Marmaray’s first tube to be laid
Posted by meb at March 16th, 2007
The first tube of the $3 billion trans-Bosporus Marmaray railroad project, which will connect Asia and Europe, will soon be laid 60 meters below the surface of the strait, depending on weather conditions.
Minister of Transportation Binali Yıldırım said the tube-laying phase was one of the most critical steps of the project after drilling tunnels under the sea with TBN equipment, also known as “moles.”
Yıldırım said earlier this week at an exclusive meeting that the 41-meter-deep BART tunnel in San Francisco is known as the deepest undersea tunnel in the world but the Marmaray tunnel would sit at a depth of 60 meters. The project has attracted worldwide attention with its construction suited to the Bosporus’ unique features: The strait’s warm and cold waters are layered on top of each other and flow in opposite directions and the tube will be situated between the two. Yıldırım said that 2,770 piles within a 460-meter distance and had been filled with cement to increase the resistance of tunnels against earthquakes. The minister said the tubes will be 15.3 meters wide and 8.5 meters high, adding that the drilling of the trench in which the tubes will be laid had been completed, measuring 1,384 meters in length, 20 meters in width and 10-18 meters in height. The amount of sand excavated during the work amounted to 1.2 million cubic meters.
Eleven tubes of varying length — between 98.5 and 135 meters — will be sunk across the Bosporus, said Yıldırım. The No. 11 tube will be laid first, and the others will be sunk with one-and-a-half or two months. The minister said the process of laying the tubes would start in the evening and would be finished at noon the following day. The traffic on the strait will be halted for six hours at the beginning of the laying and two hours toward the end. The minister said the 64-kilometer-long suburban rails between Gebze — a province beyond Istanbul’s eastern border — and Halkalı — the westernmost district — and the 36 stations on the route would be upgraded within the framework of the project. He emphasized the tenders for trailers and passenger cars would be held on April.
Yıldırım pointed out that İstanbul’s traffic problems would be reduced significantly with the Marmaray project by integrating it with other railroads. He said that the continuous transfer of goods and passengers between Asia and Europe would become possible with the tunnels.
source: Today’s Zaman
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