75-623: Penmanshiel Tunnel is a now-disused railway tunnel near Grantshouse , Berwickshire , in the Scottish Borders region of Scotland. It was formerly part of the East Coast Main Line between Berwick-upon-Tweed and Dunbar . The tunnel was constructed between 1845 and 1846 by contractors Ross and Mitchell, to a design by John Miller , who was the engineer to the North British Railway . Upon completion,
150-695: 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
225-465: A concrete base at the lower level. Use of concrete base helped reduce the amount by which the floor had to be lowered. The process was judged to be safe so long as the walls of the tunnel were not undercut in the course of the works. In order to minimise disruption to both passenger and freight services on the busy main line, it was decided that each of the two tracks through the tunnel would be renewed consecutively rather than concurrently; while one track
300-449: 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
375-415: A memorial. One face of the obelisk displays a cross, while each of the other two faces commemorates one of the men killed. The memorial is adjacent to a road running over the hill and is marked on 1:50,000 and 1:25,000 scale OS maps , at grid reference NT 797670. Tunnel A tunnel is an underground or undersea passageway. It is dug through surrounding soil, earth or rock, or laid under water, and
450-523: A partition in the corridor, the surface of which was found to have been coated with a highly-flammable lacquer. Subsequent analysis of the lacquer indicated that it was composed of nearly 17% nitrocellulose and sustained "startling" combustion. Draughts of air from the open windows may have fanned the flames. Despite the noxious fumes and the severity of the blaze, which reduced the two carriages to their underframes, only seven passengers were injured, with no fatalities. The next significant event to occur at
525-467: 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,
600-496: A railway shuttle took over between Dunbar and Edinburgh . Other InterCity services reached Edinburgh by diverting from the East Coast Main Line at Newcastle and travelling via Carlisle and Carstairs . Since the tunnel was closed, the landscape has gradually returned to nature . The southern portal has been covered by the hillside, and the only clues to the route of the old line are a dry-stone wall marking
675-406: A south-bound express from Edinburgh. Seven passengers were injured, but there were no deaths. The second incident occurred on 17 March 1979 when, during improvement works, a length of the tunnel suddenly collapsed. Thirteen workers managed to escape, but two were killed. Later it was determined that it would be too dangerous and difficult to rebuild the tunnel, so it was sealed up and a new alignment
750-421: 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
825-434: 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
SECTION 10
#1732781153052900-747: 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,
975-432: 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
1050-485: 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. Portal (architecture) A portal is an opening in a wall of a building, gate or fortification, especially a grand entrance to an important structure. Doors, metal gates , or portcullis in
1125-505: 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
1200-494: 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
1275-401: 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
1350-515: 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
1425-698: 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
1500-429: 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
1575-569: 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
SECTION 20
#17327811530521650-471: 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
1725-848: 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
1800-472: 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
1875-679: 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
1950-610: 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
2025-489: 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
2100-426: The "extreme complexity" of the geology could ever have been appreciated by investigation of rock exposed in the tunnel or though other routine investigatory techniques. It was further noted that the degeneration of the overlying rock had made the tunnel "dangerously unstable" for many years prior to the collapse, and that the collapse would most probably have occurred at some time or another regardless of whether or not
2175-689: 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
2250-638: 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
2325-716: 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 ;
Penmanshiel Tunnel - Misplaced Pages Continue
2400-709: 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
2475-599: 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
2550-655: The accident. Despite this the British Railways Board was charged in the High Court of Justiciary at Edinburgh with breaching the Health and Safety at Work etc. Act 1974 by "having failed to do all that was reasonably practical to ensure that persons in the tunnel were not exposed to the risk of personal injury by the collapse of part of the [tunnel] structure", on the basis that a full geotechnical survey—whether futile or not—had not been conducted prior to
2625-427: The associated mortar, to be of reasonable strength; confirming observations made during the cutting of the samples, and also reports from repair works that had been conducted on the tunnel in the past. Geotechnical investigations into the surrounding hillside found evidence suggesting fracturing of the rock overlying the tunnel, but similarly this was not thought to be sufficiently definitive. Only during excavation of
2700-400: 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
2775-452: The brickwork by investigators showed that the crown of the arch was generally of sufficient thickness, but that this thickness tapered off through the haunches where the arch transitioned into the side walls. Other windows exposed cavities and voids in the rock behind the brickwork, some of which were filled with loose rock. On the whole though, these findings were deemed to be inconclusive. Tests conducted on samples of brickwork showed it, and
2850-502: 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
2925-425: The cutting for the bypass alignment did the "most revealing" piece of evidence become available: a detailed geological survey of the hill along the line of the cutting exposed an anticlinal structure of shattered and sheared rock that was found to intersect the line of the tunnel in close proximity to the area of the collapse. The report accordingly concluded that the collapse was likely the result of degeneration of
3000-471: The enlargement works had been undertaken. Nonetheless, the investigation thought it likely that the works contributed to the timing of the collapse, in that the already overloaded tunnel walls could not tolerate the slight increase in stress placed upon them by the excavation of the tunnel floor. Finally the report stated that—as the conditions leading to the collapse could not reasonably be foreseen—there were no grounds for finding any individual responsible for
3075-409: 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
Penmanshiel Tunnel - Misplaced Pages Continue
3150-441: 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
3225-405: 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
3300-640: 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
3375-435: 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
3450-440: The inspectorate found that the works on site "[appeared] to been carried out with proper care and foresight", and that there was no evidence to suggest that the side walls of tunnel had been subjected to excessive force or vibration during the upgrade works. Investigations into the remaining tunnel structure, particularly that adjacent to the collapsed area, revealed inconsistencies in the tunnel's construction. "Windows" cut through
3525-468: 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
3600-629: 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
3675-406: The new railway alignment on 7 May 1979, and it was completed on 20 August. The portals of the collapsed tunnel were sealed to prevent further access, and the approach cuttings were filled. During the closure, some trains from King's Cross terminated at Berwick , with onward services being provided by a fleet of buses, some towing trailers for luggage. The bus service went as far as Dunbar , where
3750-483: 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
3825-401: The opening can be used to control entry or exit. The surface surrounding the opening may be made of simple building materials or decorated with ornamentation . The elements of a portal can include the voussoir , tympanum , an ornamented mullion or trumeau between doors, and columns with carvings of saints in the westwork of a church . The term portal is also applied to the ends of
SECTION 50
#17327811530523900-540: 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
3975-522: 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
4050-490: 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,
4125-473: The railway boundary, and a disused bridge that used to carry the A1 main road over the line. As the collapsed portion of the tunnel was never excavated, the site became the final resting place of both workers who were killed in the collapse; Gordon Turnbull from Gordon , 22 miles (35 km) away, and Peter Fowler from Eyemouth . A three-sided obelisk was erected over the point where the tunnel collapsed to act as
4200-478: The railway that bypassed the tunnel. This decision resulted in a total of around 1 kilometre (1,100 yd) of existing railway being abandoned and replaced by a new section of line constructed in an open cutting, approximately 40 m (130 ft) to the west of the tunnel. This in turn necessitated a similar westward realignment of the A1 trunk road. The contractor Sir Robert McAlpine & Sons Ltd started work on
4275-482: 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
4350-405: The rock within the anticlinal structure overlying the tunnel, which progressively—but inconsistently—increased the loading on the tunnel's brick arch ring in a way that could not adequately be distributed into the surrounding hillside. The existence of the anticline would almost certainly have never been confirmed without the excavation of the bypass cutting, and it was considered "most unlikely" that
4425-542: 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
4500-504: The state of the tunnel walls throughout the works; "at no time" had any cracks or fractures been observed. The need to avoid undercutting the side walls during the excavation of the floor had also been observed with "great care", and a series of monitoring measurements taken periodically across the tunnel – using nails that had been machine-driven into the walls at 10-metre (33 ft) intervals especially for this purpose – had not revealed any movement. Accordingly,
4575-528: The tunnel and flowed to sea in the opposite direction, towards Cockburnspath . The tunnel was flooded to within 610 mm (2 ft) of the crown of the portal. The damage caused to other infrastructure by these floods led to the abandonment of much of the railway network in the south east of Scotland. On the evening of 23 June 1949 a fire broke out in the tenth coach of an express passenger train from Edinburgh to King's Cross , about 2.5 miles (4 km) beyond Cockburnspath. The train stopped somewhere near
SECTION 60
#17327811530524650-400: 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,
4725-437: The tunnel from floor to roof and totally enveloping a dumper truck and an excavator , along with the two men operating them. The 13 other people working inside the tunnel at the time of the collapse were able to escape successfully, but despite the efforts of rescuers (including a specialised mine rescue team) it was not possible to reach the two operators or to recover their bodies. An official HM Railway Inspectorate report
4800-475: The tunnel led to its abandonment. Work was being carried out in March 1979 to increase clearances within the tunnel, so that intermodal containers 8 ft 6 in (2.59 m) in height could be carried through it on flat wagons . This was performed by removing the existing track and ballast , digging out the floor of the tunnel by between 300 and 800 mm (12 and 31 in), and then laying new track on
4875-436: The tunnel wall, approximately 90 m (300 ft) from the southern portal . He decided that it would be wise to shore up the affected piece of the tunnel and was making his way towards the site office to arrange this when he heard the sound of the tunnel collapsing behind him. It is estimated that approximately 20 m (66 ft) of the tunnel arch collapsed, with the resultant rockfall filling 30 m (98 ft) of
4950-467: The tunnel was inspected by the inspector-general of railways, Major-General Charles Pasley , on behalf of the Board of Trade . The tunnel was 244 metres (267 yd) long, and carried two running lines in a single bore. During its 134-year existence, the tunnel was the location of two incidents investigated by HM Railway Inspectorate . The first was in 1949, when a serious fire destroyed two carriages of
5025-407: The tunnel, within one and a quarter minutes of the fire starting, but the fire spread rapidly and with such ferocity that, within seconds, the brake-composite carriage was engulfed and the fire had spread to the coach in front. Most passengers escaped by running to the guard's compartment or forwards along the corridor, but some were compelled to break the windows and jump down onto the track. One woman
5100-428: 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
5175-409: The works commencing. The Board entered a guilty plea and was fined £10,000. In the aftermath of the collapse British Rail originally intended to repair and re-open the tunnel, but this was ruled out as being excessively dangerous and difficult once investigations revealed the extent of the collapse. It was judged instead that it would be more expedient and cost-effective to construct a new alignment for
5250-408: Was closed for lowering, trains could continue to run on the adjacent open track. Work was completed on the "Up" (southbound) track by 10 March 1979, and trains were then transferred to this track by the following day, to allow the "Down" (northbound) track to be modified. Shortly before 3:45 a.m. on 17 March 1979, the duty railway works inspector noticed some small pieces of rock flaking away from
5325-575: 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
5400-611: Was made for the railway, in a cutting to the west of the hill. The tunnel was also affected by severe flooding in August 1948. On 12 August 1948, 159 millimetres (6.25 in) of rain fell in the area, the total for the week being 270 mm (10.5 in). Rain falling on the Lammermuir Hills surged into the Eye Water towards Reston , and the channel could not accommodate all of the water. The flood water then backed up
5475-449: Was prepared by Lieutenant Colonel I. K. A. McNaughton and released on 2 August 1983. The report concluded that, without access to the collapsed portion of the tunnel, it was impossible to be certain as to the "actual cause" of the collapse. Neither the tunnel's history, nor its condition immediately prior to commencement of the works, had given any significant cause for concern, and it was noted that workers had "paid particular attention" to
5550-419: Was seriously injured by doing this. The train crew reacted quickly to the incident. The two coaches behind the two ablaze were uncoupled and pushed back, leaving them isolated up the line. Having drawn forward and uncoupled the two burning vehicles, the driver proceeded with the front eight coaches to Grantshouse station . The cause of the fire was thought to be a cigarette end or lighted match dropped against
5625-732: 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
#51948