 1986,
Dolly Parton bought into the park with Herschend, and rebranded it as Dollywood.

Long History

The park has a long history of providing top-notch rides and Broadway-caliber shows, but it wasn’t until 2005 that the company decided it was time to merge the two. “Dollywood was growing swiftly, so we needed not just an attraction, but an icon that stood above the rest,” explained Anthony Esparza, corporate senior vice president of Guest Experiences for Herschend. “We had to create an attraction that really delivers a super experience that people would go home and talk about, and take Dollywood to the next level.”

The “next level” to which Esparza is referring cannot be defined easily, but it is an arena long dominated by major park chains, most with parks located in Orlando. Mystery Mine was a ride that could get Dollywood there, but it required merging the concepts of a roller coaster and a dark ride, and being able to integrate the systems typically found within the two.

Roller coasters traditionally focus on speed and thrills derived from throwing the human body in as many different directions as possible. Modern coasters rely on sophisticated ride control systems that monitor where cars are on the track, how fast they are going and how close cars are to one another.

Dark Ride

A dark ride, by contrast, relies on story and special effects to take riders through a slow-moving experience. Typically heavy on AV systems, dark rides utilize show control systems to fire effects at specific moments. Bringing the two genres of rides together into one package was no small task, and the project would require a host of contractors scattered around the continent to design and construct the ride.

Brian Dudash was contracted by Herschend as the project producer and ultimately was responsible for ensuring that all the pieces fit together. “We knew we were bringing together individuals and companies from a variety of disciplines, and that planning was critical,” explained Dudash. The project timeline allocated one full year of design work to be completed before the first speaker was wired.

Canadian-based Forrec, Ltd., was contracted to complete the design for the project, which had been started by Herschend’s own in-house creative studio. “Our studio created about 10 different ride concepts, and when we started testing ideas with guests, the Mystery Mine idea rose to the top quickly,” explained Esparza. “We’ve worked with Forrec before to pick up the ball and they flesh out the documentation and story development once the idea is set.”

Herschend determined early on that the ride had to be heavily themed, and that required creating not only the look of an abandoned mine, but the ambiance and mood of one, as well. That required integrating AV technology and the accompanying services of Edwards Technologies Incorporated (ETI).

The Queue

“The experience starts with the music played in the ride queue line,” said Mitch Hartmann, ETI’s project manager for Mystery Mine. Many of the attraction’s 108 JBL speakers are hidden within the landscaping and queue hallways. The attraction had custom music composed, but the speakers also regularly broadcast ambient sounds one might associate with a decrepit old mine. One scene in the queue includes an old gramo-phone that periodically comes to life to play ghostly music. Four Alcorn McBride 8-TraXX MP3 players store the audio files and are prompted by the V16+ show controller to play at set times.

ETI was also asked to integrate the audio system in the queue area to the ride’s paging system, so ride operators would be able to communicate to guests waiting in line important information regarding safety or operational updates. Herschend also asked ETI to tie into the parkwide paging system, which was not initially included in the attraction’s design.

According to Hartmann, the problem wasn’t as big as it could have been. “We had utilized a BSS BLU80-8X8-U DSP-based audio processing system, which is easily configurable and was capable of being modified easily.” There were extra inputs open on the processor so, when Herschend was able to extend the park’s paging audio line to the new attraction, it was simply a matter of connecting it and making a small software change to the system. The result allows Dollywood staff to make park-wide pages that reach individuals who are waiting in the mine’s queue.

The Ride

Once on the loading platform, guests board eight-seat mine cars and begin their journey into the dark mine. The coaster equipment was supplied by Gerstlauer, a European manufacturer known for producing compact, reliable rides that make use of a completely vertical lift. Most roller coasters include a lift hill set at a 30 to 45 degree angle. Gerstlauer’s heads up at 90 degrees, which made the coaster ideal for a mine theme.


“We chose Gerstlauer because their ride system fit in well with the stories we wanted to tell,” said Esparza. “We go to trade shows such as IAAPA knowing what ideas we are working on, in this case the story of an abandoned mine, and search out products that help turn that story into reality.”

The coaster’s path has roughly four different sections. The first segment is indoors and takes riders past more props and mine scenery. According to Hartmann, most of the audio and visuals in this area are continuously looping and are not triggered by the location of the cars. The first segment ends with the cars stopping at the bottom of a fog-enshrouded lift hill. The fog effect was one of two special effects systems from Orlando-based Entech Creative.

Water-Based Fog

The fog is entirely water based and is created using 85 misters that run at 1000psi. Bob Hartline, VP of Systems Engineering for Entech Creative, designed and installed the system, which runs independently of the ride control system. “Water-based foggers don’t require special fluid that can leave an oily residue over time,” said Hartline. However, the misters do create a humid environment that can wreak havoc on mechanical and electric equipment. The ride’s roller coaster components are typically designed for outdoor use and stand up to excessive moisture easily. The speakers and lighting, however, had to be considered.

ETI’s Hartmann considered it a “normal coordination item.” ETI and Entech communicated the AV and special effect systems locations to each other during the process, which allowed ETI to select appropriate components and situate them appropriately within the ride building. “The JBL Control Series components are durable and a good choice for theme parks, as they are often used in outdoor installations,” said Hartmann.

The first vertical lift hill takes cars out of the mine and into the ride’s first outdoor section. The cars then race around a short section of dips and turns before returning to the mine for the ride’s third section.

The ‘Chimney’

Once back in the mine, riders quickly find themselves at the base of the ride’s second and tallest vertical lift. As the car starts to rise, riders stare straight up at what appears to be the open top of the mine, as an ominous sky brings in a violent storm. Lightning and thunder ensues and, just as the cars approach the peak of the lift hill, the storm whips a large piece of debris onto the top of the mineshaft, plunging riders into darkness.

Most of the ride’s AV systems are contained in this one section, which is housed in a 125-foot tower that project producer Brian Dudash affectionately refers to as the “chimney.” Built just large enough to house the ride structure and effects, the chimney was a challenge to construct.

When guests look up at the sky above them, they are really looking at a projection screen brought to life by a Panasonic PT-D5600U digital video projector. The media is housed on an Alcorn McBride IS-HD player (since discontinued) that was chosen for its ability to play Windows Media WMV-HD files. It was a relatively low-cost high-resolution display. ETI looked at a variety of HD Media Players ranging in price up to $5000, but settled on the IS-HD based on its reputation as a robust player that provided a good, sharp image.

Initial design plans called for a rear projection, with the screen to be laid parallel to the ground and the projector situated above, pointed directly down. Herschend approached ETI with a concern about the design. The screen would be flat, so they were worried that dirt buildup on the surface would prove challenging to clean and, more importantly, reduce the quality of the image, because the dirt would be between the projector and the screen. A new design was required. “In order to resolve the dirt issue, we knew that rear projection was not going to be a possibility,” explained Hartmann, “but switching to front projection brought up a host of other problems.”

Screen Parameters

The screen was angled to about 45 degrees and the projector was moved so it sat and projected parallel to the ground. Although this front projection setup addressed Herschend’s concern, it created an immediate challenge with the projection geometry. With one end of the screen closer to the projector than the other, and the projector situated at a right angle to the line of sight, the image had severe keystone distortion.

Most projectors currently on the market, including the one chosen for Mystery Mine, have digital keystone correction built in, but utilizing that feature causes the image to retract from the edges, shrinking the image area. It leaves unused pixels and is a waste of the available light.

In order for the projection to be effective, it had to fill the screen completely. ETI realized that the only solution would require projection of the entire frame, which meant the keystone correction would have to happen in the media itself. ETI worked with media producer Ted King of Five Star Entertainment to create a mockup of the system. By projecting grids onto the model, King was able to calculate the adjustments required to pre-distort the media, providing a crisp and clean image that utilized the full screen.

As riders look up, they actually look through an eight-foot-square frame that cuts off the edges of the projection so the image fills their field of vision, just as the roofless walls of a mineshaft would frame the real sky above. The resulting projection, combined with audio and lighting in the chimney, creates the illusion of a convincing storm that sets the stage for the ride’s explosive finale.

Out With A Bang

After the mineshaft is plunged into darkness, the ride vehicles come to the peak of the lift hill and pause momentarily, where they can barely make out a stockpile of TNT in front of them. A swift-moving trail of sparks races toward the explosives as the room in front of them suddenly bursts into flames and the car moves forward and drops straight down into the remainder of the ride course.

The imposing Mystery Mine structure not only hides most of the roller coaster track, but the entire AV system and special effects.

Herschend contracted Ralph Nielsen to oversee design development, scenic production and field art direction. Much of his work focused around bringing this scene from design to reality. Nielsen chose to use fiberoptics to create a series of dynamite fuses, and worked with Oregon-based Fiberoptic Lighting, Inc., to make it happen. According to Fiberoptic Lighting’s CEO Hyla Lipson, the overall length of the fuses was a little more than 37 feet; individual fuses went from 34 inches to 61 inches in length.

Fibers were threaded into a curvy piece of six-inch-wide dibond. The fibers were close together and in a jagged pattern to replicate a length of fuse. The fibers protruded two inches above the substrate and were covered with dirt and clipped on site.

Overall, 6658 fibers were used. Because the effect takes place at the top of the tower, the light sources were located in a different and easily accessible area of the ride for maintenance purposes. As a result, the fiber lengths are long. More than 38 miles of fiber comprise the special effect (202,074 feet, to be exact!). The effect is powered with five 50-watt halogen lamps. The motors operate at 8rpm and fuse duration varies from 2.88 seconds to 4.0 seconds. The lamps are controlled externally and tied into the ride’s show control system.

Fuses ‘Ignite’ TNT

The fuses “ignite” the stockpile of TNT, resulting in a very real explosion. Entech created the pyrotechnic display, which sends a burst of fire 15 feet away from riders every 30 seconds. The effect had to be repeatedly reliable and safe.

The control system for the pyro effect is self-contained and any variance in standard conditions will shut down the effect, but not the whole ride system. A Pilz Safety PLC monitors the safety of the system. The Safety PLC checks the gas pressure and ensures it is within the small safety window. It verifies the pilot lights are lit, that the burners are burning for the proscribed time, and it also monitors the airflow to ensure the fan systems are removing the hydrocarbons from the area. Two oxygen sensors monitor the level of oxygen, ensuring there isn’t too much or too little for the effect to fire properly.

The system has its own proximity sensors on the track, ensuring the trains are in the right position for the effect to fire. Additionally, the only input received from the ride’s show control is a verification of the train’s location, as determined by the show control system’s own proximity switches. The pyro system verifies that the show control system agrees with its own determination of the train’s location. Any deviation results in the effect being shut down.

“Everything is sequence checked and validated,” explained Entech Creative’s Bob Hartline. “Safety is our Number One concern, so the system shuts down to safe whenever a discrepancy arises.” ETI worked with Entech to ensure the AV equipment could stand up to the heat produced by the effect. Knowing the dynamics of the ride during the planning process helped them to make informed decisions about which products to use, such as the JBL 25AV units, which Hartmann selected based on both audio performance and the product’s ability to exceed the Mil Spec 810 rating to withstand temperatures up to 120 degrees F.

Back On Solid Ground

After averting the explosion, the cars plunge down a steep drop and back outside for a final few inversions and twists before returning back into the ride station and exit. Although riders may have felt like they were trapped alone in this haunted mine, in reality, they were being observed all along.

In addition to dispatching trains, ride operators are responsible for monitoring riders during the ride. ETI was charged with providing a security monitoring system throughout the ride. Eight Weldex bullet cameras were installed along the ride course. Infrared LED illuminators were included to allow operators to see riders in the dark caverns of the mine.

The surveillance system was actually expanded through a later change order. “These days, the surge in the security market has made many of these items commodity components easily secured and integrated into the existing AV architecture,” said Hart-mann. Surveillance cameras are tied into an eight-channel DVR on the network that continuously records input from the cameras. Once the six to eight hours of recording time is reached, the park can choose to record over the material or save it, should evidence be needed because of a problem.

Images from all eight cameras are fed into a monitor, where the ride operator has the option of cycling through individual cameras or viewing four at a time on a split screen. The PC-based system is on the company’s network and allows managers to browse and view the system’s images from any remote location with an internet connection.

Worry Free

Mystery Mine opened to the public after a year of design work prior to construction. Problems were surprisingly minimal.

An unusually cold and snowy winter for Tennessee caused some minor delays for installers, but most problems were resolved quickly. Construction of the ride track was finished a month before the AV crew arrived, so the show control proximity switch locations had to be established with the cooperation of the coaster construction team.

The roller coaster track ventures in and out of the building, and houses proximity switches that register with both the ride and show control systems exactly where each car is on the track.

“We knew where effects were going to be located along the track, so we just made sure that the proximity switches were available in locations far enough out that the cars would have passed before the effect could have fired,” added Hartmann. “It’s easy to add a delay to an effect if the switch is placed far ahead, but there’s no remedy for a switch that is too late, other than to physically move the switch further back on the track.”

Hartmann had received detailed 3D CAD renderings of the track ahead of time, and Forrec had indicated where AV effects were needed in the ride sequence, so it was just a matter of ETI determining where power and cables were needed. One adjustment was required when it came time to install the ride’s four subwoofers in the “chimney.”

The building structure was designed to be just large enough for the cars and the safety zone around them. Mounting the subwoofers, each weighing about 250 pounds, would have required reinforcing the structure and altering its appearance. Instead, the subs were mounted inside the lift track structure, after receiving clearance from Gerstlauer that the added weight and vibration would not compromise the ride structure.
Other than those minor adjustments, the process was unencumbered by problems. “It really is a credit to the entire team, who each contributed their tricks of the trade to create a high-caliber ride experience within the framework of a moderate budget,” said Esparza.

Clearly, the hard work paid off for Dollywood, which received critical acclaim for the ride, along with a healthy boost in park attendance. “Ultimately, there are three things that help make any AV project proceed efficiently and on time,” claimed Brian Edwards, president/CEO of ETI. “A solid and experienced team that communicates well with each other, a sufficient amount of planning and problem-solving time, and a clear and concise vision from the project owners.”
Of course, knowing that Dolly Parton would be at the grand opening celebration probably didn’t hurt, either.


Edwards Technologies, Inc. (ETI)

For two decades, Edwards Technologies, Inc. (ETI), has designed multisensory media and control systems, creating captivating environments to entertain and inspire audiences. ETI’s work can be found in theme parks, corporate headquarters, museums, libraries, casinos, restaurants, retail stores and entertainment venues worldwide.

Recent projects include the Isle of Capri Hotel and Casino, LEGOLAND California, British Petroleum’s Campus 1, Levi’s Retail Stores, Skirball Cultural Center and Battle Stations 21 at the Great Lakes Naval Base.

For more information, go to


Entech Creative

Entech Creative Industries is a leader in the creation and building of award-winning brand destinations for the retail, theme park, entertainment and museum industries. With decades of experience among its team members, Entech’s services range from show action systems and interactives to themed environments and complex icon structures.

Clients include Universal Studios, SeaWorld, The Smithsonian Institution, Toys“R”Us, FAO Schwarz, Fort Motor Company and Nickelodeon.

For more information, go to



4 Alcorn McBride 8-TraXX 8 independent MP3 players
1 Alcorn McBride DMX Machine lighting controller
1 Alcorn McBride IO64 show controller
1 Alcorn McBride IS-HD HD video file server
1 Alcorn McBride V16+ show controller
2 Bittree 969 Series patchbays
4 BSS BLU80-8X8-U audio DSP
1 Dell Optiplex 745 desktop computer
2 ETS PV843 extended baseband Cat5 baluns
1 Extron MTP 15HD RS Series HD-twisted pair
interface, transmitter, receiver
1 JBL ASB6118 subwoofer
3 JBL ASB6128 subwoofers
65 JBL Control 25AV speakers
33 JBL Control 25T speakers
11 JBL Control 28 speakers
1 Linksys EZXS88W Etherfast 10/100 Autosensing
workgroup switch
1 Panasonic PT-D5600U video projector
8 Pepperl + Fuchs NJ40-U1A2 inductive proximity
6 QSC CX 204V amps
7 QSC CX 404 amps
4 QSC PL6 amps
2 RDL STM2X mic preamps
1 Rose Electronics KVM-4UPH/SW Vista KVM switch
1 Speco DVR-8TN digital video recorder
1 Totevision LCD-1900VR LCD monitor
8 Weldex WDB-5457DN bullet camera w/IR LED

List is edited from information supplied by Edwards Technologies, Inc.


Fiberoptic Lighting, Inc. (FLI)

Fiberoptic Lighting, Inc. (FLI), creates and fabricates fiberoptic displays that can be used for signs, architectural enhancements, branding, themed environments and graphic murals. In the business for more than 20 years, FLI’s products are UL listed and are recognized internationally.

FLI’s work can be found in theme parks, museums, retail outlets and corporate settings around the world.

For more information, go to


Freelance writer Martin Palicki covers the amusement and themed entertainment industry. He edits and publishes IPM: Inside Parks & Museums (formerly InPark Magazine), and sits on the Themed Entertainment Association’s international board (

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