Six Flags’ latest roller coaster is an engineering and fabrication feat of physics

June 2014 - A steel box tube houses the structure of the latest roller coaster to open at Six Flags Great America in Gurnee, Illinois. With a 180-foot drop at its tallest point and reaching 72 mph, the coaster has the world’s steepest drop on a wooden coaster—the lift hill is a 45 degree angle and actual drop is at an 85 degree angle and a maximum 3.5 G-Force.

The “Goliath” has a steel box tube that was built first upside down. Then six layers of wood were placed one at a time, clamped, glued, screwed with a ram set and nailed on top of one another to connect to the steel top, according to engineers at Rocky Mountain Construction in Hayden, Idaho. The wood was then trimmed to the necessary specifications and placed on the predesigned steel box tube.

A traditional roller coaster has eight layers of wood with a small, thin piece of 4-inch running steel. The six-layer design allowed engineers and designers to “include more extreme elements that have never been done before on wood coasters,” according to company officials.

Steel’s strength, challenges

Rocky Mountain Construction chose steel because the site was too narrow to use a wood structure for the lift hill. “Using steel allows us to meet the loading requirements with less structure.” The company used approximately 800,000 lbs. of 3/8 in.-thick mild A36 steel. 

The installation crew of 35 worked from September 2013 to June 2014, six days a week, 10 hours a day and worked 7 days a week closer to the opening. 

Using plasma cutters and MIG welding the steel, fabricators found acetylene cutting torches worked best in the field when installing the coaster. Fabricators used welding positioners, such a rotating circle to weld small parts. The wheel hubs are made from aluminum and liner is polyurethane. 

The 2013 – 2014 winter season in Chicago was one of the coldest the area has experienced in years and workers had to trudge through, meeting scheduled deadlines to get the coaster up and running. Although all prefabricated parts were made at Rocky Mountain Construction’s Idaho shop, the steel truss in particular presented challenges to both design and build as steel is much less forgiving than wood, according to engineers. 

The roller coaster officially opened June 18, 2014.

Photos courtesy of Kim Johnson, Rock Mountain Construction.