What Is a Single-Rail Roller Coaster?

Single-rail roller coaster
Six Flags

Conventional roller coasters, whether they are wooden or steel, use two rails. As the term implies, a single-rail roller coaster features a track that incorporates one rail. Think of it as a monorail, with the train hugging a single beam—except this monorail is capable of turning upside down and delivering a thrilling, yet smooth ride experience.

There have been a few isolated examples of single-rail roller coasters through the years. But the concept never really took hold. For the purposes of this article, a "single-rail roller coaster" refers to the coasters designed and manufactured by Rocky Mountain Construction. The ride company is planning to debut the first two of its single-rail coasters in 2018 with Wonder Woman Golden Lasso Coaster at Six Flags Fiesta Texas in San Antonio and RailBlazer at California's Great America in Santa Clara.

The iBox Track Is Key

A wooden roller coaster typically features a wooden structure with a two-rail track that is made from stacks of wood. The trains ride on thin strips of metal that are affixed to the tops of the wooden stacks. There are many variations of steel roller coasters. In addition to sit-down models, these include: inverted, in which the train hangs suspended beneath the track; floorless, in which the train has no floor (or sides) and passengers ride above the track with their feet dangling; and wing, in which the cars are located on either side (or the wings) of the track.

Regardless of the category, nearly all steel coasters use two rails of tubular steel track.

RMC disrupted the amusement industry with the introduction of its innovative iBox track. The first ride to feature it was the New Texas Giant, which opened in 2011 at Six Flags Over Texas in Arlington. The company took the Texas Giant, a traditional wooden coaster that had become excessively rough, ripped out the wooden track and replaced with its steel iBox track. The converted, hybrid wooden and steel coaster is now wonderfully smooth and hugely popular. RMC has successfully transformed many other aging, rough coasters, including Twisted Colossus at Six Flags Magic Mountain.

Instead of a rounded tubular steel track, iBox track is flat on top and shaped like the letter "I." The train's guide wheels fit into the side channels created by the "I" shape. RMC's single-rail coasters will also use iBox track. Instead of two narrow rails, however, they will use one wider rail. The company refers to it as "Raptor Track." Unlike RMC's hybrid wooden and steel coasters, its single-rail models will include a steel structure and steel track.

Why RMC's Single-Rail Coaster May Be Remarkably Smooth

The single-rail rides will look unique. They will require fewer supports than a typical steel coaster. And while their single rails will be wider than either of the two rails on a conventional tubular steel coaster, they will nonetheless be quite narrow at 15.5 inches across. The rides will give the appearance of a thin ribbon of track unspooling in the sky.

The single-rail concept should deliver a unique ride experience as well. Because the track will be so narrow, the trains will also be narrow. Each car will only have a single seat. Passengers won't have anybody sitting to the left or right of them. Because the track will be hidden under the center of the train, it will seem as if riders will be floating, mysteriously suspended in the air.

With few supports and only a single rail to navigate, RMC says the rides' elements will feature unusually quick turns and twists. They could unleash some powerful G-forces and bursts of airtime. The first two Raptor Track coasters will include three inversions. Despite being flipped upside down and subjected to abrupt changes in direction, passengers should enjoy especially smooth rides.

While steel coasters are generally less rickety than wooden ones, they can still be rough. That's partly because the two rails can be misaligned in sections. If the left and right rails are even slightly out of whack, the trains can shimmy and shudder. Since RMC's rides will only have one rail, there won't be anything to get out of whack.