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role="navigation"> <ul itemscope itemtype="https://schema.org/BreadcrumbList" class="breadcrumb"> <li class="active"> <span class="divider icon-location"></span> </li> <li itemprop="itemListElement" itemscope itemtype="https://schema.org/ListItem"> <a itemprop="item" href="/en/why-go-underground" class="pathway"><span itemprop="name">Why go underground</span></a> <span class="divider"> > </span> <meta itemprop="position" content="1"> </li> <li itemprop="itemListElement" itemscope itemtype="https://schema.org/ListItem"> <span itemprop="name"> Environmental Reasons </span> <meta itemprop="position" content="2"> </li> </ul> </div> </div> <div class="clearfix item-page" itemscope itemtype="https://schema.org/Article"> <meta itemprop="inLanguage" content="en-GB" /> <div class="page-header"> <h1> Topographic reasons </h1> </div> <ul class="pager pagenav"> <li class="previous"> <a class="hasTooltip" title="Environmental preservation" aria-label="Previous article: Environmental preservation" href="/en/why-go-underground/environmental-reasons/environmental-preservation" rel="prev"> <span class="icon-chevron-left" aria-hidden="true"></span> <span aria-hidden="true"></span> </a> </li> </ul> <div itemprop="articleBody"><a href="/en/why-go-underground/environmental-reasons/topographic-reasons?tmpl=component&format=pdf" onclick="window.open(this.href,'win2','status=no,toolbar=no,scrollbars=yes,titlebar=no,menubar=no,resizable=yes,width=640,height=480,directories=no,location=no'); return false;" title="PDF" rel="nofollow" class="pdfButton"><img src="/templates/about-tunnelling/images/system/pdf_button.png"></a> <a target="_blank" title="Opens external link in new window" href="http://www.nccnet.co.jp/english/introduction/tokyobay.html"> <img class="imgLeft" src="/images/visuels/public/1_why/1_environmental/4_topographic_1.jpg" alt="" /> </a> <p>In hilly or mountainous areas, the use of <span class="mytool"><abbr title="A tunnel, strictly speaking, is a subterranean passage open at both ends. Often used as a synonym for adit, drift or gallery">tunnels</abbr></span> improves or makes feasible various transport options such as roads, railways, canals, etc. This is especially true when it comes to the construction of high speed transportation lines, as low <span class="mytool"><abbr title="Maximum price that would be paid to obtain a good. It is generally a function of the quantity of this good already possessed or already consumed">values</abbr></span> of steepness and radius are needed. Tunnels are also an important option in river, straits and harbour crossings, becoming on some occasions the only possibility to cross water expanses (high currents, large depths, large maritime <span class="mytool"><abbr title="Coming or going of persons or goods">traffic</abbr></span>, etc).</p> <p>Therefore, the layout of <span class="mytool"><abbr title="Below ground level">underground</abbr></span> facilities and <span class="mytool"><abbr title="Defined as an 'underlying foundation or basic framework'. Has come to mean a diverse collection of constructed facilities and associated services that support industry, commerce and everyday living">infrastructures</abbr></span> <span class="mytool"><abbr title="An issue that is considered of value. Often used interchangeably with advantage">benefits</abbr></span> from several <span class="mytool"><abbr title="An issue that is considered of value. Only those issues that represent differences among alternatives may be considered in an analysis.">advantages</abbr></span>. These advantages derive essentially from the freedom (within geological, cost, and land ownership limitations) to plan a facility in three dimensions and from the removal of physical barriers on the land. These advantages are essential when planning infrastructure in very dense urban <span class="mytool"><abbr title="A general term used to describe the form and quality of the surroundings for a person or place. Usually has a strong connotation for the natural aspects of the surroundings">environments</abbr></span>, where there is a big lack of space available and multiple geographical constraints.</p> <br /> <a target="_blank" title="Opens external link in new window" href="http://www.alptransit.ch/en/project-alptransit-gotthard/the-new-gotthard-rail-link/"> <img class="imgRight" src="/images/visuels/public/1_why/1_environmental/4_topographic_2.jpg" alt="" /> </a> <p>Some basic examples of situations where topographic reasons oblige the construction of underground infrastructures as the only possible solution are the transalpine rail tunnels crossing Switzerland.</p> <p>Both Gotthard and Lotschberg tunnels (with 57 and 34 km respectively) must cross mountains of several thousands of meters maintaining at the same time very limited values of radius and steepness to allow for high speed train circulation of up to 250 km/h.</p> <h3>Links & images</h3> <ul> <li><a target="_blank" title="Opens external link in new window" href="http://www.nccnet.co.jp/english/introduction/tokyobay.html">Trans-Tokio Bay Highway</a> (top)</li> <li><a target="_blank" title="Opens external link in new window" href="http://www.alptransit.ch/en/project-alptransit-gotthard/the-new-gotthard-rail-link/">Gotthard Base Tunnel</a> (right)</li> </ul> </div> </div>  </main> </div>  <script src="https://www.ita-aites.org/Common/sponsors.js?1732390269"></script> </div> </div>  <link rel="stylesheet" href="https://www.ita-aites.org/Common/footer.css?1732390269" type="text/css" /> <script src="https://www.ita-aites.org/Common/footer.js?1732390269"></script> </body> </html>