121-590: The Regional Connector Transit Project constructed a 1.9-mile (3.1 km) light rail tunnel for the Los Angeles Metro Rail system in Downtown Los Angeles . It connected the A and E lines with the former L Line . The A and E lines previously both terminated at 7th Street/Metro Center station , coming from Long Beach and Santa Monica, respectively, while the L Line ran through Little Tokyo/Arts District to either Azusa or East Los Angeles . Now
242-695: 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
363-593: A bipartisan infrastructure bill with about $ 110 billion for roads and bridges. As of 2010, seat belt use is mandatory in all states except New Hampshire . Seat belt use is also mandatory in Washington, D.C. , the national capital, and the five inhabited U.S. territories . Greyhound Lines is the largest intercity bus company in the United States, with routes in all parts of the contiguous U.S. There are also many smaller regional bus companies, many of which use
484-591: A designation created for the legacy highway network in 1995, comprising 160,000 miles (256,000 kilometers) of roadway, a fraction of the total mileage of roads. The Interstate system serves nearly all major U.S. cities, often through the downtown areas, which triggered freeway and expressway revolts in the 1960s and 1970s. The distribution of many goods and services involves Interstate highways at some point. Residents of American cities commonly use urban Interstates to travel to their places of work. The vast majority of long-distance travel, whether for vacation or business,
605-449: 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
726-489: A loss of ridership. As the civil air transportation network of airports and other infrastructure expanded, air travel became more accessible to the general population. Technological advances ushered in the jet age , which increased airline capacity, while decreasing travel times and the cost of flights. The costs of flying rapidly decreased intercity rail ridership by the late 1960s to a point where railroads could no longer profitably operate networks of passenger trains. By
847-525: A new era of mobility in the United States. The early 20th century Lincoln Highway and other auto trails gave way in the 1920s to an early national highway system making the automobile the primary mode of travel for most Americans. Interurban rail service declined, followed by trolley cars due in part to the advent of motorized buses and the lack of dedicated rights-of-way but also by deliberate efforts to dismantle urban rail infrastructure. The scarcity of industrial materials during World War II slowed
968-461: 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,
1089-473: A result of aging infrastructure and poor road conditions. The United States continues to follow a method of attempting to resolve congestion by widening roadways. From 1993 to 2017, the nation's largest 100 urbanized areas added 42% more freeway lane milage, despite population growing by only 32%. However, this policy of widening roadways resulted in a 144% increase in congestion, due to the concept of induced demand . The trucking industry (also referred to as
1210-779: A similar study for the extension of the Red Line subway. In June 2007, the LACMTA Board approved the consultants to perform the Alternative Analysis and MIS, and in July 2007 the Alternatives Analysis was initiated. In November 2007, preliminary outreach meetings for the Alternative Analysis were held at Central Library and the Japanese American National Museum (JANM). The results from these meetings were presented to
1331-421: 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
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#17328523140301452-401: A technical feasibility assessment for a potential regional connector. This study focused on conceptual methods to provide a regional connector and to alleviate potential operational constraints. The 2004 staff study looked at the potential alignments that would not be entirely underground, due to funding constraints from the voter-approved 1998 Prop A ban on local county subway funding. Most of
1573-434: 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
1694-710: 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,
1815-432: 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
1936-491: 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. Major Investment Study Employment The vast majority of passenger travel in the United States occurs by automobile for shorter distances and airplane or railroad for longer distances. Most cargo in
2057-576: Is by the national road network; of these trips, about one-third (by the total number of miles driven in the country in 2003) utilize the Interstate system. In addition to the routes of the Interstate system, there are those of the U.S. highway system . These routes, which are unrelated to those of the National Highway System, are supplemented by State Highways , and the local roads of counties , municipal streets , and federal agencies, such as
2178-500: 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
2299-449: Is no single national flag airline ; passenger airlines in the United States have always been privately owned. There are over 200 domestic passenger and cargo airlines and a number of international carriers. The major international carriers of the United States are Delta Air Lines , American Airlines , and United Airlines . Low-cost carrier Southwest Airlines operates few international routes, but has grown its domestic operations to
2420-896: Is partly funded by the federal government but owned and maintained by individual state governments. There are a few private highways in the United States , which use tolls to pay for construction and maintenance. There are many local private roads , generally serving remote or insular residences. Passenger and freight rail systems, bus systems, water ferries, and dams may be under either public or private ownership and operation. Civilian airlines are all privately owned. Most airports are owned and operated by local government authorities, but there are also some private airports. The Transportation Security Administration has provided security at most major airports since 2001. The U.S. Department of Transportation and its divisions provide regulation, supervision, and funding for all aspects of transportation, except for customs, immigration, and security, which are
2541-487: 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
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#17328523140302662-563: Is shared between the state and federal governments, while the United States Coast Guard is the primary enforcer of law and security on U.S. waterways. Passenger transportation is dominated by a network of over 3.9 million miles of highways which is pervasive and highly developed by global standards. Passenger transportation is dominated by passenger vehicles (including cars , trucks , vans, and motorcycles ), which account for 86% of passenger-miles traveled. The remaining 14%
2783-401: 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
2904-515: 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
3025-673: 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
3146-429: 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
3267-632: The Accelerated Bridge Program in Massachusetts , but after some debate no increase in federal funding. The I-5 Skagit River bridge collapse in 2013, caused by a collision with an over-height truck , highlighted fracture critical bridges in which the failure of only one structural member will lead to complete collapse. According to the National Bridge Inventory , there are at least 600,000 bridges of 20 feet or more in length in
3388-533: The American economy by transporting large quantities of raw materials , works in process , and finished goods over land—typically from manufacturing plants to retail distribution centers. Trucks are also important to the construction industry, as dump trucks and portable concrete mixers are necessary to move the large amounts of rocks, dirt, concrete, and other construction material. Trucks in America are responsible for
3509-556: 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
3630-452: The Bureau of Indian Affairs . The five inhabited U.S. territories also have their own road networks. There are approximately 4,161,000 miles (6,696,000 km) of roads in the United States, 2,844,000 miles (4,577,000 km) paved and 1,317,000 miles (2,120,000 km) unpaved. State highways are constructed by each state, but frequently maintained by county governments aided by funding from
3751-636: The Civic Center ) was shifted slightly west toward Broadway , to take advantage of redevelopment efforts in the historic core. This option is generally fastest and has fewest impacts during operations, but it would have more construction impacts and higher costs. The following table summarizes key characteristics of each alternative: In September 2010, Metro published the Draft Environmental Impact Statement / Environmental Impact Report (Draft EIS/EIR). The report recommended adoption of
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3872-685: The Little Tokyo/Arts District station will be moved underground and across the street. One of the structures existed since at least 1898 and both played an important role in the cultural life of the Little Tokyo neighborhood for decades. By late 2017, one of the two tunnels had been completed; the second tunnel was completed in January 2018. Extra work and expense were required to work around century-old water and electric infrastructure beneath downtown Los Angeles. Metro had revised its estimate for
3993-464: 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
4114-797: 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
4235-466: 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
4356-565: The Toledo War between Ohio and Michigan in the 1830s. The disputed Erie Triangle was awarded to Pennsylvania, giving that state access to Lake Erie . Most of West Florida was given to Mississippi and Alabama to guarantee their access to the Gulf of Mexico . Development of the mid-western and southern states drained by the Mississippi River system ( Mississippi , Ohio and Missouri Rivers )
4477-725: The U.S. Environmental Protection Agency implemented revised emission standards for diesel trucks (reducing airborne pollutants emitted by diesel engines) which promises to improve air quality and public health. Within the United States: With adjacent countries: Each state has its own traffic code , although most of the rules of the road are similar for the purpose of uniformity, given that all states grant reciprocal driving privileges (and penalties ) to each other's licensed drivers. The United States has advanced air transportation infrastructure which utilizes approximately 5,000 paved runways. In terms of passenger traffic, 17 of
4598-665: 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
4719-591: 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
4840-654: The hours of service , which are regulations governing the driving hours of commercial drivers. These, and all other rules regarding the safety of interstate commercial driving, are issued by the Federal Motor Carrier Safety Administration (FMCSA). The FMCSA is also a division of the United States Department of Transportation (USDOT), which governs all transportation-related industries such as trucking, shipping , railroads , and airlines . Some other issues are handled by another branch of
4961-486: 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
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5082-412: The "Fully Underground LRT Alternative" (LRT 3 above). In October 2010, Metro staff reaffirmed this recommendation, but with the 5th/Flower station removed. The report cited concerns for the overall project cost and the proposed station's short distance from Metro Center/7th Street Station, a mere three blocks, which might not have met FTA funding standards. However, proponents of a 5th/Flower station cited
5203-689: 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
5324-638: 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
5445-687: 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 ;
5566-624: The 1990s there have been some small experiments with toll roads operated by private companies. After the collapse of the I-35W Mississippi River bridge in Minnesota in August 2007, the backlog of road and bridge maintenance across the country became an issue in transportation funding. The collapse prompted a tax increase in Minnesota to speed up bridge repairs, and action in other states, such as
5687-484: The 19th Century gradually reduced their presence. The rapid expansion of railroads brought the canal boom to a sudden end, providing a quick, scheduled and year-round mode of transportation that quickly spread to interconnect the states by the mid-19th century. During the industrialization of the United States after the Civil War , railroads, led by the transcontinental rail system in the 1860s, expanded quickly across
5808-410: The 46,000 mile (75,000 km) nationwide Interstate highway network. Changes by state initiative may be made with federal approval. A large number of expressways are actually government or privately operated toll roads in many East Coast and Midwestern states. West Coast freeways are generally free to users, which is the basis of their name, since freeways have no toll charged per use, although since
5929-685: The 5th/Flower station deleted as the Locally Preferred Alternative (LPA). The project staff will now conduct a final study of the LPA, which will culminate in a Final Environmental Impact Study/Environmental Impact Report (Final EIS/EIR). Measure R guarantees the Regional Connector $ 160 million for implementation. In February 2014, the federal government granted Metro $ 670 million in New Starts funds and $ 160 million in infrastructure loans for
6050-457: The A and E lines continue together through new stations at Grand Avenue Arts/Bunker Hill , Historic Broadway , and Little Tokyo/Arts District . From there, they diverge on the former L Line toward Azusa and East Los Angeles, respectively. The project provides a one-seat ride into the core of Downtown for passengers on those lines who previously needed to transfer, thus reducing or altogether eliminating many transfers of passengers traveling across
6171-568: The Final Environmental Impact Report was certified on April 26, 2012. Pre-construction on the project began in December 2012. The contract for heavy construction on the project was signed on July 9, 2014, and its official groundbreaking was held on September 30, 2014. Originally scheduled to open in 2020, but delayed due to construction and train testing difficulties, the project opened on June 16, 2023. The project's tunnels begin at
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#17328523140306292-491: The German Autobahn system. By 1945, after the end of World War II , nearly every city in America had at least one electric tram company providing intra-city transportation. There were an estimated 36,377 light rail vehicles in operation. Increased automobile ownership cut this number by 1/3 by 1965. The airline industry began to successfully compete with intercity rail as a result of government investment, which suffered
6413-513: The L Line and used parts of its route to reconfigure the A and E Lines into the following: Due to the restructuring of service, the A Line became the longest light rail line in the world at 49.5 miles (79.7 km), surpassing the 42 miles (68 km) Coast Tram in Belgium. It will become even longer upon completion of Phase 2B of the Foothill Extension when it opens in 2025. The connector
6534-691: 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
6655-469: The Regional Connector tunnel is built using the tunnel boring machine (TBM) construction method, though some sections (especially the locations of the three subway rail stations) use the cut-and-cover construction method with an emphasis on maintaining as much road access as possible during construction. Metro has an agreement with the Los Angeles Music Center to use the most advanced state of
6776-538: The Second Street Tunnel through Bunker Hill (between Hill and Figueroa Streets) or the Third Street Tunnel (between Hill and Flower Streets) to minimize costs, improve operating times and improve the feasibility of constructing the project. In July 2006, the LACMTA Board voted to approve funding and staff to initiate a Major Investment Study (MIS) for the Regional Connector in conjunction with approval of
6897-551: The U.S. is transported by, in descending order, railroad, truck, pipeline, or boat; air shipping is typically used only for perishables and premium express shipments. Transportation is the largest source of greenhouse gas emissions in the United States . The overwhelming majority of roads in the United States are owned and maintained by state and local governments. Federally maintained roads are generally found only on federal lands (such as national parks ) and at federal facilities (like military bases). The Interstate Highway System
7018-578: The USDOT, the Federal Highway Administration (FHWA). Developments in technology, such as computers, satellite communication , and the internet, have contributed to many improvements within the industry. These developments have increased the productivity of company operations, saved the time and effort of drivers, and provided new, more accessible forms of entertainment to men and women who often spend long periods of time away from home. In 2006,
7139-631: The United States and Canada rely more heavily on motorized transit over walking and bicycling with 86% of American workers commuting to work via private vehicle, costing an estimated additional $ 1500 per year commuting compared to Western European counterparts. Car ownership is on the decline but still 91% nationally. Car ownership is universal, except in the largest cities where extensive mass transit and railroad systems have been built, with lowest car ownership rates in New York City (44%), Washington, D.C. (62%), Boston (63%), Philadelphia (67%), San Francisco (69%), and Baltimore (69%). With
7260-452: The United States to serve industries and the growing cities. During the late 19th century, railroads often had built redundant routes to a competitor's road or built through sparsely populated regions that generated little traffic. These marginal rail routes survived the pricing pressures of competition, or the lack of revenue generated by low traffic, as long as railroads provided the only efficient economical way to move goods and people across
7381-535: The United States, all subject to deterioration in the absence of preventative maintenance. In December 2008, 72,868 bridges in the United States (12.1%) were categorized as "structurally deficient", representing an estimated $ 48 billion in repairs. President Barack Obama proposed $ 50 billion of spending on road and bridge repair, plus a national infrastructure bank, but Congress did not act on these proposals. President Donald Trump also failed to get infrastructure funding approved. In 2021, President Joe Biden signed
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#17328523140307502-525: 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
7623-422: The United States. In addition to the intercity passenger network running on Class I and II railroads, a large network of interurban ( trolley or "street running") rail lines extended out from the cities and interchanged passenger and freight traffic with the railroads and also provided competition. The advent of the automobile signaled the end of railroads as the predominant transportation for people and began
7744-691: The alignments were under Flower Street, surfacing between 5th Street and 1st Street and proceeding east to Alameda Street , connecting to the Eastside light rail corridor (now part of the Metro L Line ), and continuing either north toward Union Station and Azusa or east toward East Los Angeles . LACMTA staff analyzed at-grade street-running couplets, transit mall, elevated and hybrid subway /at-grade/elevated alignments along east-west streets such as Temple Street , First Street, Second Street and Third Street and utilizing available grade-separated infrastructure such as
7865-483: The art noise-suppression measures underneath 2nd Street where it passes Walt Disney Concert Hall and the Colburn School of Music . This commits Metro to use procedures to ensure that the rumble of trains does not intrude on the sound quality of recordings made in the venues or mar audiences' musical experience within this sensitive stretch of the tunnel. Two modest, one-story brick buildings had to be demolished since
7986-400: 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
8107-548: The building of canals to speed goods to market. One such prominent example was the Erie Canal . Numerous modes of transportation fought for supremacy throughout the Industrial revolution of the 19th century. Canals swiftly took the role of turnpikes, stagecoaches , and wagon routes, which in turn were shortly replaced by steam-powered riverboats . During this period, the advancement in transportation inspired many artists to display
8228-498: 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
8349-502: The delivery of overland mail, such as the Boston Post Road between New York City and Boston . Due to the distances between these population centers and the cost to maintain the roads, many highways in the late 18th century and early 19th century were private turnpikes . Other highways were mainly unimproved and impassable by wagon at least some of the year. Economic expansion in the late 18th century to early 19th century spurred
8470-564: The development of the extensive Eisenhower Interstate Highway System in the 1950s, both long distance trips and daily commutes were mostly by private automobile . This network was designed to exacting federal standards in order to receive federal funding. The system, as of 2010 , has a total length of 47,182 miles (75,932 km), making it the world's second longest after China 's, and the largest public works project in US history. The Interstate system joined an existing National Highway System ,
8591-422: The early 1970s almost all passenger rail operation and ownership had been transferred to various federal, municipal and state agencies. Freight railroads continued to decline as motor freight captured a significant portion of the less-than-carload business. This loss of business, when combined with the highly regulated operating environment and constrained pricing power , forced many railroads into receivership and
8712-409: 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
8833-441: 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
8954-515: The grand contrast from the past to the new. Taking a look at Samuel Colman 's work, one piece in particular, Storm King on the Hudson (1866) [1] displayed both the older sailboats and the grand steamboats that were overtaking the Hudson River . Access to water transportation shaped the geography of early settlements and boundaries. For example, the Erie Canal escalated the boundary dispute called
9075-405: 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
9196-533: The growth of automobile manufacturing briefly and contributed to the nation's declining rail network. In the 1950s, however, the United States renewed building a network of high-capacity, high-speed highways to link its vast territory. The most important element is the Interstate Highway system, first commissioned in the 1950s by President Dwight D. Eisenhower and modeled partly after the Italian autostrada and
9317-617: The high density of very large high-rise office buildings within one block of a 5th/Flower station and that such a station would relieve what is expected to be extreme pressure at Metro Center/7th Street (already experiencing pressure) once the E Line, then the Regional Connector are complete. At the Metro Board meeting in late October 2010, the Board certified the Draft EIS/EIR and accepted the staff recommendation of Fully Underground Alternative with
9438-654: The highest rate of per-capita vehicle ownership in the world, with 865 vehicles per 1,000 Americans. Bicycle usage is minimal with the American Community Survey reporting that bicycle commuting had a 0.61% mode share in 2012 (representing 856,000 American workers nationwide). Freight transportation is carried by a variety of networks. The largest percentage of US freight is carried by trucks (60%), followed by pipelines (18%), rail (10%), ship (8%), and air (0.01%). Other modes of transportation, such as parcels and intermodal freight accounted for about 3% of
9559-636: 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
9680-435: 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
9801-468: 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
9922-473: The largest freight transportation occupation, with approximately 2.83 million truck drivers. About 57.5 percent of these professional truck drivers operate heavy or tractor-trailer trucks and 28.2 percent drive light or delivery service trucks. According to Freight Facts and Figures 2015 , U.S. freight transportation system handled a record amount of freight in 2014. A daily average of approximately 55 million tons of freight valued at $ 49.3 billion moved across
10043-480: The late 18th century, overland transportation was by horse, while water and river transportation was primarily by sailing vessel. The United States population was centered on its Atlantic coast , with all major population centers located on a natural harbor or navigable waterway. Low population density between these centers resulted in a heavy reliance on coastwise and riverboat shipping. The first government expenditures on highway transportation were funded to speed
10164-607: 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
10285-401: The majority of freight movement over land, and are vital tools in the manufacturing, transportation, and warehousing industries. Large trucks and buses require a commercial driver's license (CDL) to operate. Obtaining a CDL requires extra education and training dealing with the special knowledge requirements and handling characteristics of such a large vehicle. Drivers of CMVs must adhere to
10406-639: The nationalization of several critical eastern carriers into the Consolidated Rail Corporation (Conrail). Deregulation of the railroads by the Staggers Act in 1980 created a regulatory environment more favorable to the economics of the railroad industry. In the 1990s, the increase in foreign trade and intermodal container shipping led to a revival of the freight railroads, which have effectively consolidated into two eastern and two western private transportation networks: Union Pacific and BNSF in
10527-451: The north end of 7th Street/Metro Center station , the previous terminal built in the early 1990s, and continue north under Flower Street. The line turns to run under 2nd Street and dives below the 2nd Street Tunnel and the B/D subway with clearances as low as 7 feet (2.1 m). In Little Tokyo, the line turns off 2nd to serve the replacement underground Little Tokyo/Arts District station before
10648-601: The northern terminus of the Blue Line and the eastern terminus of the Expo Line , which opened on April 28, 2012. All three build alternatives connected to the preexisting Gold Line at Alameda Street near Temple Street or 1st Street. On October 28, 2010, the LACMTA Board of Directors opted for a fully underground option, rejecting at-grade and underground emphasis alternatives. This route remains underground below Flower and 2nd Streets until northwest of 1st/Alameda. By that point,
10769-483: 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
10890-540: 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
11011-514: The package and cargo delivery market. The U.S. government's National Center for Health Statistics reported 33,736 motor vehicle traffic deaths in 2014. This exceeded the number of firearm deaths, which was 33,599 in 2014. In 2020 there was 115% more road fatalities in the US than in the European Union, or 53% less in the EU than in the US, with nearly 38,680 in the US, and nearly 18,800 in the EU. In
11132-455: The past decade, and despite the declining traffic volumes caused by the economic downturn, Americans still waste more than 2.8 billion US gallons (11 million cubic metres) of fuel each year as a result of traffic congestion. Motorists also waste 4.2 billion hours annually, or one full workweek per traveler. Moreover, it is estimated that drivers are wasting 6.9 billion hours per year or about 42 hours per driver in traffic congestion as
11253-546: The project completion to early 2023, more than two years after the original estimated completion date. In 2020, due to the COVID-19 pandemic and the subsequent state-mandated closings of local businesses and stay-at-home orders that resulted in reduced traffic, the city of Los Angeles was able to shut down some local roads, allowing Metro to accelerate construction. In April 2022, Metro completed all trackwork as well as station platforms and system guideways. Starting April 9, 2023,
11374-510: 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
11495-435: The project's final testing phase began. The A, E, and L Line trains ran through the newly built tunnel from Long Beach to Azusa and Santa Monica to East Los Angeles . The final work included station plaza, street restoration, and fencing construction. It opened on June 16, 2023. Tunnel A tunnel is an underground or undersea passageway. It is dug through surrounding soil, earth or rock, or laid under water, and
11616-422: The project. Pre-construction activities began in December 2012, with the start of the relocation of utility pipes. Major heavy construction was scheduled to begin in 2013, but was delayed by lawsuits, among other factors. The main contractor was finally issued a "Notice to Proceed" in early July 2014; the official groundbreaking for heavy construction on the project was held on September 30, 2014. Most sections of
11737-485: 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,
11858-555: The public in February 2008, including the descriptions of the eight route alternatives identified for analysis, narrowed down to two later in 2008. At the January 2009 Metro Board Meeting, the Regional Connector was approved and received funding to continue in the environmental study process (Draft EIS/EIR). The Alternatives Analysis yielded two LRT ( light rail ) build alternatives, plus the required "No Build" and "TSM" ( Transportation System Management ) options. A third LRT build alternative
11979-603: The region via Downtown Los Angeles. The project was implemented by the Los Angeles County Metropolitan Transportation Authority (Metro). It was given high priority by Metro in its long-range plan and had funding set aside for it in Measure R . The draft environmental impact statement was completed in September 2010, selection of a preferred alternative was completed in late October 2010, and
12100-437: The remainder. Air freight is commonly used only for perishables and premium express shipments. The difference in percentage of rail's share by ton-miles and by weight (10% vs 38%) is accounted for by the extreme efficiency of trains. A single railroad locomotive may pull fifty boxcars full of freight while a truck only pulls one. Trucks surpass trains in the weight category due their greater numbers, while trains surpass trucks in
12221-557: The responsibility of the U.S. Department of Homeland Security . Each state has its own Department of Transportation , which builds and maintains state highways, and depending upon the state, may either directly operate or supervise other modes of transportation. Aviation law is almost entirely the jurisdiction of the U.S. federal government , and automobile traffic laws are enacted and enforced by state and local authorities except on highways or roads on federal property or in unorganized territories . Economic jurisdiction over tidelands
12342-482: 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
12463-474: The route would have split into two branches. Each branch would then emerge from a tunnel – one heading north to Union Station, the other east to the Eastside. Metro added this alignment in February 2010, after receiving public input on the other two options. This option puts the connector underground beneath 1st/Alameda. The fourth new station (at 1st/Alameda southwest block) would replace the existing Little Tokyo/Arts District station. The third station (nearest
12584-463: The routes split to their own surface portals, connecting to former L Line tracks. The Regional Connector includes three stations. From northeast to southwest, the stations are: At previous points during planning and construction, Little Tokyo/Arts District was referred to as 1st St/Central; Historic Broadway as Los Angeles City Hall or 2nd Street/Broadway; and Grand Avenue Arts/Bunker Hill as Bunker Hill or 2nd Place/Hope Street. Metro discontinued
12705-528: 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
12826-497: The state, where such counties exist as governing entities in mostly every state outside of the northeast . Counties construct and maintain all remaining roads outside cities, except in private communities. Local, unnumbered roads are often constructed by private contractors to local standards, then maintenance is assumed by the local government. All federal highways are maintained by state governments, although they receive federal aid to build and maintain freeways signed as part of
12947-438: The terminal and booking facilities provided by Greyhound. Intercity bus is, in most cases, the least expensive way to travel long distances in the United States. Traffic congestion, especially at rush hour, is often considered a problem in many of the country's larger cities. A 2009 study claimed that traffic congestion costs the United States almost $ 87.2 billion. The economic costs of traffic congestion have increased 63% over
13068-434: The ton-miles category due to the vast distances they travel carrying large amounts of freight. Usually cargo, apart from petroleum and other bulk commodities, is imported in containers through seaports, then distributed by road and rail. The quasi-governmental United States Postal Service has a monopoly on letter delivery (except for express services) but several large private companies such as FedEx and UPS compete in
13189-423: The transportation or logistics industry) involves the transport and distribution of commercial and industrial goods using commercial motor vehicles (CMV). In this case, CMVs are most often trucks ; usually semi trucks , box trucks , or dump trucks . A truck driver (commonly referred to as a "trucker") is a person who earns a living as the driver of a CMV. The trucking industry provides an essential service to
13310-471: The transportation system in 2014 to meet the needs of the nation's 122.5 million households, 7.5 million business establishments, and 90,056 Government units. Wartime expediency encouraged long distance pipeline transport of petroleum and natural gas, which was greatly expanded in the middle 20th century to take over most of the domestic long-haul market. In comparison to some parts of the Western world , both
13431-400: 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,
13552-428: 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
13673-515: The west, and CSX and Norfolk Southern in the east. Canadian National Railway took over the Illinois Central route down the Mississippi River valley. In 2014, freight transportation establishments serving for-hire transportation and warehousing operations employed nearly 4.6 million workers and comprised 9.5 percent of the Nation's economic activity as measured by GDP. Truck driving is by far
13794-468: The world's 30 busiest airports in 2004 were in the United States, including the world's busiest, Hartsfield-Jackson Atlanta International Airport . In terms of cargo, in the same year, twelve of the world's thirty busiest airports were in the United States, including the world's busiest, Memphis International Airport . Private aircraft are also used for medical emergencies, government agencies, large businesses, and individuals, see general aviation . There
13915-410: Was accelerated by the introduction of steamboats on these rivers in the early 19th Century. These three rivers ( among others ) also form the borders of several states. Prior to the introduction of steamboats, transit upstream was impractical because of strong currents on parts of these waterways. Steamboats provided both passenger and freight transportation until the development of railroads later in
14036-405: Was added in February 2010, at the request of Little Tokyo stakeholders (including property, business, and homeowners). The operational intent of the project was to allow through running of service between the four corridors (Blue Line corridor, Expo corridor, Gold Pasadena corridor, and Gold Eastside corridor). All three build alternatives began at 7th St/Metro Center station , which was previously
14157-566: 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
14278-612: Was envisioned as early as 1984 when planning and building the Metro Blue Line and restudied with a through connection in the Pasadena Light Rail Corridor studies in 1989. LACMTA originally envisioned the Blue Line running through Downtown L.A. to Union Station and onward to Pasadena with potential future lines to the northwest ( Burbank / Glendale ) and to the south and west ( Exposition Park / Santa Monica ). The connector
14399-467: Was handled by planes , trains , and buses . Public transit use is highly concentrated in large older cities, with only six above 25% and only New York City above 50% of trips on transit. Airlines carry almost all non-commuter intercity traffic, except the Northeast Corridor where Amtrak carries more than all airlines combined. The world's second largest automobile market, the United States has
14520-697: Was not completed due to lack of funds and realignment of the Red Line Eastside Extension, which later became an extension of the Pasadena Gold Line (the Gold Line was renamed the L line in 2019). The connector was formally studied for the first time as a stand-alone project in a Major Investment Study in 1992–1993, in preparation of the Long Range Transportation Plan. The project was revived in 2004, when LACMTA staff initiated
14641-701: 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
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