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76-581: The 5.4 km (3.4 mi) double-deck tunnel connects Kumkapı on the European part and Koşuyolu, Kadıköy , on the Anatolian part of Istanbul with a 14.6 km (9.1 mi) route including the tunnel approach roads. It crosses the Bosphorus beneath the seabed at a maximum depth of −106 m (348 ft). It is about 1 km (0.62 mi) south of the undersea railway tunnel Marmaray , which

152-695: A canal . The central portions of a rapid transit network are usually in the tunnel. Some tunnels are used as sewers or aqueducts to supply water for consumption or for hydroelectric stations. Utility tunnels are used for routing steam, chilled water, electrical power or telecommunication cables, as well as connecting buildings for convenient passage of people and equipment. Secret tunnels are built for military purposes, or by civilians for smuggling of weapons , contraband , or people . Special tunnels, such as wildlife crossings , are built to allow wildlife to cross human-made barriers safely. Tunnels can be connected together in tunnel networks . A tunnel

228-453: A 1.4 m/d (4.6 ft/d)/face advance rate under a densely populated district with minimum and maximum overburden of 8 and 41 m (26 and 135 ft), respectively. Both tunnels met up each other within ±2 mm (0.079 in) tolerance. The largest converge measured at the tunnel crown was 33 mm (1.30 in) (design tolerance is 50 mm or 1.97 in) with a maximum 10 mm (0.39 in) surface settlement. The tunnel

304-449: A large factor in the decision making process. Civil engineers usually use project management techniques for developing a major structure. Understanding the amount of time the project requires, and the amount of labor and materials needed is a crucial part of project planning. The project duration must be identified using a work breakdown structure and critical path method . Also, the land needed for excavation and construction staging, and

380-467: A pipe jack, with the span of some box jacks in excess of 20 metres (66 ft). A cutting head is normally used at the front of the box being jacked, and spoil removal is normally by excavator from within the box. Recent developments of the Jacked Arch and Jacked deck have enabled longer and larger structures to be installed to close accuracy. There are also several approaches to underwater tunnels,

456-527: A service life against subsea conditions. Only 0.3% of produced segments were found to be deficient due to existence of cracks width more than 0.2 mm (0.008 in). On the other hand, twin tunnels (each has approximately 950 m or 3,120 ft length) were completed in 445 calendar days with a cross section of 85 m (910 sq ft) each by classical mining method. These tunnels were excavated in Trakya Formation from four faces with

532-532: A shoreline road beside the Sea of Marmara . Widening of the entire Segment 1, which is approximately 5.4 km (3.4 mi), from 3x2 lanes to 2x4 lanes. Construction of a 5.4 km (3.4 mi), two-deck road tunnel with two lanes on each deck, a toll plaza and an administrative building on the western end and ventilation shafts on both ends of the tunnel. Widening from 2x3 and 2x4 lanes to 2x4 and 2x5 lanes along an approximately 3.8 km (2.4 mi) stretch of

608-421: A specialized method called clay-kicking for digging tunnels in clay-based soils. The clay-kicker lies on a plank at a 45-degree angle away from the working face and rather than a mattock with his hands, inserts with his feet a tool with a cup-like rounded end, then turns the tool with his hands to extract a section of soil, which is then placed on the waste extract. Clay-kicking is a specialized method developed in

684-712: A storm on the Propontis brought the Argonauts back to an island they had left, precipitating a battle in which either Jason or Heracles killed King Cyzicus , who had mistaken them for his Pelasgian enemies. The International Hydrographic Organization defines the limits of the Sea of Marmara as follows: On the West . The Dardanelles limit of the Aegean Sea [A line joining Kum Kale (26°11'E) and Cape Helles ]. On

760-434: A tube can be sunk into a body of water, which is called an immersed tunnel. Cut-and-cover is a simple method of construction for shallow tunnels where a trench is excavated and roofed over with an overhead support system strong enough to carry the load of what is to be built above the tunnel. There are two basic forms of cut-and-cover tunnelling: Shallow tunnels are often of the cut-and-cover type (if under water, of

836-747: A tunnel than a sufficiently strong bridge). Some water crossings are a mixture of bridges and tunnels, such as the Denmark to Sweden link and the Chesapeake Bay Bridge-Tunnel in Virginia . There are particular hazards with tunnels, especially from vehicle fires when combustion gases can asphyxiate users, as happened at the Gotthard Road Tunnel in Switzerland in 2001. One of the worst railway disasters ever,

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912-432: A tunnel. Bridges usually require a larger footprint on each shore than tunnels. In areas with expensive real estate, such as Manhattan and urban Hong Kong , this is a strong factor in favor of a tunnel. Boston's Big Dig project replaced elevated roadways with a tunnel system to increase traffic capacity, hide traffic, reclaim land, redecorate, and reunite the city with the waterfront. The 1934 Queensway Tunnel under

988-495: Is allowed in this tunnel tube, and motorcyclists are directed to the other tube. Each level was built with a three-lane roadway, but only two lanes per level are used – the third serves as a hard shoulder within the tunnel. The A86 Duplex is Europe's longest double-deck tunnel. Sea of Marmara The Sea of Marmara , also known as the Sea of Marmora or the Marmara Sea , is a small inland sea located entirely within

1064-547: Is an underground or undersea passageway. It is dug through surrounding soil, earth or rock, or laid under water, and is usually completely enclosed except for the two portals common at each end, though there may be access and ventilation openings at various points along the length. A pipeline differs significantly from a tunnel, though some recent tunnels have used immersed tube construction techniques rather than traditional tunnel boring methods. A tunnel may be for foot or vehicular road traffic , for rail traffic, or for

1140-555: Is constructed by the New Austrian Tunnelling method (NATM) and cut-and-cover method. The tunnel's excavation diameter is 13.7 m (45 ft), which allows an inner diameter of 12.0 m (39.4 ft) with 60 cm (23.6 in)-thick lining. The tunnel alignment is located in a seismically active region, about 17 km (11 mi) to the North Anatolian Fault Zone. To decrease

1216-402: Is designed so that it has protected emergency areas every 200 m (220 yd) to provide shelter, also escape routes to the other tunnel level. Every 600 m (660 yd) there will be an emergency lane equipped with emergency telephone. The speed limit in the tunnel route 70 km/h (43 mph). A daily average of around 120,000 cars and light vehicles was expected to pass through

1292-505: Is intended to carry both the Istanbul metro and a two-level highway, over a length of 6.5 km (4.0 miles). The French A86 Duplex Tunnel  [ fr ] in west Paris consists of two bored tunnel tubes, the eastern one of which has two levels for light motorized vehicles, over a length of 10 km (6.2 miles). Although each level offers a physical height of 2.54 m (8.3 ft), only traffic up to 2 m (6.6 ft) tall

1368-673: Is privately owned by the Koç family of industrialists. The North Anatolian Fault runs under the sea and has triggered several major earthquakes , such as those in Izmit and Düzce in August and November 1999 respectively. The August 1999 earthquake is commonly referred to as the Marmara Earthquake since its epicentre lay under the Sea and most of the places worst affected by the quake and ensuing tsunami lay along its shores. During

1444-494: Is relatively long and narrow; the length is often much greater than twice the diameter , although similar shorter excavations can be constructed, such as cross passages between tunnels. The definition of what constitutes a tunnel can vary widely from source to source. For example, in the United Kingdom, a road tunnel is defined as "a subsurface highway structure enclosed for a length of 150 metres (490 ft) or more." In

1520-665: Is slightly more than that of the Black Sea , but only about two-thirds that of most oceans . The water is much more saline at the bottom of the sea, averaging a salinity of around 38 parts per thousand, similar to that of the Mediterranean Sea . This high-density saline water does not migrate to the surface as is also the case with the Black Sea. Water from the Susurluk , Biga (Granicus), and Gönen Rivers also reduces

1596-401: Is sometimes necessary during the excavation of a tunnel. They are usually circular and go straight down until they reach the level at which the tunnel is going to be built. A shaft normally has concrete walls and is usually built to be permanent. Once the access shafts are complete, TBMs are lowered to the bottom and excavation can start. Shafts are the main entrance in and out of the tunnel until

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1672-515: Is that the open building pit is muted after tunnel construction; no roof is placed. Some tunnels are double-deck, for example, the two major segments of the San Francisco–Oakland Bay Bridge (completed in 1936) are linked by a 160-metre (540 ft) double-deck tunnel section through Yerba Buena Island , the largest-diameter bored tunnel in the world. At construction this was a combination bidirectional rail and truck pathway on

1748-698: Is the Siloam Tunnel , built in Jerusalem by the kings of Judah around the 8th century BC. Another tunnel excavated from both ends, maybe the second known, is the Tunnel of Eupalinos , which is a tunnel aqueduct 1,036 m (3,400 ft) long running through Mount Kastro in Samos , Greece. It was built in the 6th century BC to serve as an aqueduct . In Ethiopia , the Siqurto foot tunnel , hand-hewn in

1824-569: The Balvano train disaster , was caused by a train stalling in the Armi tunnel in Italy in 1944, killing 426 passengers. Designers try to reduce these risks by installing emergency ventilation systems or isolated emergency escape tunnels parallel to the main passage. Government funds are often required for the creation of tunnels. When a tunnel is being planned or constructed, economics and politics play

1900-674: The European Investment Bank (EIB) and financing and guarantees from Export-Import Bank of Korea and K-Sure, also with participation from Sumitomo Mitsui Banking Corporation , Standard Chartered , Mizuho Bank , Türkiye İş Bankası , Garanti Bank and Yapı ve Kredi Bankası . A hedging facility for the transaction is provided by some of the lenders as well as Deutsche Bank . The project consists of three main segments: Construction of five U-turns as underpasses and seven pedestrian crossings as overpasses along Kennedy Street that stretches between Kazlıçeşme and Sarayburnu as

1976-471: The Port Authority of New York and New Jersey was not aware of this bill and had not asked for a grant for such a project. Increased taxes to finance a large project may cause opposition. Tunnels are dug in types of materials varying from soft clay to hard rock. The method of tunnel construction depends on such factors as the ground conditions, the groundwater conditions, the length and diameter of

2052-848: The Queens-Midtown Tunnel between Manhattan and the borough of Queens on Long Island ; the Detroit-Windsor Tunnel between Michigan and Ontario ; and the Elizabeth River tunnels between Norfolk and Portsmouth, Virginia ; the 1934 River Mersey road Queensway Tunnel ; the Western Scheldt Tunnel , Zeeland, Netherlands; and the North Shore Connector tunnel in Pittsburgh, Pennsylvania . The Sydney Harbour Tunnel

2128-472: The River Mersey at Liverpool was chosen over a massively high bridge partly for defense reasons; it was feared that aircraft could destroy a bridge in times of war, not merely impairing road traffic but blocking the river to navigation. Maintenance costs of a massive bridge to allow the world's largest ships to navigate under were considered higher than for a tunnel. Similar conclusions were reached for

2204-679: The United Kingdom of digging tunnels in strong clay-based soil structures. This method of cut and cover construction required relatively little disturbance of property during the renewal of the United Kingdom's then ancient sewerage systems. It was also used during the First World War by Royal Engineer tunnelling companies placing mines beneath German lines, because it was almost silent and so not susceptible to listening methods of detection. Tunnel boring machines (TBMs) and associated back-up systems are used to highly automate

2280-610: The canton of Glarus . The borehole has a diameter of 8.03 metres (26.3 ft). The four TBMs used for excavating the 57-kilometre (35 mi) Gotthard Base Tunnel , in Switzerland , had a diameter of about 9 metres (30 ft). A larger TBM was built to bore the Green Heart Tunnel (Dutch: Tunnel Groene Hart) as part of the HSL-Zuid in the Netherlands, with a diameter of 14.87 metres (48.8 ft). This in turn

2356-489: The water table . This pressurizes the ground ahead of the TBM cutter head to balance the water pressure. The operators work in normal air pressure behind the pressurized compartment, but may occasionally have to enter that compartment to renew or repair the cutters. This requires special precautions, such as local ground treatment or halting the TBM at a position free from water. Despite these difficulties, TBMs are now preferred over

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2432-689: The 16th century as a metaphor for a narrow, confined space like the inside of a cask. Some of the earliest tunnels used by humans were paleoburrows excavated by prehistoric mammals. Much of the early technology of tunneling evolved from mining and military engineering . The etymology of the terms "mining" (for mineral extraction or for siege attacks ), " military engineering ", and " civil engineering " reveals these deep historic connections. Predecessors of modern tunnels were adits that transported water for irrigation , drinking, or sewerage . The first qanats are known from before 2000 BC. The earliest tunnel known to have been excavated from both ends

2508-638: The 1960s. The main idea of this method is to use the geological stress of the surrounding rock mass to stabilize the tunnel, by allowing a measured relaxation and stress reassignment into the surrounding rock to prevent full loads becoming imposed on the supports. Based on geotechnical measurements, an optimal cross section is computed. The excavation is protected by a layer of sprayed concrete, commonly referred to as shotcrete . Other support measures can include steel arches, rock bolts, and mesh. Technological developments in sprayed concrete technology have resulted in steel and polypropylene fibers being added to

2584-716: The 1971 Kingsway Tunnel under the Mersey. In Hampton Roads, Virginia , tunnels were chosen over bridges for strategic considerations; in the event of damage, bridges might prevent US Navy vessels from leaving Naval Station Norfolk . Water-crossing tunnels built instead of bridges include the Seikan Tunnel in Japan; the Holland Tunnel and Lincoln Tunnel between New Jersey and Manhattan in New York City ;

2660-479: The European and Asian shores of İstanbul and the entire archipelago forms part of the conurbation. To the south lie the Marmara Islands , an archipelago made up of the eponymous Marmara Island and three other inhabited islands – Avşa , Paşalimanı and Ekinlik – as well as of seventeen largely uninhabited islands including the prison island of Imralı whose most famous prisoner, since 1999, has been

2736-709: The Middle Ages, crosses a mountain ridge. In the Gaza Strip , the network of tunnels was used by Jewish strategists as rock-cut shelters, in first links to Judean resistance against Roman rule in the Bar Kokhba revolt during the 2nd century AD. A major tunnel project must start with a comprehensive investigation of ground conditions by collecting samples from boreholes and by other geophysical techniques. An informed choice can then be made of machinery and methods for excavation and ground support, which will reduce

2812-592: The Northeast . A line joining Cape Rumili with Cape Anatoli (41°13′N). The sea's south coast is heavily indented and includes the Gulf of İzmit ( Turkish : İzmit Körfezi ), the Gulf of Gemlik ( Turkish : Gemlik Körfezi ), the Gulf of Bandırma ( Turkish : Bandırma Körfezi ), and the Gulf of Erdek ( Turkish : Erdek Körfezi ). The surface salinity of the Marmara averages about 22 parts per thousand, which

2888-484: The Ottoman imperial government", consisting of a submerged bridge supporting a tube where steam trains would run. The conceptual background of Eurasia Tunnel reaches back to the findings of the 1997 Transportation Master Plan undertaken by Istanbul University on behalf of Istanbul Metropolitan Municipality . Based on this plan, a pre-feasibility study had been conducted in 2003 for a new Bosphorus crossing. According to

2964-596: The PKK leader Abdullah Öcalan . These islands lie within Balıkesir province and are most readily accessible from Tekirdağ in Thrace or Erdek on the southern shore of the Sea of Marmara. In high summer additional ferries travel to Avşa and Marmara Islands from the centre of İstanbul to facilitate a growing tourist trade. There are also a few individual islands elsewhere in the Sea of Marmara, such as Koç Adası, off Tuzla , which

3040-599: The United States, the NFPA definition of a tunnel is "An underground structure with a design length greater than 23 m (75 ft) and a diameter greater than 1,800 millimetres (5.9 ft)." The word "tunnel" comes from the Middle English tonnelle , meaning "a net", derived from Old French tonnel , a diminutive of tonne ("cask"). The modern meaning, referring to an underground passageway, evolved in

3116-459: The bentonite slurry used during excavation and regenerates with 2,800 m/h (99,000 cu ft/h) capacity (approximately equivalent to 20 m/d or 66 ft/d) was installed. The utilized TBM ranks first in the world with its 33 kW/m (4.1 hp/sq ft) cutterhead power, second with its 12.0 bar (1.20 MPa; 174 psi) pressure design; and sixth with its 147 m (1,580 sq ft) excavation area. TBM operation

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3192-400: The blocky nature of rocks, the exact location of fault zones, or the stand-up times of softer ground. This may be a particular concern in large-diameter tunnels. To give more information, a pilot tunnel (or "drift tunnel") may be driven ahead of the main excavation. This smaller tunnel is less likely to collapse catastrophically should unexpected conditions be met, and it can be incorporated into

3268-457: The borders of Turkey . It connects the Black Sea to the Aegean Sea via the Bosporus and Dardanelles straits, separating Turkey’s European and Asian sides. It has an area of 11,350 km (4,380 sq mi), and its dimensions are 280 km × 80 km (174 mi × 50 mi). Its greatest depth is 1,370 m (4,490 ft). The Sea of Marmara is named after

3344-502: The concrete mix to improve lining strength. This creates a natural load-bearing ring, which minimizes the rock's deformation . By special monitoring the NATM method is flexible, even at surprising changes of the geomechanical rock consistency during the tunneling work. The measured rock properties lead to appropriate tools for tunnel strengthening . In pipe jacking , hydraulic jacks are used to push specially made pipes through

3420-495: The current D100 road that links at Göztepe to Ankara-İstanbul State Highway, and construction of 2 bridge intersections, 1 overpass and 3 pedestrian bridges. The American firm Parsons Brinckerhoff was responsible for the design, while the British Arup Group and American Jacobs Engineering Group undertook the technical and traffic studies and HNTB provided independent design verification. The geotechnical survey

3496-409: The entire tunnelling process, reducing tunnelling costs. In certain predominantly urban applications, tunnel boring is viewed as a quick and cost-effective alternative to laying surface rails and roads. Expensive compulsory purchase of buildings and land, with potentially lengthy planning inquiries, is eliminated. Disadvantages of TBMs arise from their usually large size – the difficulty of transporting

3572-521: The feasibility study also support the selection of the proposed route in terms of environmental and social costs and risk factors. Avrasya Tüneli İşletme İnşaat ve Yatırım A.Ş. (ATAŞ) was founded on 26 October 2009 by the partnership of Yapı Merkezi from Turkey and SK E&C from South Korea. The build–operate–transfer model adopted at the Eurasia Tunnel, has brought together the private investment dynamism and their project experience, and

3648-441: The final tunnel or used as a backup or emergency escape passage. Alternatively, horizontal boreholes may sometimes be drilled ahead of the advancing tunnel face. Other key geotechnical factors: For water crossings, a tunnel is generally more costly to construct than a bridge. However, both navigational and traffic considerations may limit the use of high bridges or drawbridges intersecting with shipping channels, necessitating

3724-405: The ground behind a TBM or shield. This method is commonly used to create tunnels under existing structures, such as roads or railways. Tunnels constructed by pipe jacking are normally small diameter bores with a maximum size of around 3.2 metres (10 ft). Box jacking is similar to pipe jacking, but instead of jacking tubes, a box-shaped tunnel is used. Jacked boxes can be a much larger span than

3800-640: The immersed-tube type), while deep tunnels are excavated, often using a tunnelling shield . For intermediate levels, both methods are possible. Large cut-and-cover boxes are often used for underground metro stations, such as Canary Wharf tube station in London. This construction form generally has two levels, which allows economical arrangements for ticket hall, station platforms, passenger access and emergency egress, ventilation and smoke control, staff rooms, and equipment rooms. The interior of Canary Wharf station has been likened to an underground cathedral, owing to

3876-435: The inevitable smoke and steam. A major disadvantage of cut-and-cover is the widespread disruption generated at the surface level during construction. This, and the availability of electric traction, brought about London Underground's switch to bored tunnels at a deeper level towards the end of the 19th century. Prior to the replacement of manual excavation by the use of boring machines, Victorian tunnel excavators developed

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3952-582: The initially proposed route as the preferred option. The three current bridges across the Bosphorus were taken into consideration in selecting the tunnel's location, which was put farther south to better balance the distribution of traffic between the crossings. Other selection criteria included the route's lower investment cost due to a shorter tunnel length and the availability of sufficient space for construction sites and operational buildings (toll plaza, administrative units). High level assessments based on corridor alternatives that are comprehensively defined in

4028-468: The large TBM to the site of tunnel construction, or (alternatively) the high cost of assembling the TBM on-site, often within the confines of the tunnel being constructed. There are a variety of TBM designs that can operate in a variety of conditions, from hard rock to soft water-bearing ground. Some TBMs, the bentonite slurry and earth-pressure balance types, have pressurized compartments at the front end, allowing them to be used in difficult conditions below

4104-572: The largest island on its south side, called Marmara Island because it is rich in marble ( Greek μάρμᾰρον , mármaron 'marble'). In classical antiquity , it was known as the Propontis , from the Greek words pro 'before' and pontos 'sea', reflecting the fact that the Ancient Greeks used to sail through it to reach the Black Sea , which they called Pontos . In Greek mythology ,

4180-401: The latest 19 in (483 mm)} disc cutters (35 pieces monoblock disc cutters, all atmospherically changeable and have individual wearing sensor system), 192 piece cutting knives (only 48 atmospherically changeable), special pressurized locks for divers and material and rescue chamber for all shift members. Slurry Treatment Plant (installed power of 3.5 MW or 4,700 hp which de-silts

4256-629: The lower deck with automobiles above, now converted to one-way road vehicle traffic on each deck. In Turkey, the Eurasia Tunnel under the Bosphorus , opened in 2016, has at its core a 5.4 km (3.4 miles) two-deck road tunnel with two lanes on each deck. Additionally, in 2015 the Turkish government announced that it will build three -level tunnel, also under the Bosporus. The tunnel

4332-483: The older method of tunnelling in compressed air, with an airlock/decompression chamber some way back from the TBM, which required operators to work in high pressure and go through decompression procedures at the end of their shifts, much like deep-sea divers . In February 2010, Aker Wirth delivered a TBM to Switzerland, for the expansion of the Linth–Limmern Power Stations located south of Linthal in

4408-540: The operation of empty and loaded trains at the same time. The temporary way is replaced by the permanent way at completion, thus explaining the term " Perway ". The vehicles or traffic using a tunnel can outgrow it, requiring replacement or enlargement: An open building pit consists of a horizontal and a vertical boundary that keeps groundwater and soil out of the pit. There are several potential alternatives and combinations for (horizontal and vertical) building pit boundaries. The most important difference with cut-and-cover

4484-522: The project is completed. If a tunnel is going to be long, multiple shafts at various locations may be bored so that entrance to the tunnel is closer to the unexcavated area. Once construction is complete, construction access shafts are often used as ventilation shafts , and may also be used as emergency exits. The New Austrian Tunnelling method (NATM)—also referred to as the Sequential Excavation Method (SEM) —was developed in

4560-490: The proper machinery must be selected. Large infrastructure projects require millions or even billions of dollars, involving long-term financing, usually through issuance of bonds . The costs and benefits for an infrastructure such as a tunnel must be identified. Political disputes can occur, as in 2005 when the US House of Representatives approved a $ 100 million federal grant to build a tunnel under New York Harbor. However,

4636-416: The results of this study, a road tunnel was recommended as the solution that offered the highest degree of feasibility. The Ministry of Transportation, Maritime and Communication of Turkey commissioned a feasibility study by Nippon Koei Co. Ltd. in 2005 to assess route alternatives for a new tunnel crossing. Based on environmental and social criteria, cost and risk factors, the study concluded by supporting

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4712-482: The risk of encountering unforeseen ground conditions. In planning the route, the horizontal and vertical alignments can be selected to make use of the best ground and water conditions. It is common practice to locate a tunnel deeper than otherwise would be required, in order to excavate through solid rock or other material that is easier to support during construction. Conventional desk and preliminary site studies may yield insufficient information to assess such factors as

4788-609: The salinity of the sea, though with less effect than on the Black Sea. With little land in Thrace draining southward, almost all of these rivers flow from Anatolia . There are two main groups of islands in the Sea of Marmara. To the north lie the Princes' Islands , an archipelago made up of the inhabited islands of Kınaliada , Burgazada , Heybeliada , Büyükada and Sedef Adası and several uninhabited islands including Sivriada , Yassıada , Kaşıkadası and Tavşanadası . The inhabited islands are readily accessible by ferry from both

4864-452: The seismic stresses/strains below the permissible levels, two flexible seismic joints/segments; with displacement limits of ±50 mm (1.97 in) for shear and ±75 mm (2.95 in) for extraction/contraction; were innovated, designed specially, localized through geological/geophysical/geotechnical conditions, tested in laboratory; implemented 'first time' in TBM tunnelling under similar severe conditions. The design earthquake magnitude

4940-542: The sheer size of the excavation. This contrasts with many traditional stations on London Underground , where bored tunnels were used for stations and passenger access. Nevertheless, the original parts of the London Underground network, the Metropolitan and District Railways, were constructed using cut-and-cover. These lines pre-dated electric traction and the proximity to the surface was useful to ventilate

5016-459: The support of international financial institutions. The concession lasts 29 years. Partnership contract includes guaranteed minimum revenue and profit sharing for parts exceeding guaranteed revenue. The European Bank for Reconstruction and Development (EBRD) is supplying a finance package worth US$ 150 million. Other components of the US$ 1.245 billion financing package include a $ 350 million loan from

5092-553: The tunnel after the first year, previous to it's inauguration. As of September 2022, the record set for daily vehicles transit was set on September 8 that year, counting up to 67,982 vehicles in a single day, still far from expectations, but being consider a proof of its success. The toll is planned to be Turkish lira equivalent of US$ 4 plus VAT for cars and US$ 6 plus VAT for minibuses in each direction. The toll rate will change in accordance with US Consumer Price Index . Tunnel#Double-deck and multipurpose tunnels A tunnel

5168-400: The tunnel drive, the depth of the tunnel, the logistics of supporting the tunnel excavation, the final use and the shape of the tunnel and appropriate risk management. There are three basic types of tunnel construction in common use. Cut-and-cover tunnels are constructed in a shallow trench and then covered over. Bored tunnels are constructed in situ, without removing the ground above. Finally,

5244-428: The two most common being bored tunnels or immersed tubes , examples are Bjørvika Tunnel and Marmaray . Submerged floating tunnels are a novel approach under consideration; however, no such tunnels have been constructed to date. During construction of a tunnel it is often convenient to install a temporary railway, particularly to remove excavated spoil , often narrow gauge so that it can be double track to allow

5320-435: The world) were successfully performed. 15,048 piece 600 mm (23.62 in)-thick precast segments (1,672 rings) with the high performance (average charge passed is 280 Coulomb (1,000 Coulomb limit) were produced and connected to each other by using 30,765 bolts. Each ring consists of nine segments that had an average 28 day cylinder compressive strength of 70 MPa (10,000 psi) and can resist at least 127 years as

5396-544: Was by the Dutch consultancy Fugro . The tunnel boring machine (TBM) was supplied by the German manufacturer Herrenknecht . The Italian company Italferr was in charge of works management and project review on behalf of Administration. The French company Egis Group will be in charge of the operation and maintenance. The TBM section crossing the Bosphorus is 3.4 km (2.1 mi) long while another 2.0 km (1.2 mi)

5472-846: Was completed within ±5 cm (1.97 in) tolerance in 479 calendar days, resulting in an average advance rate of 7.0 m/d (23 ft/d) (9.0 m/d or 30 ft/d for working days) by three crews 24/7. The maximum advance rate was realized at marine sediment zone with 18.0 m/d (59 ft/d). Spent direct time for excavation and ringbuild were around 3,500 and 1,700 hours, respectively. In Trakya formation, 28 dyke zones were excavated with an average frequency of 90 m (300 ft) and thicknesses were varying between 1 and 120 m (3.3 and 393.7 ft). Furthermore, 440 disc cutters, 85 scrapers and 475 brushes were replaced by TBM crew and four times hyperbaric maintenance operations (total of 45 days) with specially trained divers (max. under 10.8 bar or 1.08 MPa or 157 psi first time in

5548-575: Was constructed to provide a second harbour crossing and to alleviate traffic congestion on the Sydney Harbour Bridge , without spoiling the iconic view. Other reasons for choosing a tunnel instead of a bridge include avoiding difficulties with tides, weather, and shipping during construction (as in the 51.5-kilometre or 32.0-mile Channel Tunnel ), aesthetic reasons (preserving the above-ground view, landscape, and scenery), and also for weight capacity reasons (it may be more feasible to build

5624-450: Was opened on 29 October 2013. The journey between the two continents takes about 5 minutes. Toll is collected in both directions; since February 2020, ₺ 36.40 (about $ 1 US ) for cars and ₺54.70 ($ 2 US) for minibuses. In February 2021 the toll increased by 26% to ₺46 (approx. $ 6.20) and ₺69 (~$ 9.30) respectively. In 1891, French railway engineer Simon Préault presented a preliminary project for an underwater tubular bridge "patented by

5700-451: Was specified as moment magnitude of 7.25 and design of functional and safety evaluation earthquakes have a return period of 500 and 2,500 years, respectively. Seismic joint locations defined during design phase were verified through continuous monitoring of cutterhead torques. The 3,340 m (3,650 yd) tunnel was excavated and constructed with a 13.7 m (45 ft) diameter Mixshield Slurry TBM exclusively designed and equipped with

5776-732: Was superseded by the Madrid M30 ringroad , Spain, and the Chong Ming tunnels in Shanghai , China. All of these machines were built at least partly by Herrenknecht . As of August 2013 , the world's largest TBM was " Big Bertha ", a 17.5-metre (57.5 ft) diameter machine built by Hitachi Zosen Corporation , which dug the Alaskan Way Viaduct replacement tunnel in Seattle, Washington (US). A temporary access shaft

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