Gothenburg is Sweden’s second largest city with a population of more than 1 million residents in the metro area. It is located on the west coast of Sweden with a beautiful archipelago and the iconic trams can be seen zigzagging around the city. You’ll also find 30 000 planted trees, 810 kilometers of bicycle lanes and a fish market hall in the shape of a church.
Furthermore, Gothenburg is a center for research with around 3 000 researchers, teachers and doctoral students at the University of Gothenburg. Here, world-class research is being conducted and the university offers some 1 400 courses and 190 programmes, making it one of the most popular universities in Sweden.
Two of the university’s eight faculties, Sahlgrenska Academy and the Faculty of Science, are located at Medicinareberget (Medical Student’s Mountain). Here, education and research in health, medicine and dental care is conducted. The facilities are now being expanded with a new building for future research by the Faculty of Science.
Since the work site is located on a mountain in central Gothenburg, there are several challenges and strict requirements when it comes to rock excavation. Skanska, the project’s prime contractor chose Stens Bergborrning AB as the sub-contractor for the drill- and blast operations.
Henrik Lindström, Production manager at Skanska, shares his view.
"There are four key factors to make a project like this a success; safety, noise reduction, dust management and vibration control. This was very important when we discussed what sub-contractors to bring on. For the drilling operations, Stens Bergborrning AB checks all the boxes. Largely thanks to their choice of drill rig.”
"We are constantly communicating with stakeholders and before the project started, we promised them that top-notch sub-contractors, equipment and methods would be used to minimize disturbances."
The drill rig in question is the SmartROC T35 from Epiroc. It is equipped with a Noise reduction kit that lowers noise levels by around 10 dB, which makes it possible to have conversation next to the drill rig. For this particular project a central dust collector is used, creating a closed system for dust management. Apart from drilling for blasting, the rig will also be used for rock reinforcement and bolting. The hole diameter used for drilling in this application is 64/70 mm and further into the project 45/52 mm drill bits will be used. There will be four benches in total, reaching 20 meters down which means that each bench will have a height of around 5 meters. Blasting times are strictly regulated and limited to two times per week, Tuesdays and Thursdays at 12.30 pm.
Now, drilling in close proximity to existing buildings in an urban environment is always challenging. Considering that these buildings are research facilities in full operation with extremely sensitive equipment makes the challenge even greater. Add to that a rough and unprepared terrain and you have a perfect application for the SmartROC T35. A key feature that gives the drill rig its outstanding terrainability are the oscillating crawler tracks.
Another challenge is to coordinate operations such as overburden removal, drilling, blasting, hauling, and rock reinforcement. This means that planning and communication is essential.
Victor Åkesson, the drill rig operator from Stens Bergborrning AB explains:
“These drill rigs are the best on the market. Especially when it comes to terrainability and stability. Hands down.”
“I have seen people dropping their jaws, they don’t understand how this machine can climb terrain like this without tipping over. Excavator operators sometimes come up to me, saying that they would love to have oscillating crawler tracks as well.”
Victor started his rock drilling career at the age of fifteen. He would go with his father and founder of the company, Sten Åkesson, to different projects and Victor is now an integral part of the company.
"This drill rig has been running for about 1 200 hours since we bought it and just keeps on going. This mountain that we are standing on has to be removed by the summer next year so we really need this kind of reliable equipment."
It is estimated that around 100 000 cubic meters of rock will be excavated before their job is done. That might not sound like much if you were operating in a quarry. In a challenging urban development project like this with blasting limited to two times per week, with adjacent research facilities and strict requirements, it is a huge amount.
Noise levels are measured continuously on site and the SmartROC T35 is way below the required limits. Noise is mainly coming from other machinery.
When the project is finalized and the new building is in place, researchers can look out the window on the top floor and maybe they will spot that famous church. You know the one where they have sold fish since 1874.