Riding high with Terex Cranes!

Terex luffing jib tower cranes efficiently carrying the load for the Karlatornet high-rise project

The Serneke Group AB, Gothenburg, Sweden, is in the midst of a multiyear transformation of Gothenburg’s skyline. The SEK 10 billion Karlastaden project is anchored by the Karlatornet high-rise building, a 245-m (804 ft) skyscraper that, once finished, will be the tallest in Scandinavia. 

Just 10 minutes from downtown Gothenburg by public transit, Karlastaden is a condensed mixed-city development covering 32.000 m2 (38,272 yd2) and 10 city blocks. It will feature 2,000 apartments covering 200.000 m2 (239,198 yd2) condominiums, rental apartments, offices, shops, restaurants, a medical center and school. 

The crown jewel, the 73-story Karlatornet skyscraper will rest at the center of the new Karlastaden district. Its location and size will allow the building’s profile to be visible from both the Göta älv River and city center. A top-level observation deck will give citizens and visitors breathtaking views of the city, river and the Kattegat. 

The Serneke Group’s vision is to create a district in which all citizens of Sweden’s second largest city by population can take pride in. Karlastaden and Karlatornet will be an integrated part of the city that is ecologically, financially and socially sustainable and bustling with activity both day and night, every day of the week. 

A perfect fit

Construction activities throughout the development creates a congested construction space for building the new skyscraper. That made the type of tower crane selection critical to ensure lifting efficiency without lines and jibs crossing each other’s paths or requiring one crane to wait for another to complete its lift. 

“We immediately considered the Terex luffing jib crane design for the Karlatornet project because of the efficiency of hoisting movement,” comments Dennis Säfström, Operations Manager for Flens Byggmaskiner AB. “Luffing jib cranes are generally known for great mobility, lifting capacity and hoisting speed.” 

Flens Byggmaskiner, with headquarters in Flens, is Sweden’s leading lessor of construction (tower) cranes and tasked with supplying the cranes for the high-rise project. Säfström initially used a Terex CTT 181 flat top tower crane to test the site for reach and capacity required over the project area. It was determined that two Terex CTL 430-24 and one Terex CTL 272-18 luffing jib tower cranes would offer the capacity and reach to cover the entire construction area. 

Flens Byggmaskiner specially ordered the cranes from the Terex Fontanafredda, Italy tower crane manufacturing facility for the Karlatornet project. “We loaded a total of 60 trucks for the roughly 1.800-km (1,118-mi) trip to the project site,” says Bartosz Irzyniec, Area Sales Manager for Terex Tower Cranes. “This included everything they needed for final crane configurations for this project – tower and jib segments, hoists, bases, counterweight and cabins.” 

It took roughly five days for the trucks to make it to Gothenburg, and Säfström staggered truck delivery of crane components over two days for efficient offloading. “There was limited space for unloading, and we had windy weather conditions for erection,” he says.  

Once the components were unloaded, a team of five people for each crane immediately went to work assembling the cranes. “We had Terex technical sales representatives and service technicians on site to help our crew erect the cranes, and they have provided us with very good support,” adds Säfström. 

Efficient lifting 

The Terex CTL 430-24 luffing jib tower crane offers a maximum 60-m (197-ft) jib length, a maximum lift capacity of 24 t (26.5 USt) and maximum jib length lift capacity of 5.5 t (6 USt). In-service jib operating radii range from 15- to 85-degrees, and when not in service, the jib is set to a 65-degree radius to allow it to freely slew. 

Crew members erected the first CTL 430-24 to a 63,4-m (208-ft) tower height with a 50-m (164-ft) jib. For the second crane, a hook height of 54,4 m (178-ft) was required, and a 50-m (164-ft) jib was installed. All three cranes, including the CTL 272-18, were mounted on anchor feet and equipped with low-temperature kits, service derricks and telematics for reporting critical operating data and fault codes, so issues could be quickly diagnosed and fixed. 

If required at later stages of building construction, the Terex CTL 272-18 crane offers a maximum 61-m (200-ft) jib length. Work crews equipped the crane with 50 m (164 ft) of jib for the first tower construction phase. Initially, tower height was set to offer a 60,4-m (198-ft) hook height. As construction progresses on the skyscraper, it will climb ultimately climb to deliver a 252,5-m (828-ft) hook height to complete the 245-m-tall (804-ft) structure. 

“Above all, we use the cranes simultaneously in the same direction, and the luffing jib design allows this to happen without interference,” explains Säfström. “Therefore, we save time and money and boost lifting operation efficiency because we do not have to wait for a crane that is in the way of another crane.” 

The ability to work independently with the luffing jib design without fear of crane interference is a plus for Serneke Group’s builders as they work to stay on schedule for the construction timeline that will last into 2022. From tools and framing materials to concrete and elevators, all three cranes are tasked daily with making dozens of lifts for work crews. 

“Depending on the load, the CTL 272-18 and CTL 430-24 offer hoist speeds reaching 230 m/min (755 ft/min) and 160 m/min (525 ft/min) respectively to quickly and safely lift and place the material,” says Irzyniec. And all appreciate the efficiency and reliability of the Terex luffing jib cranes. “For this project, the crane operators and Serneke Group think the cranes are doing very well and are perfect for their purpose,” adds Säfström.