Misplaced Pages

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89-496: Black Thunder's dragline excavator Ursa Major is the biggest working dragline in North America and the third largest ever made. It produces enough coal to load up to 20-25 trains per day. Draglines are not used to dig coal, but only strip overburden . Black Thunder operates six draglines. Coal is excavated by power shovels and loaded into haul trucks . In 1974, exploration geologist Lewis R. Ladwig drilled exploratory holes on

178-429: A Tarong BE1370. Since draglines are typically large, complicated and very expensive, training new operators can be a tricky process. In the same way that flight simulators have developed to train pilots, mining simulator software has been developed to assist new operators in learning how to control the machines. UDD stands for universal dig-dump . It represents the first fundamental change to draglines for almost

267-400: A road use tax , is payable on some vehicles used on the public road. The definition of a road depends on the definition of a highway; there is no formal definition for a highway in the relevant Act. A 1984 ruling said "the land over which a public right of way exists is known as a highway; and although most highways have been made up into roads, and most easements of way exist over footpaths,

356-411: A single carriageway road is converted into dual carriageway by building a second separate carriageway alongside the first, it is usually referred to as duplication , twinning or doubling . The original carriageway is changed from two-way to become one-way, while the new carriageway is one-way in the opposite direction. In the same way as converting railway lines from single track to double track ,

445-411: A "carbon bomb," a fossil fuel project that would result in more than one gigaton of carbon dioxide emissions if fully extracted and burnt. Dragline excavator A dragline excavator is a heavy-duty excavator used in civil engineering and surface mining . It was invented in 1904, and presented an immediate challenge to the steam shovel and its diesel and electric powered descendant,

534-457: A 25 to 50 millimeter hole through the pavement into the sub-base with a dry-bit roto-hammer . Next, a two-part epoxy is poured into the hole – dyed for visual clarity. Once the epoxy hardens, technicians drill through the hole. If a void is present, the epoxy will stick to the core and provide physical evidence. Common stabilization materials include pozzolan -cement grout and polyurethane. The requirements for slab stabilization are strength and

623-450: A 310 feet (94 m) boom, and weighed 13,500 tons. The largest walking dragline produced as of 2014 was Joy Global ’s digital AC drive control P&H 9020XPC, which has a bucket capacity of 110–160 cu yd (84–122 m ) and boom lengths ranging from 325–425 ft (99–130 m); working weights vary between 7,539 and 8,002 tons. Draglines fall into two broad categories: those that are based on standard, lifting cranes, and

712-605: A May 2009 report by the American Association of State Highway and Transportation Officials (AASHTO) and TRIP – a national transportation research organization – driving on rough roads costs the average American motorist approximately $ 400 a year in extra vehicle operating costs. Drivers living in urban areas with populations more than 250,000 are paying upwards of $ 750 more annually because of accelerated vehicle deterioration, increased maintenance, additional fuel consumption , and tire wear caused by poor road conditions. When

801-455: A century, since the invention of the 'miracle hitch'. Instead of using two ropes (the hoist rope and the drag rope) to manipulate the bucket, a UDD machine uses four ropes, two hoist and two drag. This allows the dragline operator to have much greater selectivity in when to pick up the bucket, and in how the bucket may be dumped. UDD machines generally have higher productivity than a standard dragline, but often have greater mechanical issues. Within

890-728: A company also associated with drainage pumping engines. Electric drive systems were only used on the larger mining machines, most modern machines use a diesel-hydraulic drive, as machines are seldom in one location long enough to justify the cost of installing a substation and supply cables. The basic mechanical technology of draglines, unlike that of most equipment used in earth-moving, has remained relatively unchanged in design and control functions for almost 100 years. Some advances, however, have been made (such as hydraulic, then electro-hydraulic, controls (including joysticks ) and using simulation software to train new operators), are being pursued (such as improved automation systems), or are arguable as

979-521: A controlling interest and the joint company became known as Bucyrus-Monighan until the formal merger in 1946. The first walking dragline excavator in the United Kingdom was used at the Wellingborough iron quarry in 1940. Ransomes & Rapier was founded in 1869 by four engineers to build railway equipment and other heavy works. In 1914 they started building two small steam shovels as a result of

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1068-411: A customer request. The rope-operated crowd system they built for this was patented and later sold to Bucyrus. After WWI, demand for excavators increased and in 1924 they reached an agreement to build Marion draglines from 1 to 8 cubic yards capacity. In 1927, they built Type-7 1-yard and Type-460 1.5-yard models. The deal to build Marion machines ended in 1936. R&R began building their own designs with

1157-419: A double-wheeled, steel roller to insert the rod to the desired depth. After inserting the backer rod, the sealant is placed into the joint. There are various materials to choose for this method including hot pour bituminous liquid, silicone and preformed compression seals. Careful design and construction of roads can increase road traffic safety and reduce the harm (deaths, injuries, and property damage) on

1246-556: A few diesel-electric excavators rather over 1/10th its size, the largest in Europe in the 1960s at 1400-1800 tons. One, named SUNDEW , was used in a quarry from 1957 to 1974. After its working life at the first site in Rutland wrapped it walked 13 miles (21 km) in 9 weeks to Corby , where it continued on till being scrapped from January to June 1987. Smaller draglines were also commonly used before hydraulic excavators came into common use,

1335-569: A large dragline bucket system is shown below. The dragline was invented in 1904 by John W. Page (as a partner of the firm Page & Schnable Contracting) for use in digging the Chicago Canal . By 1912, Page realized that building draglines was more lucrative than contracting, so he created the Page Engineering Company to build draglines. Page built its first crude walking dragline in 1923. These used legs operated by rack and pinion on

1424-413: A major two-level (and at one point, three-level) roadway in the downtown area, are being rebuilt with a designed service life of 100 years. Virtually all roads require some form of maintenance before they come to the end of their service life. Pro-active agencies use pavement management techniques to continually monitor road conditions and schedule preventive maintenance treatments as needed to prolong

1513-533: A proper elliptical motion and was used until 1988. Page modernized its draglines further with the 700 series in 1954. Page's largest dragline was the Model 757 delivered to the Obed Mine near Hinton, Alberta in 1983. It featured a 75-yard bucket on a 298-foot boom and an operating weight of 4,500 tons. In 1988, Harnischfeger Corporation ( P&H Mining Equipment ) purchased Page Engineering Company. Harnischfeger Corporation

1602-428: A road as "a line of communication (travelled way) using a stabilized base other than rails or air strips open to public traffic, primarily for the use of road motor vehicles running on their own wheels", which includes "bridges, tunnels, supporting structures, junctions, crossings, interchanges, and toll roads, but not cycle paths". The Eurostat , ITF and UNECE Glossary for Transport Statistics Illustrated defines

1691-494: A road as a "Line of communication (traveled way) open to public traffic, primarily for the use of road motor vehicles, using a stabilized base other than rails or air strips. [...] Included are paved roads and other roads with a stabilized base, e.g. gravel roads. Roads also cover streets, bridges, tunnels, supporting structures, junctions, crossings and interchanges. Toll roads are also included. Excluded are dedicated cycle lanes." The 1968 Vienna Convention on Road Traffic defines

1780-494: A road as the entire surface of any way or street open to public traffic. In urban areas roads may diverge through a city or village and be named as streets, serving a dual function as urban space easement and route. Modern roads are normally smoothed, paved, or otherwise prepared to allow easy travel . Part 2, Division 1, clauses 11–13 of the National Transport Commission Regulations 2006 defines

1869-519: A road in Australia as 'an area that is open to or used by the public and is developed for, or has as one of its main uses, the driving or riding of motor vehicles.' Further, it defines a shoulder (typical an area of the road outside the edge line, or the curb) and a road-related area which includes green areas separating roads, areas designated for cyclists and areas generally accessible to the public for driving, riding or parking vehicles. In New Zealand,

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1958-565: A separate frame that lifted the crane. The body was then pulled forward by chain on a roller track and then lowered again. Page developed the first diesel engines exclusively for dragline application in 1924. Page also invented the arched dragline bucket, a design still commonly used today by draglines from many other manufacturers, and in the 1960s pioneered an archless bucket design. With its walking mechanism badly behind that of competitor Monighan (see below), Page updated their mechanism to an eccentric drive in 1935. This much improved mechanism gave

2047-481: A simple single-crank mechanism in 1939. Its largest dragline was the 8950 sold to Amax Coal Company in 1973. It featured a 150-cubic yard bucket on a 310-foot boom and weighed 7,300 tons. Marion was acquired by Bucyrus in 1997. Bucyrus Foundry and Manufacturing Company entered the dragline market in 1910 with the purchase of manufacturing rights for the Heyworth-Newman dragline excavator. Their "Class 14" dragline

2136-464: A step forward (as is "universal dig-dump" ( UDD )): Researchers at CSIRO in Australia have a long-term research project into automating draglines. Mining automation teams at QCAT, a CSIRO division; have been developing the automation technology since 1994. Automated systems include cruise control and Digital Terrain Mapping . Working solutions include the proof-of-concept dragline swing cruise control on

2225-448: A walking dragline of 31-yard bucket capacity. HEC makes up to a 44-yard bucket. For comparison, this would be comparable to Caterpillar's Small Draglines 8000 series with a 42-yard bucket. HEC has supplied fifteen draglines to the Indian mining industry. In a typical cycle of excavation, the bucket is positioned above the material to be excavated. The bucket is then lowered and the dragrope

2314-432: Is 40 years for new bitumen and concrete pavement. Maintenance is considered in the whole life cost of the road with service at 10, 20 and 30-year milestones. Roads can be and are designed for a variety of lives (8-, 15-, 30-, and 60-year designs). When pavement lasts longer than its intended life, it may have been overbuilt, and the original costs may have been too high. When a pavement fails before its intended design life,

2403-418: Is a long-lived story that, back in the 1970s, if all seven draglines at Peak Downs Mine (a very large BHP coal mine in central Queensland , Australia) turned simultaneously, they would black out all of North Queensland . However even now, if they have been shut down, they are always restarted one at a time due to the immense power requirements of startup. In all but the smallest of draglines, movement

2492-433: Is a non-destructive method of solving this problem and is usually employed with other concrete pavement restoration methods including patching and diamond grinding. The technique restores support to concrete slabs by filing small voids that develop underneath the concrete slab at joints, cracks or the pavement edge. The process consists of pumping a cementitious grout or polyurethane mixture through holes drilled through

2581-406: Is accomplished by "walking" using feet or pontoons , as caterpillar tracks place too much pressure on the ground, and have great difficulty under the immense weight of the dragline. Maximum speed is only at most a few metres per minute, since the feet must be repositioned for each step. If travelling medium distances (about 30–100 km), a special dragline carrier can be brought in to transport

2670-487: Is also common. Some road fixtures such as road signs and fire hydrants are designed to collapse on impact. Light poles are designed to break at the base rather than violently stop a car that hits them. Highway authorities may also remove larger trees from the immediate vicinity of the road. During heavy rains, if the elevation of the road surface is not higher than the surrounding landscape, it may result in flooding. Speed limits can improve road traffic safety and reduce

2759-485: Is another common procedure used to locate voids. It is recommended to do this testing at night as during cooler temperatures, joints open, aggregate interlock diminishes and load deflections are at their highest. Ground penetrating radar pulses electromagnetic waves into the pavement and measures and graphically displays the reflected signal. This can reveal voids and other defects. The epoxy/core test, detects voids by visual and mechanical methods. It consists of drilling

Black Thunder Coal Mine - Misplaced Pages Continue

2848-418: Is discovered it is removed, moisture content is managed and replaced with standard fill compacted to meet the design requirements (generally 90–95% relative compaction). Blasting is not frequently used to excavate the roadbed as the intact rock structure forms an ideal road base. When a depression must be filled to come up to the road grade the native bed is compacted after the topsoil has been removed. The fill

2937-400: Is erected on site is commonly used in strip-mining operations to remove overburden above coal and more recently for oil sands mining. The largest heavy draglines are among the largest mobile land machines ever built, weighing up to 13,500 tons, while the smallest and most common of the site-erected type weigh around 8,000 tons. A dragline bucket system consists of a large bucket which

3026-559: Is limited by the length of rope the dragline can utilize. Inherent with their construction, a dragline is most efficient excavating material below the level of their base. While a dragline can dig above itself, it does so inefficiently and is not suitable to load piled up material (as a rope shovel or wheel loader can). Despite their limitations, and their extremely high capital cost, draglines remain popular with many mines, due to their reliability, and extremely low waste removal cost. The coal mining dragline known as Big Muskie , owned by

3115-451: Is made by the "compacted layer method" where a layer of fill is spread then compacted to specifications, under saturated conditions. The process is repeated until the desired grade is reached. General fill material should be free of organics , meet minimum California bearing ratio (CBR) results and have a low plasticity index . The lower fill generally comprises sand or a sand-rich mixture with fine gravel, which acts as an inhibitor to

3204-564: Is primarily due to environmental effects such as frost heaves , thermal cracking and oxidation often contribute, however accumulated damage from vehicles also contributes. According to a series of experiments carried out in the late 1950s, called the AASHO Road Test , it was empirically determined that the effective damage done to the road is roughly proportional to the fourth power of axle weight . A typical tractor-trailer weighing 80,000 pounds (36.287 t ) with 8,000 pounds (3.629 t) on

3293-406: Is so great that they have a direct connection to the high-voltage grid at voltages of between 6.6 and 22 kV. A typical dragline weighing 4000 to 6000 tons, with a 55-cubic-metre bucket, can use up to 6 megawatts during normal digging operations. Because of this, many (possibly apocryphal ) stories have been told about the blackout-causing effects of mining draglines. For instance, there

3382-517: Is some ambiguity between the terms highway and road . For the purposes of the English law , Highways Act 1980 , which covers England and Wales but not Scotland or Northern Ireland , road is "any length of highway or of any other road to which the public has access, and includes bridges over which a road passes". This includes footpaths, bridleways and cycle tracks, and also road and driveways on private land and many car parks. Vehicle Excise Duty ,

3471-446: Is suspended from a large truss -like boom (or mast) with wire ropes . The bucket is maneuvered by means of a number of ropes and chains. The hoist rope, powered by large diesel or electric motors , supports the bucket and hoist-coupler assembly from the boom. The dragrope is used to draw the bucket assembly horizontally. By skillful maneuver of the hoist and the dragropes the bucket is controlled for various operations. A schematic of

3560-410: Is taken to preserve reference Benchmarks Roads are designed and built for primary use by vehicular and pedestrian traffic. Storm drainage and environmental considerations are a major concern. Erosion and sediment controls are constructed to prevent detrimental effects. Drainage lines are laid with sealed joints in the road easement with runoff coefficients and characteristics adequate for

3649-801: Is the largest producer of coal in the US. The mine was opened in 1977, and operated by ARCO Coal until it was acquired in 1998 by Arch Coal . For most of its existence, Black Thunder has been the largest mine in the country (by production), but it was surpassed by the nearby North Antelope Rochelle Mine . North Antelope Rochelle was created after Peabody Energy purchased the Rochelle mine adjacent to their North Antelope Mine, and consolidated operations. Arch Coal, Inc. announced on March 9, 2009 that it has agreed to purchase Rio Tinto's Jacobs Ranch mine adjoining Black Thunder, which resulted in Black Thunder once again becoming

Black Thunder Coal Mine - Misplaced Pages Continue

3738-546: Is the native material underneath a constructed road. Road construction requires the creation of an engineered continuous right-of-way or roadbed , overcoming geographic obstacles and having grades low enough to permit vehicle or foot travel , and may be required to meet standards set by law or official guidelines. The process is often begun with the removal of earth and rock by digging or blasting, construction of embankments , bridges and tunnels , and removal of vegetation (this may involve deforestation ) and followed by

3827-414: Is then drawn so that the bucket is dragged along the surface of the material. The bucket is then lifted by using the hoist rope . A swing operation is then performed to move the bucket to the place where the material is to be dumped. The dragrope is then released causing the bucket to tilt and empty. This is called a dump operation. On crane-type draglines, the bucket can also be 'thrown' by winding up to

3916-559: Is usually stripped and stockpiled nearby for rehabilitation of newly constructed embankments along the road. Stumps and roots are removed and holes filled as required before the earthwork begins. Final rehabilitation after road construction is completed will include seeding, planting, watering and other activities to reinstate the area to be consistent with the untouched surrounding areas. Processes during earthwork include excavation, removal of material to spoil, filling, compacting, construction and trimming. If rock or other unsuitable material

4005-588: The Jacobs Ranch Mine - and its average 38 million tons per year - into the Black Thunder's annual production. With the acquisition of Jacobs Ranch Mine, Black Thunder is now the world's top coal producer. In 2011, the America Revealed "Electric Nation" episode aired on PBS and features Thunder Basin's Black Thunder coal mine. Black Thunder was reported to have mined 101.2 million tons of coal in 2014. The mine produced 62.2 million tons of coal in 2022, and

4094-406: The land zoning and storm water system. Drainage systems must be capable of carrying the ultimate design flow from the upstream catchment with approval for the outfall from the appropriate authority to a watercourse , creek , river or the sea for drainage discharge. A borrow pit (source for obtaining fill, gravel, and rock) and a water source should be located near or in reasonable distance to

4183-514: The open pit mining industry costs approximately US$ 50–100 million. A typical bucket has a volume ranging from 40 to 80 cubic yards (30 to 60 cubic metres), though extremely large buckets have ranged up to 220 cubic yards (168 cubic meters). The length of the boom ranges from 45 to 100 metres (148 to 328 ft). In a single cycle, it can move up to 450 tons of material. Most mining draglines are not diesel-powered like most other mining equipment. Their power consumption on order of several megawatts

4272-455: The power shovel . Much more efficient than even the largest of the latter, it enjoyed a heyday in extreme size for most of the 20th century, first becoming challenged by more efficient rotary excavators in the 1950s, then superseded by them on the upper end from the 1970s on. The largest ever walking dragline was Big Muskie , a Bucyrus-Erie 4250-W put online in 1969 that swung a 220 cu yd (170 m ), 325 ton capacity bucket, had

4361-529: The 800 ton 650-B which used a 15-yard bucket. Bucyrus' largest dragline was Big Muskie built for the Ohio Coal Company in 1969. This machine featured a 220-yard bucket on a 450-foot boom and weighed 14,500 tons. Bucyrus was itself acquired by heavy equipment and diesel engine maker, Caterpillar, in 2011. Caterpillar's largest dragline is the 8750 with a 169-yard bucket, 435-foot boom, and 8,350 ton weight. The market for draglines began shrinking rapidly after

4450-567: The Central Ohio Coal Company (a division of American Electric Power ), was the world's largest mobile earth-moving machine, weighing 13,500 tons and standing nearly 22 stories tall. It operated in Muskingum County , in the U.S. state of Ohio from 1969 to 1991, and derived power from a 13,800 volt electrical supply. It was dismantled for $ 700,000 worth of recycled metal in 1999. The British firm of Ransomes & Rapier produced

4539-624: The Jacob sheep ranch. He was working for ARCO. He discovered the coal reserves of the basin. In 2009, the America's Power Factuality Tour stopped at the Black Thunder Coal Mine to report on its role in generating electricity in the US. In 2010, the Black Thunder Mine produced an estimated 115 million tons of coal, an increase of 34 million tons over 2009. The increase was a result of merging

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4628-535: The Monighan Machine Company. In 1913, a Monighan engineer named Oscar Martinson invented the first walking mechanism for a dragline. The device, known as the Martinson Tractor, was installed on a Monighan dragline, creating the first walking dragline. This gave Monighan a significant advantage over other draglines and the company prospered. The cam mechanism was further improved in 1925 by eliminating

4717-520: The Type-4120 followed by the 4140 of 3.5 cubic yards. In 1958 the Ramsomes & Rapier division was sold to Newton, Chambers & Co. of Sheffield, which was combined with their NCK Crane & Excavator division. This became NCK-Rapier. The walking dragline division of NCK-Rapier was acquired by Bucyrus in 1988. The Marion Power Shovel Company (established in 1880) built its first walking dragline with

4806-422: The ability to flow into or expand to fill small voids. Colloidal mixing equipment is necessary to use the pozzolan-cement grouts. The contractor must place the grout using a positive-displacement injection pump or a non-pulsing progressive cavity pump. A drill is also necessary but it must produce a clean hole with no surface spalling or breakouts. The injection devices must include a grout packer capable of sealing

4895-521: The average US motorist pays about $ 335/year. In contrast, the average motorist pays about $ 171/year in road maintenance taxes (based on 600 gallons/year and $ 0.285/gallon tax). Distress and serviceability loss on concrete roads can be caused by loss of support due to voids beneath the concrete pavement slabs. The voids usually occur near cracks or joints due to surface water infiltration . The most common causes of voids are pumping, consolidation, subgrade failure and bridge approach failure. Slab stabilization

4984-428: The boom of the 1960s and 1970s which led to more mergers. P&H's acquisition of Page in 1988 along with Bucyrus' acquisition of Ransomes & Rapier in 1988 and Marion in 1997 cut the number of worldwide suppliers of heavy draglines by more than half. Today, P&H and Caterpillar are the only remaining manufacturers of large draglines. Heavy Engineering Corporation Limited was the first Indian company to manufacture

5073-538: The definition of a road is broad in common law where the statutory definition includes areas the public has access to, by right or not. Beaches, publicly accessible car parks and yards (even if privately owned), river beds, road shoulders (verges), wharves and bridges are included. However, the definition of a road for insurance purposes may be restricted to reduce risk. In the United Kingdom The Highway Code details rules for "road users", but there

5162-465: The design structural capacity, stop erosion or eliminate faulting. It does, however, restore the slab support, therefore, decreasing deflections under the load. Stabilization should only be performed at joints and cracks where the loss of support exists. Visual inspection is the simplest manner to find voids. Signs that repair is needed are transverse joint faulting, corner breaks and shoulder drop off and lines at or near joints and cracks. Deflection testing

5251-417: The drag chains for the shoes and changing to a cam wheel running in an oval track. This gave the shoe a proper elliptical motion. The first dragline using the new mechanism was the 3-W available in 1926. So popular were these machines that the name Monighan became a generic term for dragline. In the early 1930s, Bucyrus-Erie began purchasing shares of Monighan stock with Monighan's approval. Bucyrus purchased

5340-415: The dragline. Above that distance, disassembly is generally required. But mining draglines due to their reach can work a large area from one position and do not need to constantly move along the face like smaller machines. The primary limitations of draglines are their boom height and boom length, which limits where the dragline can dump the waste material. Another primary limitation is their dig depth, which

5429-441: The first pathways were the trails made by animals has not been universally accepted; in many cases animals do not follow constant paths. Some believe that some roads originated from following animal trails. The Icknield Way may exemplify this type of road origination, where human and animal both selected the same natural line. By about 10,000 BC human travelers used rough roads/pathways. In transport engineering , subgrade

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5518-416: The functional condition of the road while reducing the need for routing maintenance, leading to extended service life without increasing structural capacity. Older concrete pavements that develop faults can be repaired with a dowel bar retrofit , in which slots are cut in the pavement at each joint, and dowel bars are placed in the slots, which are then filled with concrete patching material. This can extend

5607-464: The growth of plants or other vegetable matter. The compacted fill also serves as lower-stratum drainage. Select second fill ( sieved ) should be composed of gravel , decomposed rock or broken rock below a specified particle size and be free of large lumps of clay . Sand clay fill may also be used. The roadbed must be "proof rolled" after each layer of fill is compacted. If a roller passes over an area without creating visible deformation or spring

5696-533: The heavy units which have to be built on-site. Most crawler cranes, with an added winch drum on the front, can act as a dragline. These units (like other cranes) are designed to be temporarily dismantled and transported over the road on flatbed trailers. Draglines used in civil engineering are of this smaller, crane type. These are used for road , port construction, pond and canal dredging, and as pile driving rigs. These types are built by crane manufacturers such as Link-Belt and Hyster . The much larger type which

5785-404: The highway system from traffic collisions. On neighborhood roads traffic calming , safety barriers , pedestrian crossings and cycle lanes can help protect pedestrians, cyclists, and drivers. Lane markers in some countries and states are marked with Cat's eyes or Botts dots. Botts dots are not used where it is icy in the winter, because frost and snowplows can break the glue that holds them to

5874-580: The hole. The injection device must also have a return hose or a fast-control reverse switch, in case workers detect slab movement on the uplift gauge. The uplift beam helps to monitor the slab deflection and has to have sensitive dial gauges. Also called joint and crack repair, this method's purpose is to minimize infiltration of surface water and incompressible material into the joint system. Joint sealants are also used to reduce dowel bar corrosion in concrete pavement restoration techniques. Successful resealing consists of old sealant removal, shaping and cleaning

5963-447: The jib and then releasing a clutch on the drag cable. This would then swing the bucket like a pendulum . Once the bucket had passed the vertical, the hoist cable would be released thus throwing the bucket. On smaller draglines, a skilled operator could make the bucket land about one-half the length of the jib further away than if it had just been dropped. On larger draglines, this is not a common practice. A large dragline system used in

6052-475: The largest mine in the world. The operator claims that "Black Thunder's active mine footprint comprises less than 1/4000th of Wyoming's land area", i.e. up to approximately 25 square miles (60 square km), but reclaimed land and as yet undisturbed areas are not included in this figure and much larger. In 2022, a team of researchers in a paper published in Energy Policy identified the Black Thunder coal mine as

6141-404: The laying of pavement material. A variety of road building equipment is employed in road building. After design, approval , planning , legal, and environmental considerations have been addressed alignment of the road is set out by a surveyor . The radii and gradient are designed and staked out to best suit the natural ground levels and minimize the amount of cut and fill. Great care

6230-473: The life of the concrete pavement for 15 years. Failure to maintain roads properly can create significant costs to society. A 2009 report released by the American Association of State Highway and Transportation Officials estimated that about 50% of the roads in the US are in bad condition, with urban areas worse. The report estimates that urban drivers pay an average of $ 746/year on vehicle repairs while

6319-609: The lifespan of their roads. Technically advanced agencies monitor the road network surface condition with sophisticated equipment such as laser/inertial profilometers . These measurements include road curvature , cross slope , asperity , roughness , rutting and texture . Software algorithms use this data to recommend maintenance or new construction. Maintenance treatments for asphalt concrete generally include thin asphalt overlays, crack sealing, surface rejuvenating, fog sealing, micro milling or diamond grinding and surface treatments . Thin surfacing preserves, protects and improves

6408-997: The mining industry, there is still much debate as to whether UDD improvements justify their costs. Road construction A road is a thoroughfare for the conveyance of traffic that mostly has an improved surface for use by vehicles (motorized and non-motorized) and pedestrians. Unlike streets , whose primary function is to serve as public spaces, the main function of roads is transportation. There are many types of roads , including parkways , avenues , controlled-access highways (freeways, motorways, and expressways), tollways , interstates , highways , thoroughfares , and local roads. The primary features of roads include lanes , sidewalks (pavement), roadways (carriageways), medians , shoulders , verges , bike paths (cycle paths), and shared-use paths . Historically many roads were simply recognizable routes without any formal construction or some maintenance. The Organization for Economic Co-operation and Development (OECD) defines

6497-515: The new carriageway is not always constructed directly alongside the existing carriageway. Roads that are intended for use by a particular mode of transport can be reallocated for another mode of transport, i.e. by using traffic signs . For instance, in the ongoing road space reallocation effort, some roads (particularly in city centers) which are intended for use by cars are increasingly being repurposed for cycling and/or walking . Like all structures, roads deteriorate over time. Deterioration

6586-466: The number of road traffic casualties from traffic collisions . In their World report on road traffic injury prevention report, the World Health Organization (WHO) identify speed control as one of various interventions likely to contribute to a reduction in road casualties. Road conditions are the collection of factors describing the ease of driving on a particular stretch of road, or on

6675-506: The owner may have excessive repair and rehabilitation costs. Some asphalt pavements are designed as perpetual pavements with an expected structural life in excess of 50 years. Many asphalt pavements built over 35 years ago, despite not being specifically designed as a perpetual pavement, have remained in good condition long past their design life. Many concrete pavements built since the 1950s have significantly outlived their intended design lives. Some roads like Chicago 's Wacker Drive ,

6764-418: The pavement performance, reduce construction costs and decrease maintenance. The completed roadway is finished by paving or left with a gravel or other natural surface. The type of road surface is dependent on economic factors and expected usage. Safety improvements such as traffic signs , crash barriers , raised pavement markers and other forms of road surface marking are installed. According to

6853-569: The presence or absence of a made road has nothing to do with the distinction. Another legal view is that while a highway historically included footpaths , bridleways , driftways, etc., it can now be used to mean those ways that allow the movement of motor vehicles , and the term rights of way can be used to cover the wider usage. In the United States, laws distinguish between public roads , which are open to public use, and private roads , which are privately controlled. The assertion that

6942-418: The reservoir, installing the backer rod and installing the sealant. Sawing, manual removal, plowing and cutting are methods used to remove the old sealant. Saws are used to shape the reservoir. When cleaning the reservoir, no dust, dirt or traces of old sealant should remain. Thus, it is recommended to water wash, sand-blast and then air blow to remove any sand, dirt or dust. The backer rod installation requires

7031-494: The road conditions". Specific aspects of road conditions can be of particular importance for particular purposes. For example, for autonomous vehicles such as self-driving cars , significant road conditions can include "shadowing and lighting changes, road surface texture changes, and road markings consisting of circular reflectors, dashed lines, and solid lines". Various government agencies and private entities, including local news services, track and report on road conditions to

7120-399: The road construction area may be marked for retention. These protected trees should not have the topsoil within the area of the tree's drip line removed and the area should be kept clear of construction material and equipment. Compensation or replacement may be required if a protected tree is damaged. Much of the vegetation may be mulched and put aside for use during reinstatement. The topsoil

7209-512: The road construction site. Approval from local authorities may be required to draw water or for working (crushing and screening) of materials for construction needs. The topsoil and vegetation is removed from the borrow pit and stockpiled for subsequent rehabilitation of the extraction area. Side slopes in the excavation area not steeper than one vertical to two horizontal for safety reasons. Old road surfaces, fences, and buildings may need to be removed before construction can begin. Trees in

7298-473: The road, although they can be embedded in short, shallow trenches carved in the roadway, as is done in the mountainous regions of California. For major roads risk can be reduced by providing limited access from properties and local roads, grade separated junctions and median dividers between opposite-direction traffic to reduce the likelihood of head-on collisions. The placement of energy attenuation devices (e.g. guardrails, wide grassy areas, sand barrels)

7387-404: The roads of a particular locality, including the quality of the pavement surface , potholes , road markings, and weather . It has been reported that "[p]roblems of transportation participants and road conditions are the main factors that lead to road traffic accidents". It has further been specifically noted that "weather conditions and road conditions are interlinked as weather conditions affect

7476-406: The section is deemed to comply. Geosynthetics such as geotextiles , geogrids , and geocells are frequently used in the various pavement layers to improve road quality. These materials and methods are used in low-traffic private roadways as well as public roads and highways. Geosynthetics perform four main functions in roads: separation, reinforcement, filtration, and drainage; which increase

7565-437: The slab. The grout can fill small voids beneath the slab and/or sub-base. The grout also displaces free water and helps keep water from saturating and weakening support under the joints and slab edge after stabilization is complete. The three steps for this method after finding the voids are locating and drilling holes, grout injection and post-testing the stabilized slabs. Slab stabilization does not correct depressions, increase

7654-505: The smaller draglines are now rarely used other than on river and gravel pit works. The small machines were of a mechanical drive with clutches. Firms such as Ruston and Bucyrus made models such as the RB10 which were popular for small building works and drainage work. Several of these can still be seen in the English Fens of Cambridgeshire , Lincolnshire and parts of Norfolk . Ruston's are

7743-476: The steer axle and 36,000 pounds (16.329 t) on both of the tandem axle groups is expected to do 7,800 times more damage than a passenger vehicle with 2,000 pounds (0.907 t) on each axle. Potholes on roads are caused by rain damage and vehicle braking or related construction work. Pavements are designed for an expected service life or design life . In some parts of the United Kingdom the standard design life

7832-640: Was established as P&H Mining in 1884 by Alonzo Pawling and Henry Harnischfeger . In 1914, P&H introduced the world's first gasoline engine powered dragline. In 1988, Page was acquired by Harnischfeger which makes the P&;H line of shovels , draglines, and cranes . P&H's largest dragline is the 9030C with a 160-yard bucket and up to a 425-foot boom. In 1907, Monighan's Machine Works of Chicago became interested in manufacturing draglines when local contractor John W. Page placed an order for hoisting machinery to install one. In 1908, Monighan changed its name to

7921-466: Was introduced in 1911 as the first crawler mounted dragline. In 1912 Bucyrus helped pioneer the use of electricity as a power source for large stripping shovels and draglines used in mining. An Italian company, Fiorentini , produced dragline excavators from 1919 licensed by Bucyrus. After the merger with Monighan in 1946, Bucyrus began producing much larger machines using the Monighan walking mechanism such as

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