Posted by: Jaring | September 21, 2009

Project Risks and Construction Aspects of Tunneling Through the Alps

Abstract

This paper presents a discussion about several construction aspects involved during construction of the Gotthard tunnel. The Gotthard tunnel project is one of the largest international project scale which links German and Italy through the Alps mountainous. The discussion mainly is emphasized on the project risks which influence the project design and its preparation. With such big scale of project, USD 7 billion project budget, 2,000 workers on the peak schedule, 57 kilometers tunnel length, and built under one of the highest mountainous in the world which probably has the hardest rock layer, the Gotthard tunnel has many risks that could affect to the project design and project preparation itself.


Keywords: Gotthard tunnel, project risks, project design and preparation.

Switzerland, with its location on the central of Europe, becomes the most important hub which links several important countries in the Europe. As a consequence, everyday there are many transportation modes run on the highway which cause heavy traffic jam. In addition, existing railways has already been congested with many train trips on them. Finally, the unusual decision has been taken for constructing new railway not over the Alps, but under the Alps. This project costs USD 7 billion and is expected to be completed in 2017. The most interested feature on this project is that the entire railway line is positioned at the same level (altitude) of 500 meters above mean sea level, this allows trains using the line to reach speed of 240 km per hour.

The most dangerous risk inside the tunnel is fire. When it appears then it will absorb oxygen more quickly than the people can do. Strong attention to this risk has been paid by the project’s stakeholders and several actions to prevent and mitigate the fire are being performed, both during the project construction and during the project operational period once it has been commissioned and tested. Huge several fans are installed for cooling down the temperature inside the tunnel; moreover, the fans are provided in the escape tunnel for supplying fresh air and pushing out smoke when there is a fire accident. All tools and equipments used in the project are inspected regularly for ensuring the safety of them during construction activities. In addition, design of concrete wall was also based on this risk; they provide fire proof concrete which was tested before the installation.

Train collision is one of the most likely accidents in the tunnel, particularly for a tunnel which comprises two railway directions. After considering several proposed designs, two tunnels with escape tunnels between them are selected. The Gotthard tunnel consists of two parallel tunnel; each 1,000 feet there are smaller perpendicular tunnels which link the parallel tunnels. This smaller tunnel will act as escape tunnel during the operational period.

The construction of Gotthard tunnel also will affect to the environmental condition. With improper approach it might result on negative environmental effects. In order to reduce the bad effect of stone debris, drilled or blasted rocks from the tunnel are recycled in the concrete factory located on each base camp. Result of this recycling activity is that the concretes are used for constructing side wall along the tunnel. Furthermore, own water treatment is also built so that water from construction will not contain poisonous materials when it is entering nearby rivers.

The most common risk in a project, of course, are exceed the time schedule and over budget. As this project has enormous scale, this kind of risk becomes considerably larger. To cope to this situation, the project is performed 24 hours a day and 365 days a year. Moreover, workers involved in this project are selected from the best people come from around the world. One of factors that affect the project schedule is work progress which is affected from productivity of equipments used in the project. The most important equipment on this project is tunnel boring machine (TBM). Design of this tool was performed carefully by doing some previous researches in Colorado for ensuring that the material used for the TBM and the force are sufficient for drilling the rocks with designated or specified rate. Furthermore, the drilling activities are not done from only one entrance in order to speed up the progress.

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Responses

  1. Hello, it really interesting, thanks


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