The strait of Gibraltar is the gateway between the Atlantic Ocean and the Mediterranean Sea. The strait also separates the European and African continents by fourteen kilometres of water at its narrowest part, with depths reaching 900 meters at its deepest points.
The idea of a link between the two continents has been contemplated for some time now. However, due to the many challenges of such a project, it has not been attempted until now, when both the Spanish and Moroccan governments seem to be taking serious steps towards the achievement of this dream.
A Spanish minister once stated that the proposed tunnel will be “in the 21st century what the Suez Canal was in the 19th century and what the Panama Canal was in the 20th century.” The linking of the two so close yet so distant continents will mean closer ties, development of new communication and transportation links, and improved trade and cooperation between countries on the two sides of the strait.
Depending on the final shape and route of the tunnel, passengers may get the opportunity to travel from the Moroccan coast up to Madrid in four hours.
Initial estimates put the expected number of passengers to use the future tunnel at nine million annually, going up to eleven million passengers within ten years. Added to this is the moving of almost ten million tons of merchandise by train. The project is deemed necessary for both countries, given the strong trade ties between Spain and Morocco.
Many meetings have taken place to discuss the building of such a link. A number of alternative ways to establish the link were considered by a joint committee funded by the two governments.
Starting with the most obvious alternative of building a bridge, it was deemed unfeasible due to the depth of the waters which is at least 300 metres. The option of building a floating bridge was also found to also nonfeasible, given the large number of ships passing through the strait and because of the strong currents.
Other options, including building a prefabricated submersed tunnel, were found unfeasible because of the instability of the seabed.
Finally, more focus was brought to the project as options were narrowed down to digging a tunnel underneath the strait. Since a road tunnel posed major challenges regarding exhaust fumes, the only option that was deemed even close to being feasible was building a railway tunnel.
In 2003, a three-year study was undertaken to further investigate the feasibility of a proposed Gibraltar rail tunnel, similar to the Channel Tunnel between the United Kingdom and France.
Based on the recent studies, the project scope has become clearer. It will consist of a 40 kilometre stretch of twin rail tunnel with a service tunnel in between, similar to the Channel tunnel between England and France across the English Channel. However, this one, at three hundred meters depth, is six times deeper than its predecessor.
Two-thirds of the tunnel length will be one hundred to three hundred metres beneath the waters of the strait, while the other third will be used to gradually bring trains up to the surface on the two sides of the straits, at least three miles inland from the coast on both sides.
This is a challenging project for all involved from a technical, environmental, as well as a political point of view.
The Gibraltar Strait is known for its turbulent and rapid currents. Early studies of the waters and the seabed were hindered by these elements because ships could not remain stable to perform the necessary surveys of the seabed. To get over this hurdle, engineers had to find new methods of boring.
There are also major geological challenges facing the project, starting with the nature of the varying horizontal layers under the strait which means the tunnel will have to cross many different types of earth and rock. Adding to the complexity of the situation was the discovery of clay deposits by the Moroccan coast.
There have also been political tensions as well over the history of the relationship between Spain and Morocco. These tensions may affect the project progress or even inception. Disputes between the two countries are on a multitude of points including immigration, farming and the sovereignty of Septa and Melilla, which are under Spanish rule while lying on African soil. Other political challenges include concerns over the tunnel causing further complications to the existing immigration problems.
From the technical perspective, the project feasibility studies have been about weighing alternatives that are either very hard or even impossible to attain.
For example, while taking the shortest route across the straits means a much shorter tunnel, the depth of the water in that area at 900 meters makes the feat impossible.
Given all the technical, environmental, and political challenges, it will be a tough project to attempt, if it ever gets completed.
If the project construction is given the go ahead, it may begin as early as 2008 with the construction of the service tunnel attempted first. The project construction is expected to take fifteen years.
As far as the cost, there are no official estimates, but some put the cost estimate range between 5-10 billion euros. Some find these estimates too optimistic given that the Channel Tunnel actually cost ten billion euros and this one is expected to be more difficult and more costly.
The project is currently in its planning phase. Lombardi Engineering, a Swiss company was given the task of designing the tunnel in late 2006. Their preliminary studies should be done by 2008 and if all goes well, actual construction may also begin in 2008. It is expected that work will start on the service tunnel first, then the twin rail tunnels.
Tuesday, February 13, 2007