Every new attraction marks a tough challenge for those responsible at Gröna Lund: The challenge of fitting it in! The park, located in the heart of Swedens capital Stockholm, measures just four and a half hectares and houses 30 attractions, including three roller coasters. The largest one was built in 1988 and the newest opened in the spring of 2003 to celebrate the 120th birthday of the leasure park. At first sight it's startling that those two coasters share exactly the same location, but for Peter Osbeck, the park´s chief of operation, this is just a natural thing.

The park was determined to add a Wild Mouse coaster and the lack of space resulted in this unusual highlight. Many obstacles had to be taken and at some points it seemed very unlikely that this extraordinary project would ever become reality at all. Finally, Werner Stengel, the ever present roller coaster designer, was willing to join the team and so the small cars of Vilda Musen are now rushing through the support structure of the mighty Jetline coaster. Occasional near-misses of the carriages are expected...

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The roots of Gröna Lund, the "green forest" of Stockholm, date back to the year 1883. A small merry-go-round next to a restaurant and a Vaudeville-show marked the beginnings. About a century later the park which is located near the palace of the Swedish king has become Stockholm's top tourist destination. Its "buildings" seem to outshine the skyline of the nearby city, making Europes highest Free Fall Tower its new symbol. The two spectacular roller coasters are other top attractions.

The modified first drop

At the end of the 1980s the Speedracer Jetline was born out of a co-operation of Anton Schwarzkopf and the German companies Zierer and BHS.

This light-blue steel monster was the biggest single investment Gröna Lund has done to this day. Nearly 800 meters of track are coiled inside the compact steel construction which resembles the mobile Schwarzkopf coasters, except for a first drop and a banked turn which are built over a section of the Tivoli as a special feature.

For the 2000 season this track segment was completely rebuilt, a change that substantially intensified the kick. The first drop was made longer and steeper, so that the seven car trains now reach speeds of up to 90 k/ph. Boosting the thrill even further, the train now dives into a tunnel which is located within a restaurant and a game stall.

Aerial view of Jetline

After dropping 30 meters and hitting 4,5 Gs in the enclosed valley, the trains are heading towards the newly designed banked turn. Precariously close to the water, the train now begins its return trip to the compactly twisted part of the ride. The modifications were successfully done by German steelbuilding company Maurer Söhne in collaboration with Stengel Engineering and offer an experience that is totally contrary to the "hellish adventure" the passengers are now about to enjoy.

Even without any inversions, Jetline is far from being labelled a "family friendly ride". The g-forces are close to the limits of sanity and offer a truly unforgettable and powerful ride. A relentless succession of steep drops, insanely banked helices and tight curves, all taken at constant high speeds, are the trademarks of this trip. At one point the train dives down at a nearly vertical angle into a curved drop just to conclude the mad dash through curves getting tighter and tighter.

This powerhouse of a roller coaster is notorious for making even the most hardcore coaster enthusiasts feel a little queasy, even though it is almost completely lacking serious airtime. However, this doesn't shy away the visitors of Gröna Lund. Counting around one million passengers per season, Jetline is the most popular attraction of the park.

The notorious third drop

Looking at the structure you will not see any signs of eyecandy or attempts of themeing. Actually, it was not intended to look this way. It was planned to enclose the Speedracer with a mountain scenery, just like its almost identical clone Bavarian Mountain Railway in an amusement park in Kobe, Japan. Early designs incorporated the planned scenery so that the whole statics of the support structure were built to accommodate the additional weight of the fake mountain which would resemble a giant model-railway setting.

Therefore columns and supporting beams are more massive and more stable than the coaster would normally require. After Jetline opened and turned out to be a massive success, the managers of Gröna Lund considered any additional spending as superfluous.

The mouse hunt begins...

About ten years later, the oversized support structure was finally going to pay off. Peter Osbeck was looking for ways to add a Wild Mouse to the park. He decided against the tried and proven standard layout, which can be found in abundance on fairs and in parks all over the world. But even a standard layout proved to be too large for the small park. Together with renowned German coaster specialist Wendelin Stückl, who was involved in numerous coaster designs, he thought up three alternatives: Building the ride over an existing oldtimer track, constructing the coaster along the lakeside promenade and even across the water, or through the dense structure of the Jetline coaster.

While the first idea didn't offer enough layout possibilities and the shoreline plan proved to be far too expensive, the only alternative seemed to be the third idea - a roller coaster inside a roller coaster. Peter Osbeck and Wendelin Stückl were very fond of this ingenious idea and after some rough calculations they concluded that the structure of Jetline was indeed capable of dealing with the additional static and dynamic load of a Wild Mouse.

Gröna Lund and the skyline of Stockholm

Another important obstacle was still in the way: How could a second coaster be designed into the dense structure of Jetline with all its criss-crossing track? After all it had to combine clearance and clearance issues and it was supposed to offer a thrilling ride. Only one man could provide the answers to all those questions: Werner Stengel, the coaster designer who was responsible for the design (layout, statics and dynamics) of Jetline.

In 1999 Wendelin Stückl contacted the engineer in his Munich office. But to everyone's surprise, Stengel declined the offer. He thought that the given task was too hard to achieve on first sight. The Swedes refused to be discouraged from the decline and integrated the Wild Mouse track in an existing model of the Jetline coaster from the past. After seeing the model Werner Stengel was finally convinced that the ride was conceivable and began designing the customized track layout of Vilda Musen.

The special CAD model from the Finnish company Cyra was a big help for designing the new coaster. Since Jetline was designed in the mid-eighties there was no digital data available to build an accurate, virtual scale model. By using a 3-D laser measuring device, the needed data could be retrieved and processed. This was a first in the history of roller coaster design. The device was mounted on the adjacent Mondial Top Scan, a windmill-like inverting flatride. The rotating centre pole of the ride served as a starting point for the measuring. A few days later this process was finished and Peter Osbeck is proud to tell us that "the CAD model we generated this way has a tolerance of +/- 15 millimeters on a distance of 50 meters."

Left: High speed into a curve - Right: Close encounter with the S&S Turbo Drop

The coaster manufacturer was quickly found: The upcoming Bavarian company Gerstlauer from Münsterhausen, who had already installed the electrical wiring for Jetline, was contracted due to a good relationship with both Wendelin Stückl and Werner Stengel. The only thing left was the support structure and some additional supports. An Estnian steel manufacturer was hired for this task. "This saved us another 10%" admits Peter Osbeck with a mischievous grin.

All steel components had been put into place by christmas time 2002, and in early January the 430 meters of track were added. Just a week later the works were finished, completing the most unusual Wild Mouse on the planet. The track is criss-crossing through the steel forest of supporting columns, passing the S&S Turbo Drop and the Top Scan which was "misused" just a few weeks earlier. It is remarkable that no major changes had to be done to the park to install a coaster of this magnitude. Just the Traumboot (an inverting swinging ship) by Weber had to be removed to make way for the station building. But the ride was relocated to another spot inside of Gröna Lund.

The camelbacks announce the last third of the ride

Vilda Musen offers a track layout which artfully plays with all the classical elements of a typical Wild Mouse. You'll find plenty of hairpin turns and camelbacks, but the species found at Gröna Lund adds steep, sudden drops and delights its guests with highly banked, insanely tight turns and even a finishing figure-eight sequence.

The layout is actually quite simple, but due to its integration into the structure of Jetline it becomes more than just confusing and unpredictable.

It takes an aerial perspective to finally overlook the layout: After leaving the elevated station, the cars negotiate a 180° turn before the chain lift engages and drags the mouse cars underneath the first drop of Jetline. The lift is followed by a spectacular first drop at 44°, before the small cars continue their race above the Jetline.

The oval layout is full of confusing curves and daring hills and dips, which are all passing above and through the wicked turns of the Speedracer. One hairpin turn just misses the S&S tower by a few inches, shocking and thrilling riders of both rides alike as the two vehicles occasionally fly by each other.

The last drop leads into the helix

After leaving the curvaceous segment, the cars fly over two camelbacks which are placed directly underneath the first drop of Jetline. The next turns are located on the roof of Vilda Musen´s station building. There was simply no room to waste!

Another tight turn follows before the car whizzes by the onride-photo spot and passes a small trimbrake. Then the little mouse dashes wildly through the figure-eight sequence which is placed directly above the heads of marvelling park visitors. This horizontal loop is supported by a steel framework spanning over the midway that also carries the camelbacks as well as parts of the lifthill.

Arrival at the station

Finally the magnetic brakes bring the mouse hunt to an end. Strikingly the brake modules on the track and the brake fins on the cars are only mounted on one side. Peter Osbeck reassures us that despite of the asymmetric deceleration no additional wear and tear is generated onto the axes and the track. Instead of the final magnetic brake, all other block- and security brakes are traditional friction brakes.

Official website of Gröna Lund

Vilda Musen and Jetline are indeed a contrary duo: The single cars of the Wild Mouse are zig-zagging through the obscenely tight hairpin curves, trying to throw their delighted guests out of their seats on the harsh and sudden drops while subjecting them to a rapid fire of constant acceleration and deceleration. Jetline, on the other hand, offers a tightly packed high speed ride throughout its narrow curves, offering a relentless borderline experience of g-forces in quick succession. Add to all this the "close encounters" of the various coaster cars and you are in for a thrilling sensation of the special kind. This duo is a perfect example of how the sum of two good rides can merge into something extraordinary.

Translation by TrickTrack