After more than 25 years of arduous tunnelling, construction workers have finally holed through on Russia’s longest rail tunnel, the 15km long Severomuisk tunnel, east of Lake Baikal in south eastern Siberia, about 4,320km from Moscow.
Construction of the $2.5bn tunnel started in 1976 and, at its peak, Russian construction company Bamtonnelstroi employed 10,000 workers on the project along the Baikal-Amur railway.
The crossing under the Severomuisk mountain range was the most challenging part of the rail route. The contracting organisations were equipped with state of the art machinery, including gantry type drill rigs, powerful loaders, heavy-load haulage vehicles, travelling formworks and Robbins (4.5m dia) and Wirth (5.5m dia) TBMs. The TBMs were used to excavate different lengths of the parallel pilot tunnel in advance of the main drill and blast single track tunnel. The tunnellers set records at even the hardest times. One team managed to advance 170m/month when the target was 75m. In October 1985, another 5m were added to beat the record.
However, the tunnel advance lagged behind the construction schedule due to the extremely poor ground conditions that included four severely faulted zones requiring forepoling, vertical and horizontal dewatering and chemical grouting. To add to this, the collapse of the Soviet Union cause major funding problems for the project. These were eliminated in 1997, when the Russian Railway Ministry secured funding to complete the tunnel project in the shortest possible time.
The breakthrough having been made, the last construction phase will comprise the permanent lining installation, waterproofing and track laying. Commissioning of the tunnel is planned for the end of 2002.
