For young and old alike, nothing beats the anticipation, excitement, butterflies, and exhilaration of a roller coaster ride. Since summer 2014, riding the roller coasters at Europa-Park, Germany's biggest theme park, has been more  spectacular than ever. That's when the most elaborate indoor attraction in  Europa-Park's history opened to the public. Right next to the Fairy Tale Forest, the park has built a theme ride based on the French children's film "Arthur and the Invisibles." Most of the movie takes place underground in the enchanted garden-like land of the tiny elfin Minimoys. The fascinating dark ride through this fantastic wonderland features numerous special effects.

Fairy-tale ambiance

The building is unusual in architecture and design. The attraction is concealed beneath a 15 m quarter-circular dome connected directly to the hall. The dome rises three meters above all the other buildings in the Minimoy world. The  distinctive greenery covering the roof, dome, and walls near the entrance transforms the building into a verdant primeval forest idyll. Lavish plant cover, richly detailed decorations and a location directly on the Mühlbach stream next to a chestnut-lined path strengthen the fairy-tale ambiance.


A fantastic sensation of flying

Green roller coaster tracks snake their way outdoors from the entry area, then reenter the microcosm on the other side of the building. The park planners developed the theme ride mainly for younger children and families. The passengers sit in cars, but with their legs dangling in the air in an "inverted coaster" configuration.

For the entire ride, the cars are suspended from the rails rather than running on them as in a conventional coaster. This gives passengers a fantastic sensation of flying, carrying them to a height of nearly 15 meters at the highest point of the ride beneath the dome.

A tight seal for the distinctive roof design

Construction began with an enormous steel frame that serves as a supporting structure for the hall and the dome. Gradually the building took on its unusual shape. Box corrugated steel roofing panels were used over the entire newly-built hall. The 3,320 square meter surface was first covered with a self-adhesive aluminum-laminated vapor control layer from Sika Germany. This was followed by a 160-mm layer of mineral fiber insulation. Sarnafil synthetic waterproofing sheeting, also from Sika, was chosen to seal the roof and dome.


Three areas are to be sealed

There were three distinct areas to be sealed: The 2,300 m2 main roof was attached mechanically. To the north it adjoins a 320 m2 sloping roof with a 30 degree incline. The third area consists of the dome, which rises three meters above the main roof, and the quarter circle that descends to the ground. These have a total area of 700 m2.


A special Roof color

Since the sloping and dome roof areas were to be covered in vegetation, the waterproofing membrane had to exhibit a high degree of tear resistance. Sika's root and rhizome resistant Sarnafil TS 77 membrane is ideal for waterproofing roofs with extensive plant cover in combination with a mechanical attachment system. To ensure that the roof would blend seamlessly into the building's design, the client had one special requirement for the synthetic membrane: the waterproofing for the entire roof had to be reseda green. Sika Germany met this special color request. As a result, the building had a distinctive, otherworldly appearance even before planting.


A special challenge: the dome

The dome rises from the building, directly attached to the flat roof and the  façade. In the shape of a quarter-circle it descends all the way to the ground. Beneath it is the entrance to the realm of Arthur and the Minimoys. The lower edge of the 700 square meter dome surface, with a slope of nearly 90 degrees, presented a special challenge. Synthetic waterproofing membranes are particularly well-suited for architectural details like this.


Support on the dome

Sika Germany provided services such as engineering assistance for the dome and sloping roof construction and mechanical attachment as well as visits to the construction site by an application technician.  The slope of the roof and the dome presented added safety challenges during construction. Safety nets suspended from tubular steel brackets were installed around the building and additional scaffolding was erected.


Enchanted greenery

The roof, dome, and walls were subsequently planted using vegetation mats. A cherry picker and additional safety ropes were used to reach the steep roof surfaces. The work on the façade required special precautions. A steel structure at the peak of the dome was used to secure steel cables. Individual panels were pre-filled with substrate and mechanically attached to the steel cables together with the vegetation mats. This load transfer method made it possible to securely  attach the extensive vegetation to the roof sections. The green roof is complemented by artificial flowers at the roller coaster entry and on the  façade.

All this effort has paid off, and the new attraction has been a big hit with both children and adults. Visitor numbers since the ride opened in the summer of  2014 have been well above all expectations.