Stockholm City Line

Published 2010-01-28 10:49:54 | Updated 2010-01-28 11:08:44

The Stockholm City Line will be a 6 km double-track underground railway in the capital of Sweden. The project cost is the largest railway investment since the Stockholm Metro was built 60 years ago. Nitro Consult has been involved in the project since the beginning, with ground investigations, measurements of vibrations, noise and structure-borne sound, risk analyses and much more.

Currently under construction, the Stockholm City Line (Citybanan) is to be a 6 km double-track underground railway for commuter trains, which will double the current north-south rail track capacity through the city. The estimated project cost is SEK 16.8 billion (USD 2.4 billion), which is the largest investment in the railways of the Swedish capital since the Metro was built 60 years ago. Scheduled to open in 2017, the Stockholm City Line will run mostly through 130 m2 double-track rock tunnels, which fork into 2 x 80 m2 tunnels at station approaches. Altogether the project will require about 1.5 million m3 of rock to be excavated. The scheme includes a parallel service tunnel, two 260 m x 220 m2 under-city stations, two underwater concrete tunnels and a 1.5 km railway bridge.

Nitro Consult is a consultancy company specialized in blasting and rock engineering, vibration control and surveys. Nitro Consult has been involved in the Stockholm City Line project from the outset, starting with ground investigations. The company then participated in the design and drafting of construction documents for the rock-excavation work between the northern portal Tomteboda and the station Odenplan. Additionally, their Vibration Group has carried out a series of test blasts in order to determine the vibration limit-values for vulnerable buildings, such as the Gustav Vasa Church at Odenplan, and other sensitive installations. Nitro Consult has also performed risk analyses of the vibration-generating works along substantial lengths of the prospective tunnels.

In a joint venture with the company Ansvarsbesiktning AB, Nitro Consult is currently measuring vibrations, noise and structure-borne sound along the entire northern stretch of the main tunnels. Structural surveys of all buildings and other facilities within the risk zone shall also be carried out, before and after the vibration-generating works. The assignment includes the handling of all related questions and enquiries from neighbours and other third parties. Vibration measurements are taken on buildings, equipment and the underground railways. Approximately 100 measuring points are active daily. All measured values are reported to a server via GSM link. The client and contractors can read these measurements continuously via the Nitro Consult NCVIB Web portal. Every morning the contractors post the day’s scheduled blasting times in the NCVIB portal.

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Tags: Technical and blasting consulting, Rockand ground investigations