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160-466: The Transbay Tube is an underwater rail tunnel that carries Bay Area Rapid Transit 's four transbay lines under San Francisco Bay between the cities of San Francisco and Oakland in California . The tube is 3.6 miles (5.8 km) long, and attaches to twin bored tunnels. The section of rail between the nearest stations (one of which is underground) totals 6 miles (10 km) in length. The tube has

320-695: 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

480-408: A line shaft . Dogs were sometimes used on machines such as a treadmill, which could be adapted to churn butter. In the late 19th century specially designed power buildings leased space to small shops. These building supplied power to the tenants from a steam engine through line shafts. Electric motors were several times more efficient than small steam engines because central station generation

640-459: A CCJPA meeting, one with a combined tunnel for BART and regional rail, and another route with two separate tunnels. As of March 2023, a combined four-track tunnel or two separate tunnels for both BART and regular rail are no longer considered cost-effective due to reduced ridership in the Bay Area; planners will research one single tunnel dedicated to either BART service or regional rail service. CCJPA

800-404: A central maintenance/pedestrian gallery. Each tunnel has a bore approximately 17 feet (5.2 m) in diameter, with the track centerline offset 8 inches (200 mm) towards the outside from the bore centerline. The tunnels flank a gallery which contains maintenance and control equipment in the upper gallery, including a pressurized water line for firefighting. Each tunnel has 56 doors opening into

960-479: A delay. The idea of an underwater rail tunnel traversing San Francisco Bay from Oakland point was suggested by the San Francisco eccentric Emperor Norton in a proclamation that he issued on May 12, 1872. Emperor Norton issued another proclamation on September 17, 1872, threatening to arrest the city leaders of Oakland and San Francisco for neglecting his earlier proclamation. Official consideration to

1120-449: 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

1280-424: A light arc with carbon electrodes. However, it was not used to any great extent until a practical means of generating electricity was developed. Carbon arc lamps were started by making contact between two carbon electrodes, which were then separated to within a narrow gap. Because the carbon burned away, the gap had to be constantly readjusted. Several mechanisms were developed to regulate the arc. A common approach

1440-513: A long combined automobile and rail tunnel, indirectly endorsing the idea of a dedicated tunnel for electric rail traffic. The Davies and Modjeski proposal was joined by twelve other proposed projects to cross the Bay in October 1921, several of which featured rail service through long tunnels. In 1947, a joint Army-Navy Commission recommended an underwater tube as a means of relieving automobile congestion on

1600-527: A man entered the Tube through the portal at Embarcadero station and remained in it for more than an hour; while transit police were searching for him, trains continued to move through the Tube at slow speeds in manual mode. Service has been disrupted on multiple occasions after trains become stuck in the Transbay Tube, which is partially attributed to aging equipment. In addition to the 1979 fire, while moving through

1760-451: A maximum depth of 135 feet (41 m) below sea level. Built using the immersed tube technique, the Transbay tube was constructed on land in 57 sections, transported to the site, and then submerged and fastened to the bottom – primarily by packing its sides with sand and gravel. Opened in 1974, the tunnel was the final segment of the original BART system to open. All BART lines except

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1920-407: A moment's notice, require no expense of time for its management and be of modest cost both in original cost and in daily expense. To be efficient steam engines needed to be several hundred horsepower. Steam engines and boilers also required operators and maintenance. For these reasons the smallest commercial steam engines were about 2 horsepower. This was above the need for many small shops. Also,

2080-401: A new steel liner and higher-capacity pumps would be installed to reduce the possibility of flooding the tube, as the existing pumps would not be adequate in the worst-case seismic event. Work was projected to start in the summer of 2018 and is scheduled to take more than two years to complete. Service through the tube would be reduced or eliminated during the first hour and the last three hours of

2240-585: A parliamentary committee recommended passage of the landmark 1882 Electric Lighting Act, which allowed the licensing of persons, companies or local authorities to supply electricity for any public or private purposes. The first large scale central power station in America was Edison's Pearl Street Station in New York, which began operating in September 1882. The station had six 200 horsepower Edison dynamos, each powered by

2400-477: A patented sliding seismic joint which allows six degrees of freedom (translation along and rotation about three axes). As-designed, the joints allow movement of up to 4.25 inches (108 mm) along the tube's axis and up to 6.75 inches (171 mm) vertically or laterally. A restaurant was constructed atop the San Francisco transition structure (vent) on a pier behind the Ferry Building. The Oakland vent structure

2560-461: 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,

2720-416: A possible contributing factor because No. 117 was unable to move in road manual for forty seconds. In addition, the operator and line supervisor aboard No. 117 were unable to uncouple the damaged cars using the existing on-board controls because of an apparent short in the train control circuit; to uncouple the car and isolate the short, someone would have had to leave the train and manually disconnect

2880-430: A residential HP+PV system. It found that under typical inflation conditions, the lifecycle cost of natural gas and reversible, air-source heat pumps are nearly identical, which in part explains why heat pump sales have surpassed gas furnace sales in the U.S. for the first time during a period of high inflation. With higher rates of inflation or lower PV capital costs, PV becomes a hedge against rising prices and encourages

3040-611: A ride through the Transbay Tube. Tunnel A tunnel 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

3200-489: A rocking switch. Later segmented commutators were used to produce direct current. Around 1838-40, William Fothergill Cooke and Charles Wheatstone developed a telegraph. In 1840 Wheatstone was using a magneto that he developed to power the telegraph. Wheatstone and Cooke made an important improvement in electrical generation by using a battery-powered electromagnet in place of a permanent magnet, which they patented in 1845. The self-excited magnetic field dynamo did away with

3360-470: A separate steam engine. It was located in a business and commercial district and supplied 110 volt direct current to 85 customers with 400 lamps. By 1884 Pearl Street was supplying 508 customers with 10,164 lamps. By the mid-1880s, other electric companies were establishing central power stations and distributing electricity, including Crompton & Co. and the Swan Electric Light Company in

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3520-451: A small steam engine and boiler cost about $ 7,000 while an old blind horse that could develop 1/2 horsepower cost $ 20 or less. Machinery to use horses for power cost $ 300 or less. Many power requirements were less than that of a horse. Shop machines, such as woodworking lathes, were often powered with a one- or two-man crank. Household sewing machines were powered with a foot treadle; however, factory sewing machines were steam-powered from

3680-421: 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

3840-585: A sustainable way. Similarly, many households in the developing and developed world suffer from fuel poverty and cannot heat their houses enough. Existing heating practices are often polluting. A key sustainable solution to heating is electrification ( heat pumps , or the less efficient electric heater ). The IEA estimates that heat pumps currently provide only 5% of space and water heating requirements globally, but could provide over 90%. Use of ground source heat pumps not only reduces total annual energy loads associated with heating and cooling, it also flattens

4000-421: A thermal battery into the heat pump+solar energy heating system. It is easier to sustainably produce electricity than it is to sustainably produce liquid fuels. Therefore, adoption of electric vehicles is a way to make transport more sustainable. Hydrogen vehicles may be an option for larger vehicles which have not yet been widely electrified, such as long distance lorries. While electric vehicle technology

4160-434: 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

4320-710: 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,

4480-432: 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

4640-563: Is pumped-storage hydroelectricity , which requires locations with large differences in height and access to water. Batteries , and specifically lithium-ion batteries , are also deployed widely. They contain cobalt , which is largely mined in Congo , a politically unstable region. More diverse geographical sourcing may ensure the stability of the supply-chain and their environmental impacts can be reduced by downcycling and recycling. Batteries typically store electricity for short periods; research

4800-476: Is 328 feet (100 m), measured along the tunnels' bore; sections are 48 feet (15 m) wide, 24 feet (7.3 m) high, and weigh approximately 10,000 short tons (9,100 t) each. To conform with the route, 15 tube sections were curved horizontally, 4 were curved vertically, 2 had horizontal and vertical curves, and the remaining 36 sections were straight. Each section of the Tube cost approximately US$ 1,500,000 (equivalent to $ 12,460,000 in 2023), based on

4960-410: Is a "sticky" form of energy, in that it tends to stay in the continent or island where it is produced. It is also multi-sourced; if one source suffers a shortage, electricity can be produced from other sources, including renewable sources . As a result, in the long term it is a relatively resilient means of energy transmission. In the short term, because electricity must be supplied at the same moment it

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5120-550: 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. Electrification The electrification of particular sectors of the economy, particularly out of context, is called by modified terms such as factory electrification , household electrification , rural electrification and railway electrification . In

5280-418: Is also used as a duct, moving 300,000 cubic feet per minute (8,500 m/min) of air under forced circulation. The tunnels are vented to the atmosphere at the San Francisco and Oakland ends and are vented to each other (through the upper gallery) with remotely-operated dampers 6 feet (1.8 m) long by 3 feet (0.91 m) high over every third door. Each end of the tube is secured to the vent structures with

5440-423: Is considering three possible routes, one for regional rail and two for BART extensions. During construction, the Transbay Tube was also used briefly as a shooting location for the ending of George Lucas 's film THX 1138 . The final vertical climb out to daylight was actually filmed, with the camera rotated 90°, in the incomplete (and decidedly horizontal) Transbay Tube. The scene was filmed before installation of

5600-501: Is consumed, it is somewhat unstable, compared to fuels that can be delivered and stored on-site. However, that can be mitigated by grid energy storage and distributed generation . Solar and wind are variable renewable energy sources that supply electricity intermittently depending on the weather and the time of day. Most electrical grids were constructed for non-intermittent energy sources such as coal-fired power plants. As larger amounts of solar and wind energy are integrated into

5760-488: Is exacerbated by the concrete enclosure and the fact that tracks are curved when the tunnel crosses beneath the San Francisco–Oakland Bay Bridge , causing a high-pitched screeching sound. In 2015, after replacing 6,500 feet (2,000 m) and grinding down (smoothing) 3 miles (4.8 km) of rail in the tube, BART reported a reduction of noise and positive feedback from riders. Ship traffic passing through

5920-701: Is expected to be the first step in the electrification of the chemical industry with an expected large-scale implementation by 2025. Some cities in the United States have started prohibiting gas hookups for new houses, with state laws passed and under consideration to either require electrification or prohibit local requirements. The UK government is experimenting with electrification for home heating to meet its climate goals. Ceramic and Induction heating for cooktops as well as industrial applications (for instance steam crackers) are examples of technologies that can be used to transition away from natural gas. Electricity

6080-500: 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

6240-471: Is located in the middle of a Port of Oakland container yard. The Transbay Tube has required earthquake retrofitting , both on its exterior and interior. The total cost of seismic retrofits was estimated at US$ 330,000,000 (equivalent to $ 532,300,000 in 2023) in 2004. A 1991 study, commissioned at the recommendation of the Governor's Board of Inquiry in the wake of the 1989 Loma Prieta earthquake , found

6400-552: Is ongoing into technology with sufficient capacity to last through seasons. Pumped hydro storage and power-to-gas with capacity for multi-month usage has been implemented in some locations. As of 2018, thermal energy storage is typically not as convenient as burning fossil fuels . High upfront costs form a barrier for implementation. Seasonal thermal energy storage requires large capacity; it has been implemented in some high-latitude regions for household heat. The earliest commercial uses of electricity were electroplating and

6560-409: Is produced even during poor weather; during optimal weather energy generation may have to be curtailed . The final mismatch may be covered by using dispatchable energy sources such as hydropower, bioenergy, or natural gas. Energy storage helps overcome barriers for intermittent renewable energy, and is therefore an important aspect of a sustainable energy system. The most commonly used storage method

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6720-487: 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

6880-472: Is relatively mature in road transport, electric shipping and aviation are still early in their development, hence sustainable liquid fuels may have a larger role to play in these sectors. A large fraction of the world population cannot afford sufficient cooling for their homes. In addition to air conditioning , which requires electrification and additional power demand, passive building design and urban planning will be needed to ensure cooling needs are met in

7040-401: 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

7200-441: 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

7360-673: 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

7520-556: 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

7680-501: The Faraday disk , a type of homopolar generator , using a copper disc rotating between the poles of a horseshoe magnet . Faraday's first electromagnetic generator produced a small DC voltage. Around 1832, Hippolyte Pixii improved the magneto by using a wire wound horseshoe, with the extra coils of conductor generating more current, but it was AC. André-Marie Ampère suggested a means of converting current from Pixii's magneto to DC using

7840-527: The Orange Line operate through the Transbay Tube, making it one of the busiest sections of the system in terms of passenger and train traffic. During peak commute times, over 28,000 passengers per hour travel through the tunnel with headways as short as 2.5 minutes. BART trains can reach their highest speeds in the tube, up to 80 miles per hour (129 km/h), although trains typically operate at 70 miles per hour (113 km/h) unless trying to recover from

8000-464: 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

8160-797: 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

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8320-466: 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

8480-490: The US$ 90,000,000 (equivalent to $ 747,770,000 in 2023) construction contract. The steel shell is 5 ⁄ 8 inch (16 mm) thick, and has just enough strength to support its own weight and resist hoop stresses; an external consultant, Professor Ralph Brazelton Peck , convinced project engineer Tom Kuesel that thin shells were adequate because the soil loads would naturally form an arch. The tube consists of two tunnels and

8640-665: 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

8800-591: 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

8960-408: The telegraph . In the years 1831–1832, Michael Faraday discovered the operating principle of electromagnetic generators. The principle, later called Faraday's law , is based on an electromotive force generated in an electrical conductor that is subjected to a varying magnetic flux as, for example, a wire moving through a magnetic field. Faraday built the first electromagnetic generator, called

9120-486: 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

9280-689: 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

9440-564: The 1850s, many of these problems were solved by the arc lamp invented by William Petrie and William Staite. The lamp used a magneto-electric generator and had a self-regulating mechanism to control the gap between the two carbon rods. Their light was used to light up the National Gallery in London and was a great novelty at the time. These arc lamps and designs similar to it, powered by large magnetos, were first installed on English lighthouses in

9600-638: 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

9760-431: The 1970s and 1980s—from 49% of the world's population in 1970 to 76% in 1990. By the early 2010s, 81–83% of the world's population had access to electricity. Clean energy is mostly generated in the form of electricity, such as renewable energy or nuclear power . Switching to these energy sources requires that end uses, such as transport and heating, be electrified for the world's energy systems to be sustainable. In

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9920-687: 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 ;

10080-523: The Bay can damage the anodes used in the Tube's cathodic protection system when dropping anchor. Since the anodes protrude from the filled trench surrounding the Tube, they are more vulnerable to damage. Marine traffic is restricted from dropping anchors when over the Tube, but BART conducts routine inspections for anode damage. The Tube was closed briefly on January 31, 2014, after a drifting freighter dropped anchor near it at 8:45 a.m. to maintain position. The Coast Guard notified BART officials

10240-404: The Bay floor. The route was deliberately chosen to avoid bedrock as much as possible so the tube was free to flex, avoiding concentrated bending stresses. Design concepts and route alignment were completed by July 1960. A 1961 report estimated the cost of the Transbay Tube at US$ 132,720,000 (equivalent to $ 1,353,210,000 in 2023). Construction was started on the tube in 1965, and the structure

10400-517: The Bay's bottom. Once the section was in place, divers connected the section with the sections that had already been placed underwater, the bulkheads between placed sections were removed and a protective layer of sand and gravel was packed against the sides. Cathodic protection was provided to resist corrosive action from the Bay's salt water. The project cost approximately $ 180 million in 1970 (equivalent to $ 1.09 billion in 2023), with $ 90 million of that cost being spent on construction,

10560-691: 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

10720-594: The Port of Oakland. A 2010 paper concluded the distance the tube would rise due to liquefaction was limited based on model testing of potential liquefaction mechanisms, and questioned the justification for the compaction effort. On the interior of the tube, BART began a major retrofitting initiative in March 2013, which involved installing heavy steel plates at various locations inside the tube that most needed strengthening, to protect them from sideways movement in an earthquake. A vehicle

10880-415: The Transbay Tube, with the operator reporting thick smoke coming from his train. The collector shoe assemblies on the number five and six cars of No. 117 had broken after striking the line switchbox cover which had fallen off No. 363 and jammed into the cover of the third rail. The NTSB later concluded the resulting electrical arcing between the train and the energized third rail ignited components on

11040-503: The Tube, a train split and was automatically stopped after a coupler failed in March 2010. Two maintenance vehicles collided within the Tube in September 2014, damaging a section of track and forcing BART traffic to rely on a single track. In January 2015, a train was forced to stop in the Tube after the brake inadvertently engaged on a car. A train in December 2016 was forced to switch to manual mode and proceed at reduced speed after stopping in

11200-587: The Tube, and another faulty brake forced a train to stop in the Tube in April 2017. According to a 2010 survey by the San Francisco Chronicle , the Transbay Tube is the noisiest part of the BART system, with sound pressure levels inside the train reaching 100 decibels (comparable to a jackhammer). The noise, which according to BART "has been compared to banshees , screech owls , or Doctor Who 's TARDIS run amok"

11360-437: The U.S. and Canada the use of heat pumps (HP) is economic if powered with solar photovoltaic (PV) devices to offset propane heating in rural areas and natural gas heating in cities. A 2023 study investigated: (1) a residential natural gas-based heating system and grid electricity, (2) a residential natural gas-based heating system with PV to serve the electric load, (3) a residential HP system with grid electricity, and (4)

11520-471: The U.S. from 1870 to 1880 each man-hour was provided with .55 hp. In 1950 each man-hour was provided with 5 hp, or a 2.8% annual increase, declining to 1.5% from 1930 to 1950. The period of electrification of factories and households from 1900 to 1940, was one of high productivity and economic growth. Most studies of electrification and electric grids focused on industrial core countries in Europe and

11680-559: The UK, Thomson-Houston Electric Company and Westinghouse in the US and Siemens in Germany . By 1890 there were 1000 central stations in operation. The 1902 census listed 3,620 central stations. By 1925 half of power was provided by central stations. One of the biggest problems facing the early power companies was the hourly variable demand. When lighting was practically the only use of electricity, demand

11840-525: 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

12000-496: The United States. Elsewhere, wired electricity was often carried on and through the circuits of colonial rule. Some historians and sociologists considered the interplay of colonial politics and the development of electric grids: in India, Rao showed that linguistics-based regional politics—not techno-geographical considerations—led to the creation of two separate grids; in colonial Zimbabwe (Rhodesia), Chikowero showed that electrification

12160-457: The adoption of heat pumps by also locking in both electricity and heating cost growth. The study concludes: "The real internal rate of return for such prosumer technologies is 20x greater than a long-term certificate of deposit , which demonstrates the additional value PV and HP technologies offer prosumers over comparably secure investment vehicles while making substantive reductions in carbon emissions." This approach can be improved by integrating

12320-428: The agency responsible for Capitol Corridor commuter rail service, began planning to conduct a feasibility study to narrow the possible alignment options for the proposed second crossing. The study would continue to consider standard-gauge railway options in order to allow connections to Caltrain, CHSR, Capitol Corridor, and potentially other rail services. In September 2022, two alternative routes were unveiled at

12480-435: The anchor appeared to be close to the Tube at 11:55 a.m., based on the ship's position, leading to a suspension of Tube service for approximately 20 minutes while inspections were conducted. No damage was found, and the Tube was reopened at 12:15 p.m. Harbor pilots later noted the ship had anchored 1,200 feet (370 m) southwest of the Tube. Two trains that had been passing through the Tube were stopped in place while

12640-461: The battery to power electromagnets. This type of dynamo was made by several people in 1866. The first practical generator, the Gramme machine , was made by Z.T. Gramme, who sold many of these machines in the 1870s. British engineer R.E.B. Crompton improved the generator to allow better air cooling and made other mechanical improvements. Compound winding, which gave more stable voltage with load, improved

12800-445: The blaze. The forty passengers and two BART employees aboard the stricken train were rescued by another train passing in the opposite direction. Poor communication and coordination had hampered the response, and the lessons learned during the fire played a key role in developing National Fire Protection Association transit industry guidelines (NFPA 130, Standard for Fixed Guideway Transit and Passenger Rail Systems ). The cause of

12960-400: 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

13120-461: The car, causing air tanks and suspension airbags to explode on the fifth and sixth cars. Central operations shut down power to the third rail, but restored it 40 seconds later in an effort to uncouple the lead portion of the train from the burning cars. This was unsuccessful, and vent fans were turned on at 6:08 p.m. to attempt to clear the smoke, and the third rail was again powered down at 6:15 p.m. A BART line supervisor who had been riding on

13280-498: 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

13440-509: The context of sustainable energy , terms such as transport electrification (referring to electric vehicles ) or heating electrification (referring to heat pumps ) are used. It may also apply to changing industrial processes such as smelting, melting, separating or refining from coal or coke heating, or to chemical processes to some type of electric process such as electric arc furnace , electric induction or resistance heating, or electrolysis or electrolytic separating. Electrification

13600-402: The control cables had failed in the eastbound tunnel due to the spread of the fire. BART proposed new evacuation plans to the San Francisco and Oakland fire chiefs by February, but BART service through the Transbay Tube did not resume until April 1979, with California Public Utilities Commissioner Richard D. Gravelle warning "the patrons of BART who utilize its services should be fully aware that

13760-599: The difficulty in obtaining information from either Oakland or BART. The fire initially was declared under control at 10:45 p.m., although the fires were not yet fully extinguished; a final declaration of control was made at 1:31 a.m. on January 18. Later that day, at approximately 6 p.m., Oakland firefighters responded to flare-up in the gutted train at BART's storage yard. BART would spend US$ 1,100,000 (equivalent to $ 4,620,000 in 2023) in tube repairs and safety improvements on top of losing US$ 1,000,000 (equivalent to $ 4,200,000 in 2023) in revenue due to

13920-560: The eastbound tunnel which drew smoke from the westbound tunnel through the open doors (west #44 and #45) into the gallery and the eastbound tunnel (through open eastbound door #43), completely filling the 670 ft-long (200 m) gallery between doors #43 and #45. By this time, 10 more firefighters and a lieutenant had responded, entering the gallery through the Oakland vent structure; having encountered smoke on their walk in, they had donned portable air masks with 30-minute supplies, they reached

14080-523: The electric demand curve by eliminating the extreme summer peak electric supply requirements. However, heat pumps and resistive heating alone will not be sufficient for the electrification of industrial heat. This because in several processes higher temperatures are required which cannot be achieved with these types of equipment. For example, for the production of ethylene via steam cracking temperatures as high as 900 °C are required. Hence, drastically new processes are required. Nevertheless, power-to-heat

14240-513: The electrical cable underneath the coupler to the damaged cars. Critically, nine minutes elapsed between the time that power was restored and when the line supervisor informed BART central they were unable to uncouple the cars, which allowed the fire to grow. On the other hand, the low passenger count and the presence of a line supervisor allowed the passengers to evacuate into the lead car quickly. Dispatching No. 111 with over 1,000 passengers onboard could have resulted in an even larger disaster if

14400-409: 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

14560-555: The existing Transbay Tube. The proposed four-bore tunnel would emerge at the Salesforce Transit Center to provide connecting service to Caltrain and the planned California High-Speed Rail (CHSR) system. The second Tube would provide two tracks for BART trains, and two tracks for conventional/high-speed rail (the BART system and conventional U.S. rail use different and incompatible rail gauges and operate under different sets of safety regulations). In 2018, BART and CCJPA,

14720-441: 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

14880-449: The fire was traced to a damaged third rail collector shoe that caused electrical arcing on Train No. 117. Earlier that day, ten-car Train No. 363 had made an emergency stop in the Transbay Tube while traveling towards San Francisco at approximately 4:30 p.m., reporting smoke and a possible fire. Troubleshooting without an external inspection revealed No. 363 had broken derail bars on

15040-410: The fire. No. 900 sustained heat damage to the first car, and all ten cars sustained smoke damage. The tunnel sustained heat damage in the vicinity of the fire; portions of the ceiling concrete had spalled and exposed the reinforcing steel, overhead cables were destroyed, and the steel handrail between doors #43 and #44 had been warped by the heat. The shutdown of power to the third rail was cited as

15200-740: The first electrical engineering firms in the world. Various forms of incandescent light bulbs had numerous inventors; however, the most successful early bulbs were those that used a carbon filament sealed in a high vacuum. These were invented by Joseph Swan in 1878 in Britain and by Thomas Edison in 1879 in the US. Edison’s lamp was more successful than Swan’s because Edison used a thinner filament, giving it higher resistance and thus conducting much less current. Edison began commercial production of carbon filament bulbs in 1880. Swan's light began commercial production in 1881. Swan's house, in Low Fell , Gateshead,

15360-409: The full speed of 80 miles per hour (130 km/h), carrying approximately 100 passengers including BART officials, dignitaries and reporters. The tunnel is set in a trench 60 feet (18 m) wide with a gravel foundation 2 feet (0.61 m) deep. Lasers were used to guide the dredging of the trench and the laying of the gravel foundation, maintaining route accuracy of within 3 inches (76 mm) for

15520-446: The gallery between doors #44 and #45 just as No. 111 departed, rapidly filling the gallery with thick smoke. The tunnel exit doors are locked from the gallery side and require a key to open; with smoke filling the gallery, the keyholes were obscured and the firefighters were unable to evacuate to the eastbound tunnel. The firefighters began to make their way eastward in the gallery as a single-file human chain, through thick smoke. By

15680-526: The gallery via west door #42; they boarded the rescue train (No. 111) through door #43. After the rescued passengers boarded No. 111, firefighters searched No. 117 for any remaining passengers, informing central dispatch at 6:59 p.m. that all passengers had been evacuated. Dispatchers commanded No. 111 to proceed in automatic operation mode to West Oakland to transfer passengers to hospitals. The train quickly accelerated to its top speed of 80 miles per hour (130 km/h) creating pressure in

15840-403: The grid, changes have to be made to the energy system to ensure that the supply of electricity is matched to demand. In 2019, these sources generated 8.5% of worldwide electricity, a share that has grown rapidly. There are various ways to make the electricity system more flexible. In many places, wind and solar production are complementary on a daily and a season scale: There is more wind during

16000-405: 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

16160-508: The idea was first given in October 1920 by Major General George Washington Goethals , the builder of the Panama Canal . The alignment of Goethals's proposed tube, from the foot of Market St. to the Oakland mole , was almost exactly the same as today's Transbay Tube. His proposal called for building on bay mud, which anticipated some of the seismic design aspects of the finished Transbay Tube, and

16320-587: 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

16480-435: 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

16640-412: The inspection was conducted. Trains were delayed by 15 to 20 minutes, with normal service resuming around 1 p.m. In April 2017, the derrick barge Vengeance , which was working for BART performing Tube anode maintenance, capsized and sank at night during a late winter storm. The barge came to rest atop the fill overlaying the Transbay Tube, but did not disrupt transit operations. The primary concern

16800-501: The instant order [to reopen service] does not in any way provide a guarantee of safe service." Both the Oakland and San Francisco fire departments criticized BART officials for failing to relinquish control of the emergency situation to the fire departments. As a precaution, BART's emergency plans dictate that trains stop during an earthquake , except for trains in the Transbay Tube or the Berkeley Hills Tunnel , which proceed to

16960-468: 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

17120-404: The last San Francisco stop, Embarcadero . At 6:21 p.m., No. 111 moved in automatic mode into the eastbound tunnel, stopping with its rearmost car at eastbound tunnel exit door #43, adjacent to the stricken No. 117. The passengers from No. 117 had been led through the train and out the operator's compartment window in the lead car, then along the smoke-filled westbound tunnel into

17280-509: The load factor around the world was greater than 50%, mainly due to motor load. Before widespread power distribution from central stations, many factories, large hotels, apartment and office buildings had their own power generation. Often this was economically attractive because the exhaust steam could be used for building and industrial process heat, which today is known as cogeneration or combined heat and power (CHP). Most self-generated power became uneconomical as power prices fell. As late as

17440-462: The load factor. The way this was eventually accomplished was through motor load. Motors are used more during daytime and many run continuously. Electric street railways were ideal for load balancing. Many electric railways generated their own power and also sold power and operated distribution systems. The load factor adjusted upward by the turn of the 20th century—at Pearl Street the load factor increased from 19.3% in 1884 to 29.4% in 1908. By 1929,

17600-401: The loss of tube service. Train No. 363 sustained damage to its second, fifth, sixth, eight, and ninth cars. The line switch box cover was missing from the fifth car, and the sixth and eighth cars had broken derail bars. No. 117 had smoke damage to the interior of its first three cars; the fourth car was damaged by smoke and fire, and the fifth, sixth, and seventh cars were destroyed in

17760-607: 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

17920-412: The lower gallery, spaced approximately 330 feet (100 m) apart, numbered consecutively from the San Francisco side of the tube. The doors are locked from the gallery side and can be opened inwards (toward the gallery) from the tunnel through emergency hardware. Between doors, the tunnel has narrow 2.5-foot (0.76 m) wide walkways adjacent to the gallery space. The upper section of the gallery space

18080-533: The mid 1850s, but the technology suffered power limitations. The first successful arc lamp (the Yablochkov candle ) was developed by Russian engineer Pavel Yablochkov using the Gramme generator . Its advantage lay in the fact that it did not require the use of a mechanical regulator like its predecessors. It was first exhibited at the Paris Exposition of 1878 and was heavily promoted by Gramme. The arc light

18240-455: The nearest station. The lines are then inspected for damage, and resume normal operation if no damage is found. The largest to date was the 1989 Loma Prieta earthquake . During the 1989 earthquake, a train passing through the Tube was ordered to stop, although the operator reported no apparent motion. After inspection, the tube was found to be safe, and was reopened just six hours later, with regular service resuming system-wide twelve hours after

18400-530: The night and in winter, when solar energy production is low. Linking distant geographical regions through long-distance transmission lines allows for further cancelling out of variability. Energy demand can be shifted in time through energy demand management and the use of smart grids , matching the times when variable energy production is highest. With storage, energy produced in excess can be released when needed. Building additional capacity for wind and solar generation can help to ensure that enough electricity

18560-495: The number six and eight cars, and an engaged parking brake on the number nine car. After clearing the derail bar circuits and manually releasing the parking brake, No. 363 was cleared to proceed, and upon reaching the end of the line in Daly City, was taken out of service for inspection. A line switchbox cover had fallen off No. 363 and was resting on the third rail, which was not seen by following trains until it jammed against

18720-483: 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

18880-434: The operating characteristics of generators. The improvements in electrical generation technology in the 19th century increased its efficiency and reliability greatly. The first magnetos only converted a few percent of mechanical energy to electricity. By the end of the 19th century the highest efficiencies were over 90%. Sir Humphry Davy invented the carbon arc lamp in 1802 upon discovering that electricity could produce

19040-540: 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

19200-402: The originally-projected completion date, after clearing California Public Utilities Commission concerns regarding the automated dispatch system. The first test run was performed by a train under automatic control on August 10, 1973. Train No. 222 ran from West Oakland to Montgomery Street in seven minutes at 68 to 70 miles per hour (109 to 113 km/h) and returned in six minutes at

19360-510: 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

19520-485: 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,

19680-565: The quake. Many area highways were damaged by the event, and with the Bay Bridge closed for a month due to a section of the upper deck falling onto the lower deck on a truss section of the east span, the Transbay Tube was the only passable direct way between San Francisco and Oakland. In October 2012 and August 2013, pedestrians entered the Tube through the Embarcadero station, prompting shutdowns and delays in Transbay service. In late December 2016,

19840-412: The rate charged by the gas company, so the town council decided to use electricity. The system lit up arc lamps on the main streets and incandescent lamps on a few side streets with hydroelectric power. By 1882 between 8 and 10 households were connected, with a total of 57 lights. The system was not a commercial success, and the town reverted to gas. The first large scale central distribution supply plant

20000-682: The remainder going towards laying rails, electrification, ventilation and train control systems. The western terminus of the Tube directly connects to the downtown Market Street subway near the Ferry Building , north of the Bay Bridge. The tube crosses under the western span of the Bay Bridge between the San Francisco Peninsula and Yerba Buena Island , and emerges in Oakland along 7th Street, west of Interstate 880 . The tube has 57 sections; each section ranges from 273 to 336 feet (83 to 102 m) long. The average length of each section

20160-482: 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

20320-458: The seismic joints would "likely remain intact and functional after the next earthquake." However, settling of the tube within its trench and the Loma Prieta quake had reduced the allowable movement of the seismic joints to as little as 1.5 inches (38 mm). The 1991 study was followed by a more detailed BART Seismic Vulnerability Study , published in 2002, which concluded the fill packed around

20480-465: The service day. On January 17, 1979, at approximately 6 p.m., an electrical fire broke out on a San Francisco-bound seven-car train (Train No. 117) as it was passing through the tube. One firefighter (Lt. William Elliott, 50, of the Oakland Fire Department ) was killed by smoke and toxic fume inhalation (generated from burning plastic materials) during the effort to extinguish

20640-528: 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

20800-511: The then-ten-year-old Bay Bridge . The recommendation was issued in a report undertaken to determine the feasibility of the Reber Plan . Seismic studies commenced in 1959, including boring and testing programs in 1960 and 1964, and the installation of an earthquake recording system on the Bay floor. The tube's route was modified after preliminary surveys were unable to identify a continuous bedrock profile, requiring more precise boring and probing of

20960-424: The third rail coverboard, breaking the collector shoe on No. 117, which caused a short circuit and electrical arcing. The train following No. 363 was dispatched to run in "road manual" mode, where the train is controlled by the onboard operator, rather than by the computerized central control system. That train reported seeing derail bar debris between the tracks near where No. 363 had stopped, but that

21120-404: The time they reached the area of door #51, their portable air masks were starting to run low, and Lt. William Elliott began to have trouble, requiring assistance from his fellow firefighters. At 7:09 p.m., a firefighter called for help from a phone box and upon reaching a clear section of the tunnel, train No. 377 was dispatched from West Oakland in "road manual" to rescue the firefighters;

21280-411: The track supports, with Robert Duvall 's character using exposed reinforcing bars as a ladder. The television adaptation of Terry Brooks 's Shannara series of books, The Shannara Chronicles , is partly set in the Bay Area, and part of the journey/quest routes the protagonists through the Transbay Tube. One of the early sections of the video game Dead Space features a sound sample taken from

21440-414: The tracks were clear and available for service. The train immediately following also ran in "road manual," but subsequent trains were dispatched through the tube in automatic mode, including seven-car No. 117, the tenth train to enter the westbound tube after No. 363; No. 117 had 40 passengers onboard. No. 117 came to an emergency stop at 6:06 p.m., about 1.5 miles (2.4 km) into

21600-579: The train helped gather passengers in the lead car, including one blind passenger. BART central dispatch attempted to call the Oakland Fire Department, but unintentionally called San Francisco instead at 6:09 p.m. The Oakland Fire Department responded to the West Oakland station, where nine firefighters and two BART policemen boarded Train No. 900 running in "road manual." No. 900 was forced to stop at approximately 1 mile (1.6 km) into

21760-443: The train operator moved with passengers on board because she assumed the cause of the delay had been resolved. After the rescue train returned to West Oakland at approximately 8:10 p.m., the firefighters were taken to area hospitals for treatment. Elliott had exhausted his oxygen supply, and died of smoke inhalation and cyanide poisoning. The response was delayed in part because of the coordination between BART central dispatch and

21920-489: The trench and 1.8 inches (46 mm) for the foundation. Construction of the trench required dredging 5,600,000 cubic yards (4,300,000 m) of material from the Bay. The structure is made of 57 individual sections that were built on land at the Bethlehem Steel shipyard on Pier 70 and towed out into the bay by a large catamaran barge . After the steel shell was completed, water-tight bulkheads were fitted and concrete

22080-473: The tube might be prone to soil liquefaction during an intense earthquake, which could allow the buoyant hollow tube to break loose from its anchorages or cause movement that would exceed the capacity of the sliding seismic joints. Retrofitting work required the fill to be compacted, to make it denser and less prone to liquefaction. Compaction started in Summer 2006 at the east end of the tube, on property belonging to

22240-406: The tube to remove an auxiliary box cover and a derail bar from the track, and eventually stopped approximately 200 feet (61 m) behind No. 117, where the train operator reported the third rail was damaged and the rear car was on fire with heavy black smoke. Upon reaching No. 117, the responders became separated, with one policeman and seven firefighters proceeding into the gallery between

22400-400: 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,

22560-502: The tunnels, and the rest forced by the smoke to return to No. 900. However, the group in the gallery had left the door (westbound tunnel exit door #44) open to the tunnel for the others to follow; the returning policeman opened a second door (west #45) while setting up a maintenance telephone to communicate with central dispatch, but was forced by the smoke to abandon that position, leaving that door open as well. Train No. 111, with over 1,000 passengers on board, had been holding at

22720-406: The two bores of the tube early midweek (Tuesdays, Wednesdays and Thursdays), resulting in delays of 15–20 minutes. The work, originally estimated to last approximately 14 months, was completed by December 2013, after only 8 months of construction. In December 2016, BART awarded a US$ 267,000,000 (equivalent to $ 338,970,000 in 2023) contract to perform further seismic retrofitting. In this phase,

22880-456: The two cities' respective fire departments. San Francisco called BART central back at 6:19 p.m., but were advised that Oakland had already responded. Meanwhile, Oakland called San Francisco at 6:32 p.m. to advise them a train was on fire in the tunnel, so San Francisco dispatched a team to wait at Embarcadero at 6:36 p.m., but the San Francisco units did not proceed until 7:52 p.m. and did not arrive until 8:15 p.m. because of

23040-428: 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

23200-483: Was called "the greatest engineering achievement of the 20th Century" by the National Academy of Engineering , and it continues in both rich and poor countries. Electric lighting is highly desirable. The light is much brighter than oil or gas lamps, and there is no soot. Although early electricity was very expensive compared to today, it was far cheaper and more convenient than oil or gas lighting. Electric lighting

23360-439: Was completed after the final section was lowered on April 3, 1969. BART sold commemorative bronzed aluminum coins to mark the placement of the final section. Prior to being fitted out, the tube was opened for visitors to walk through a small portion on November 9, 1969. The tracks and electrification needed for the trains were finished in 1973, and the tube was opened to service on September 16, 1974, five years after

23520-566: 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

23680-405: Was custom-built to handle the 4-short-ton (3.6 t), 2.5-inch (64 mm) thick plates; once hoisted in place, the plates were bolted to the existing concrete walls and welded together, end-to-end. The contract for US$ 7,735,000 (equivalent to $ 10,265,000 in 2023) was awarded to California Engineering Contractors for installation. In order to complete this work during 2013, BART closed one of

23840-461: Was estimated to cost up to US$ 50,000,000 (equivalent to $ 854,100,000 in 2023). A competing bridge-and-tunnel proposal was advanced in July 1921 by J. Vipond Davies and Ralph Modjeski , closer to the alignment of a proposed Southern Crossing , between Mission Rock and Potrero Point in San Francisco due east to Alameda . Davies and Modjeski were critical of the ventilation issues that would arise from

24000-422: Was high during the first hours before the workday and the evening hours when demand peaked. As a consequence, most early electric companies did not provide daytime service, with two-thirds providing no daytime service in 1897. The ratio of the average load to the peak load of a central station is called the load factor. For electric companies to increase profitability and lower rates, it was necessary to increase

24160-550: Was installed along the half mile length of Avenue de l'Opéra , Place du Theatre Francais and around the Place de l'Opéra in 1878. R. E. B. Crompton developed a more sophisticated design in 1878 which gave a much brighter and steadier light than the Yablochkov candle. In 1878, he formed Crompton & Co. and began to manufacture, sell and install the Crompton lamp. His concern was one of

24320-485: Was more efficient than small steam engines and because line shafts and belts had high friction losses. Electric motors were more efficient than human or animal power. The conversion efficiency for animal feed to work is between 4 and 5% compared to over 30% for electricity generated using coal. Electrification and economic growth are highly correlated. In economics, the efficiency of electrical generation has been shown to correlate with technological progress . In

24480-463: Was opened at Holborn Viaduct in London in 1882. Equipped with 1000 incandescent lightbulbs that replaced the older gas lighting, the station lit up Holborn Circus including the offices of the General Post Office and the famous City Temple church . The supply was a direct current at 110 V; due to power loss in the copper wires, this amounted to 100 V for the customer. Within weeks,

24640-411: Was poured to form the 2.3-foot (0.70 m)-thick interior walls and track bed. They were then floated into place (positioned above where they were to sit), and the barge was tethered to the Bay floor, acting as a temporary tension leg platform. The section was ballasted with 500 short tons (450 t) of gravel before being lowered into a trench packed with soft soil, mud, and gravel for leveling along

24800-605: Was racially based and served the white settler community while excluding Africans; and in Mandate Palestine, Shamir claimed that British electric concessions to a Zionist-owned company deepened the economic disparities between Arabs and Jews. While electrification of cities and homes has existed since the late 19th century, about 840 million people (mostly in Africa) had no access to grid electricity in 2017, down from 1.2 billion in 2010. Vast gains in electrification were seen in

24960-400: Was so much safer than oil or gas that some companies were able to pay for the electricity with the insurance savings. In 1851, Charles Babbage stated: One of the inventions most important to a class of highly skilled workers (engineers) would be a small motive power - ranging perhaps from the force of from half a man to that of two horses, which might commence as well as cease its action at

25120-701: 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

25280-416: Was the potential leakage of diesel fuel, and divers had stopped the leak within a day. In 2007, as BART celebrated the 50th anniversary of its creation, it announced its plans for the next 50 years. Determining the current tunnel will be at its operational capacity by the year 2030, the agency has plans which include a new separate Transbay Tube beneath San Francisco Bay that would run parallel to and south of

25440-545: Was the world's first to have working light bulbs installed. The Lit & Phil Library in Newcastle , was the first public room lit by electric light, and the Savoy Theatre was the first public building in the world lit entirely by electricity. The first central station providing public power is believed to be one at Godalming , Surrey, UK, in autumn 1881. The system was proposed after the town failed to reach an agreement on

25600-440: Was to feed a carbon electrode by gravity and maintain the gap with a pair of electromagnets, one of which retracted the upper carbon after the arc was started and the second controlled a brake on the gravity feed. Arc lamps of the time had very intense light output – in the range of 4,000 candlepower (candelas) – and released a lot of heat, and they were a fire hazard, all of which made them inappropriate for lighting homes. In

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