In with the new
High-tech tunnelling through two mountains in northern Norway is paving the way for more accurate, productive and safer construction sites.
Ten kilometres south of the Arctic Circle, surrounded by the majestic scenery of northern Norway, PNC Norge AS is creating a new road that will travel through two mountains and over one lake. Home of the midnight sun, the Bratland community is tightly flanked by towering mountains and clear blue fjords. Hundreds of visitors flock here in the summer to walk the varied mountain pathways, swim, sail and fish in the surrounding water. The access roads around the area are narrow enough to make any driver nervous as large trucks clatter past. It is one such road that PNC is revising – Route 17. The existing coastline road is slipping slightly and runs at its narrowest past the Liafjellet, a tall mountain with a steep face. In winter it’s not uncommon to have avalanches close the access road completely, cutting off communities and businesses north of the area. At these times, the only form of transport is by aircraft and boat, both of which are often delayed or cancelled due to poor weather. At the site, project manager Norbert Hoerlein runs operations with energetic confidence. Hoerlein has been working in the tunnelling industry for 20 years, mostly in Austria and Germany. It’s his and PNC’s first tunnel project in Norway.
“The project is a five-kilometre stretch of road that will travel through two mountains – 1,900 metres through Liatind, plus a 400-metre-long tunnel through Bakliholtan, and then bridging over the Olvikvatnet lake,” he says. The road will be 8.5 metres wide – much better for those large trucks – and avoid the steep mountain face and avalanches that come with it. It’s actually a relatively small project for the PNC group, costing around 330 million Norwegian kroner (43 million US dollars), but that makes it ideal for the company’s first venture in Norway. Before coming to Norway, PNC had existing connections with Sandvik from previous projects.
About PNC Norge AS
With its headquarters in Vienna, Austria, the Porr Group is the one of the largest building contractors in Europe, providing services in all areas of the construction industry. The company has operated in Norway since 2016 under the name PNC Norge AS. It operates nationally and internationally in areas of civil engineering, including roads, tunnels and special underground constructions. Porr also specializes in project development, environmental engineering and facility management.
Since the Norwegian project required a powerful and reliable drill rig, the company decided Sandvik would be the perfect partner to take on the challenge. Site engineer Ines Hagspiel has become all too familiar with the unique tasks PNC faces at the base of the mountains. “The main challenge during the tunnelling process is to get as little overprofile and underprofile as possible,” she says. “That’s why we need a drill rig that is very accurate, so that we only get a minimal theoretical profile.” On site they’re making the most of the latest jumbo, Sandvik DT1131i, and iSURE tunnel management technology alongside Sandvik rock tools, drill bits, rods and training, resulting in an economical, precise and fast drill and blast process. “The new DT1131i was the first jumbo sold to PNC in Norway,” says Åge Nesserstrand, Sandvik Mining and Rock Technology technical support representative for underground tunnelling. “In the beginning, along with the jumbo and 3D scanner, we delivered a package with the rock tools and a container with spare parts, so that they could be sure that production would continue uninterrupted. We also had a training package here for the operators on site.” The common rock here is gneiss and mica schist – old, solid rock, perfect for building tunnels. The Sandvik equipment can drill five-metre blasts at a time – quite a difference from the one- to two-metre blasts Hoerlein is used to in Central Europe.
“This is why the technology is so important here,” Hoerlein says. “In Austria and Germany, where you can only drill one metre at a time, you can’t go too far wrong with each blast. But here in Norway, if you drill by eye only, you can quickly end up a metre away from your planned track. You need technology to make accurate, fast progress.” PNC has been trialling Sandvik iSURE software, made possible by the jumbo’s onboard 3D scanning system. Marin Kulaš, the Geodata senior surveyor onsite contracted by PNC, has already seen the results of the new hardware and software first hand.
“The benefit of a 3D scanner is the possibility for immediate reaction, correction and speed of process – that’s the main thing,” he says. “It helps the operator see the contour, if there’s an underprofile or an overprofile, and he or she can react in place in real time. And the scan is like a fingerprint, so during the next round when the scanner makes a scan, it searches for identical points between the point cloud and the previous scan. Then you’re ready for the next round. The whole process of the navigation by scanner is under four minutes. That’s fast.” The technology Sandvik brings is a perfect fit for a new generation of engineers. “These ‘digital natives’ grew up with PlayStations and iPhones, and they have a great interest in the data and researching the new tools,” Hoerlein says. Education and automation are the future of the industry, he says, and with the data and the engineer working in tandem, they’re ready for an advanced level of safety, documentation and accuracy that clients expect. iSURE 3D reporting tools also make it easier to keep clients informed, increasing the trust between client and contractor. PNC believes in a transparent way of working, and this technology helps to make that process simple. “You deliver accurate information about the project in a straightforward way and then you can arrive at solutions together,” Hoerlein says. Hagspiel agrees: “We really like iSURE because we deliver a 3D model of our tunnel to the client,” she says. “With it we can show them where we have underprofile and overprofile and where we may have to drill new holes for reblasting.”
The Sandvik solution
For this tunnelling project, the first for PNC in Norway, Sandvik provided the new Sandvik DT1131i three-boom jumbo along with rock tools, drill bits and rods. Sandvik iSURE software and 3D scanner were trialled for the first time here in a project of this nature, offering high-level planning and analysis capabilities. Sandvik also supplied technical support and onsite training for operators at the site, working to ensure that the equipment, systems and support met the specific needs of the customer.
In this particular project, Hoerlein mentions that PNC has never had a problem with the stability of the machine and computer system – it has never crashed or failed during use, adding a level of accurate reliability. “It’s an absolutely stable system,” he says. It’s also possible to use the iSURE system to measure the exact position of the bolts, which in turn can be delivered to the client in 3D imaging, to a very high accuracy. “Otherwise, a surveyor has to measure tens of thousands of bolts and guess where the end sits in the mountain. This is one step into the future already.” Becoming integrated and part of the Norwegian tradition is important to PNC. The company is teaching Norwegian language to employees who are non-native speakers.
“It’s important to adopt the culture of the country,” Hoerlein says. PNC hopes to bring slab track rail as well as bridge and tunnel construction to Norway to assist with the country’s need for greater infrastructure, and to do it with Sandvik at its side. “Together with Sandvik, we test new products, like the 3D scanner, so that at later stages these products help to bring the tunnel business a step forward,” he says. “We don’t intend to finish this project and disappear. It’s an investment in the future of the country and the company together.”