The challenging construction work of the new, westbound metro line in Helsinki demands wide-ranging expertise. Drilling maintenance shafts for metro tunnels has little room for error, but Kalliorakennus-Yhtiöt ensured a successful end result by using Robit products.
The metro tunnel shafts are a vital part of the underground railway system. They serve as emergency exits, smoke vents and pressure equalization as well as ventilation systems. Among their other large contributions to the West Metro construction, Kalliorakennus-Yhtiöt had to drill 44 meter-deep shafts with a surface area of 68 square meters to solid Scandinavian bedrock – by no means a trivial task.
“We set tough quality requirements for the project, as the work outcome must be exact. We drilled the excavation holes for the shaft from the top right down to the bottom, whereas drilling is normally carried out from both the bottom and the top. It was crucial that the holes turned out straight,” explains site manager Martti Kähkönen from Kalliorakennus. “We used Robit Rocktools special equipment to make sure the drilling holes were straight”.
The collaboration between Kalliorakennus and Robit go back since the early ‘90s. “All of the bits we use are from Robit, because they are familiar products for me. I participated in the bit development work for the first time many years ago”, Kähkönen recalls. In addition to the shared history, Robit’s wide service offering has also impressed Kalliorakennus. “Robit is a reliable partner, but their bit-sharpening service was also a major reason behind why we chose them as co-operation partner in the West Metro project,” he says.