Issue link: http://read.dmtmag.com/i/653001
I DA U N I V E R S A L M a rc h -A p r i l 2 0 1 6 22 2011, it is being driven in two main contracts. e largest is by contractor Strabag and joint venture partner Jägerbau with 20km to do. A fi rst section of around 3km was in so ground, while the rest is parallel hard rock drives – one of 16km and one 17m, both with segmental linings. Begun two years ago, these have proved slow going in hard and o en blocky rock, though the contractor is pleased with its two "tough" CREG-Wirth TBMs now over 11km in. e client, Austria's Federal Railways civil engineering company ÖBB Infrastruktur, has said that progress is within the param- eters of the contract for the eventual 2018 completion. e remaining approxi- mately 12km of tunnel was let last year to Porr, and is being driven by conventional methods in one tube, where half was excavated in the investigation stage, and by a multimode Herrenknecht TBM on the full length of the other bore. North of Graz, meanwhile, the 27km long Semmering is just starting. Cutting under the historic but speed- and gradient-limited Semmering mountain railway, it will also provide a fl at gradient for high-speed trains. Because of exceptionally complex geology and high water heads investigated in detail over the last decade, the tunnel is divided into several sections, mostly to be built by conventional means. Contracts are currently being let. Only one central section of 9km can be done by TBM, starting from a cavern at the base of a 400m deep sha Tunnel continued from page 21