Stellenbosch University is a public university situated in Stellenbosch, South Africa. It is recognised as one of the top universities in South Africa. It offers high-quality postgraduate management education focused on the development of business leadership. University Website International Location. They offer undergraduate, graduate, and executive education programmes in a variety of specializations.
ITBA has academic connections with over private companies and public institutions and also with over 50 universities worldwide, including ESCP Europe. It ranks as one of the top universities in Argentina. Its Max Von Buch Library is one of the biggest private libraries in the country. It runs administration courses at graduate and specialized levels, as well as a wide-ranging research programme and technical consultancy service for government businesses and entities.
EBAPE promotes many research projects. It fosters cooperation between institutions and exchange programs. Insper is a leading Brazilian School of Business and Economics with the primary mission of generating and disseminating knowledge in these fields. Education activities at Insper prioritize educational experiences aligning real-world demands with solid academic contents and sophisticated teaching methodologies.
Insper holds prominent national and international accreditations, and is consistently ranked as one of the best business schools in Latin America. The campus is located in Vila Olimpia, the new business center of Sao Paulo. With Founded in , USP is a public state institution and has campi placed in eight cities spread throughout the state of Sao Paulo. With education and research activities in all academic fields, USP offers undergraduate programs, graduate programs, and extracurricular programs.
The university holds a strong commitment to achieving excellence in terms of its personnel and of generation of knowledge. Furthermore, USP is an institution that is evolving rapidly in its intent towards greater internationalization. It has campuses in Vancouver, Burnaby and Surrey. Undergraduate and graduate programs operate on a year-round, tri-semester schedule.
Queen's University is a co-educational, non-sectarian, public university located in Kingston, Ontario, Canada. In national and international rankings, it has consistently maintained its status as one of the top universities in Canada. Its first commerce program was established in , making the Queen's School of Business one of the oldest business schools in Canada. The professors publish regularly in top-tier international journals in their areas of specialization. The University of Ottawa is a bilingual English and French , researched-based, international university located in Ottawa, Ontario.
Founded in , it is also one of the oldest universities in Canada. Founded in , it is also one of Chile's oldest universities and one of the most recognized educational institutions in Latin America. Composed of 4 urban campuses located in Santiago, PUC has 16 faculties, which have established a leading place in research and doctoral programs. The Universidad de Chile was founded in and is the oldest and largest university in Chile.
Located in Santiago, this public university is made up of 14 faculties and 5 campuses. Almost all Chilean presidents have graduated from the Universidad de Chile and it remains one of the most prestigious universities in South America. The Universidad de Chile enrolls approximately 23, undergraduate students and 5, graduate students.
They have over collaborative agreements with approximately higher education institutions and international organizations worldwide, including ESCP Europe. University homepage School of Management homepage. The Universidad de los Andes' School of Management is a leading business school in the capital city of Colombia. Founded in , the School of Management has been committed to training people to create, analyze, transform, and develop private, public, and non-profit organizations in Colombia and abroad.
This rating is due to a number of features that make it unique. D professor. These prestigious accreditations attest to the value of an INCAE education and are important for graduates when they enter the job market. University Homepage School Homepage. Based in Monterrey, Mexico, the Institute has 33 campuses in 25 cities throughout the country as well as a host of associated venues. It is considered to be one of the best business schools in Mexico and Latin America. UP is regarded as one of the most prestigious higher education institution in Peru and Latin America in the areas of economics, finance, accounting, and business administration.
AU has a long history of partnership with the Washington, D. Congress in Students at the Kogod School of business come from over 75 countries and one-third of the faculty come from outside the United States. Babson College, located in Wellesley, Massachusetts, is a private college recognized internationally for its entrepreneurial leadership in a changing global environment.
They offer an undergraduate program that combines applied business courses with a liberal arts education as well as graduate programmes at the F. Olin Graduate School of Business and executive education courses. They are accredited by AACSB and EQUIS and their global research projects are used as benchmarking indicators by distinguished organisations at the regional, national, and international level. Founded in , Boston College is a private university located in the village of Chestnut Hill, Massachusetts, just six miles from downtown Boston.
Boston College has approximately 9, undergraduate students and 5, graduate students. The Carroll School of Management consists of seven academic departments and six research centers. Their undergraduate program was recently ranked 16th in the United States by BusinessWeek, citing strong networking opportunities with alumni as an important factor.
Established in , ILR was the world's first school for college-level study in industrial and labor relations. The ILR School has more full-time faculty involved in teaching and research that spans a broad range of work and employment disciplines, than any other educational institution of its kind. MIT Sloan is devoted to its mission: to develop principled, innovative leaders who improve the world and to generate ideas that advance management practice.
Founded in , the university has one of the largest single-campus enrollment in the nation. The McCombs School of Business at UT Austin is consistently ranked as one of the top business schools in the nation and a top-ranked research institution. It is the oldest public business school in Texas. It is the oldest and largest campus in the University of Illinois System. The university comprises 17 colleges. The campus holds buildings on 1, acres in the twin cities of Champaign and Urbana.
Renowned as one of the premier universities in the world, Urbana-Champaign alumni include 16 Pulitzer Prize and 9 Nobel Prize winners. It has highly-ranked programmes in accountancy, business, and finance. A distinguished faculty provides instruction and academic leadership in the teaching, research, and outreach programmes of the college. The Carlson School of Management has a commitment to imagination, engagement, and ambition. Based in the Twin Cities of Minneapolis and St. Paul, housed in the University of Minnesota, the Carlson School is a leader in business education and research.
Their approach connects students to unique experiential learning opportunities, dynamic international education programs, and to a vibrant network of businesses throughout the state and beyond. Their programs are consistently ranked highly both nationally and internationally.
The Carlson community includes more than 5, current students and an alumni network of more than 50, graduates worldwide. The Moore School of Business of the University of South Carolina was founded in and is best known for its outstanding leadership in international business education and research. The school is home to several leading journals including the Economics of Education Review. The school conducts an annual 'Economic Outlook Conference' that draws widely from the public sector as well as academia.
Ranked as one of the country's top schools for accounting, finance, entrepreneurship and international business studies, Marshall also shares the rich history and vibrant community of the USC academic system. Marshall is the first school to require international travel and study projects as part of every MBA degree. The university has three campuses, with its largest campus in Seattle's University District and 2 other campuses in Tacoma and Bothell.
The Michael G. It is one of only a few U. It consistently ranks among the top business schools in the United States. It is organized into 20 schools. It is recognized for a unique specialized MBA approach that produces business leaders. More than 30 business-based student organizations offer students the chance to learn about business and network with professionals. Washington University in St. Louis is a private university located in St.
Louis, Missouri and was founded in It has recently been ranked 30th in the world by the Academic Ranking of World Universities and has faculty and students from over countries. The Olin Business School offers bachelor, master, and doctorate programs and has been ranked among the top business schools in the world by the Financial Times and the Wall Street Journal.
Since its establishment in , it has been amongst Australia's leading universities. It has produced 5 Nobel laureates, Rhodes scholars international postgraduate awardees for study at the University of Oxford and is a member of the Group of Eight, as well as the Sandstone universities. Its main campus is located on the cultural boulevard of North Terrace in the Adelaide city centre. The university also has 4 other campuses throughout the state, and a campus in Singapore. The exchange program takes place at the Faculty of the Professions located in Adelaide, which encompasses 5 separate schools, covering a diverse range of disciplines and has a remarkably equipped Postgraduate Student Resource Center.
Founded in , they are a leading provider of management education in the Asia Pacific region. The Indian Institutes of Management IIMs are the top Business Schools in India and also conduct research and provide consultancy services in the field of management, including non-corporate and under-managed sectors.
This image had found root in Mexico with the appearance of an apparition of the Virgin Mary to Juan Diego, an Aztec, in , at the shrine of Tonantzin, the Aztec mother goddess. Following the apparition's directive, Juan Diego attempted to convince the local Catholic authorizes of the miraculous occurrence. Upon his failure here, he followed her orders to present to the authorities roses wrapped within a blue cape. It was in January and roses had never been at the shrine at that time of year.
However, there they were and Juan Diego did as the apparition demanded. Upon presenting them however, instead of roses in the cape there was an image of the virgin. Thus was born what would become overtime the Patroness of the Americas , and the fundamental national symbol of Mexico. Even with this strong Catholic heritage behind him, Don Bernardo yet recruited an army of citizens from the United States, a nation with Anglo-Protestant roots. Not only were those roots Protestant, but they were riding the crest of a Second "Great Religious Awakening.
Together, the assemblage worked its way from Louisiana to San Antonio, winning every major battle en route. Only when this change in their government brought a realignment of their politics and army, isolating the units according to race, did the Army of the 1st Republic lose a major battle. Awesome was that loss; the Battle of Medina on 18 August marked the most disastrous defeat ever on Texas soil.
As implied on the marker cited above, after the battle Spanish troops under the command of Colonel Ignacio Elizondo pursued the remnants of the escaping Texas Army. Establishing his headquarters between the area of present Madisonville and the Trinity, Elizondo directed his forces to execute with impunity most of the Texas Patriots they managed to apprehend. In the process, they also demolished the very town of Trinidad to the extent that its exact location is yet a matter of dispute. The great lesson of the First Republic of Texas, torn as it was by disastrous dissension at the Battle of Medina, is "united we stand, divided we fall.
Besides its association with the area where Texas was first declared a free republic, the Madisonville area is fascinating for other reasons. For example, a Madison County man, Major W. Young, is credited with originating the battle cry, "Remember the Alamo! Madisonville is a real Texan's cattle town. In the 's and 60's, Madison County boasted more cattle per acre than other county in Texas.
The famous Sidewalk Cattleman's Association event, celebrated in late May and early June, proffered the idea that Madisonville had too many "sidewalk cowboys. Specifically, so the legend goes, should one have at least one cow, one was allowed to wear one pants leg tucked inside a boot. It took the ownership of at least two or more cows to warrant having both pants legs tucked in.
Another major event of the year is the famous Mushroom Festival , complete with a dinner the evening before a full Saturday of fun and games and, of course, delicious culinary treats. The festival is in late October. Between Madisonville and the Trinity outside of Midway is another marker to an event with impact on the area of the Cradle Road. This is the story of a settlement called Bucareli. As a consequence, many settlers from East Texas were forced to move west to the new seat of government.
Some of those removed became unhappy with their new surroundings and appealed to the Spanish Viceroy Antonio Maria de Bucareli to allow them to move closer to the area of their original homes. The appeal being successful, they established a community at the junction of San Antonio Road and the Trinity River. Cleaning spoil out of the pipe during an intermediate stage of construction can be done manually or by the use of a scraper winch system.
There is limited information in state highway agencies specifications about soil compaction methods. Yet most are concerned about the effect of dynamic action on the surrounding utilities, pavements, and structures. Research is on-going to predict movement due to impact moling under various soil conditions. This should help gain wider acceptance of this soil compaction method in roadway crossings. Particular concerns by state are listed below:.
Typically, there is no bidding on individual impact moling jobs because municipal agencies have their own crews with equipment or they hire contractors.
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Instead, guidelines are needed on how to purchase the impact mole and not how to proceed with individual impact moling projects. Pipe bursting is a method of on-line replacement consisting of a bursting tool that moves through the existing pipeline, applying radial forces to break open or to split the pipe.
A spreader device on the bursting tool pushes the fragments of the pipe into the surrounding soil. A thin-walled sleeve is generally pulled into the newly formed bore directly behind the spreader. This sleeve, made of either push-fit PVC pipe or butt-fused polyethylene, protects the product pipe from contamination by small quantities of lubricating oil present in the exhaust gases from the burster head.
The sleeve also prevents the product pipe from being damaged by fragments of the old pipe in the surrounding ground. On-line replacement involves the replacement of existing pipes size-for-size or up-sizing with new pipes in the same location economically and with minimal or no excavation. An ideal candidate for on-line replacement is a pipeline with inadequate capacity or whose structural condition is too poor for relining.
Additional developments continue to extend the capabilities of on-line replacement systems, and add to their economic benefits. Typically, existing pressure or gravity pipes are replaced or up-sized in this fashion. There are a wide range of on-line techniques available. Most of them differ in the way that the old pipe is fractured and the new pipe is replaced. Most are designed to replace brittle pipes, but some are designed for ductile materials like steel.
Pipe bursting is the most common trenchless method for on-line replacement. Figure 18 shows a standard pipe bursting head. Other techniques that will be discussed briefly in this section include:. The pipe bursting technique was originated in the United Kingdom and in the United States in the early s.
In some countries, it is referred to as pipe cracking. It was originally designed to replace old cast-iron gas mains. With its widespread use as a technique to replace small diameter cast-iron potable water systems, pipe bursting has an increasing worldwide market. Pipe bursting involves the insertion of a cone shaped tool, or head, into an old pipe in the insertion pit, as shown in figure It fractures the old pipe and forces the fragments into the surrounding soil.
The new pipe is pushed in or pulled in behind the bursting head. The rear of the bursting head is connected to the new pipe and the front end is connected to a cable or pulling rod in the reception pit. To cause the fracturing of the old pipe, the base of the bursting head is larger than the diameter of the old pipe. Its outer diameter is slightly larger than the diameter of the new pipe. This provides space for maneuvering the bursting head in the pipe and also reduces friction on the new pipe. For this technique, air driven impact moles, also called ground piercing or earth piercing tools as described in the section on impact moling and ramming, are driven forward by a hammer that repeatedly strikes an anvil at the nose of the tool.
The mole, with fins, travels up the existing pipe, breaks it out and forces the fragments into the surrounding soil. The percussive fracture mechanism breaks up the existing pipe with its high impact force. This technology is used for brittle materials like cast iron, spun iron, clayware and unreinforced pipe. This is the most popular technique for size-for-size replacement and up-sizing of pressure pipes.
An improvement to this system came in the form of a hydraulically powered rod system to pull the burster through the pipeline. This new method offers increased power control and greater safety to operators and the facility for increased pulling power and larger diameter pipes. The new pipe that is installed is usually polyethylene, pre-welded to the required length. It may be necessary to have intermediate jacking, rather than to have to rely on the pull from the bursting head at the front, or on the jacking force from the rear.
Pipe bursting allows the pipe capacity to be maintained or increased. Therefore the progress rates are much greater when compared to open cut, with less surface disruption. Since the percussion of pneumatic pipe bursting can be felt on adjacent pipes, services, building foundations and paved surfaces, an alternative, hydraulic pipe bursting, may be used in sensitive areas. This bursting head has petals that open and close under hydraulic pressure. When the hydraulic pipe bursting head is used, it first expands to crack the old pipe, and is then retracted.
The new pipe is jacked into place and the burster is pulled ahead. This process is repeated, and more pipes are added to the end as work progresses. The hydraulic burster is designed to operate with short lengths of product pipes and is primarily for sewerage and gravity pipeline applications, rather than for pressure pipes.
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Pipelines 1 m 3. There is also a portable system that can replace pipes up to mm 5. Another variation is to use a powerful hydraulic pushing and pulling machine that acts on high tensile steel rods connected to the bursting head that is pulled through the existing pipeline. The new pipeline is then drawn or jacked behind the head. The typical pulling capacity is to kN 20 to tons. This method relies more on the power of the pulling machine than on the hydraulic expansion of the head. New pipes used with the hydraulic pipe bursting method are commonly polyethylene that have joints that snap together.
Replacement clayware pipes have also been introduced that allow sewers to be replaced or upsized. Clayware pipes have stainless steel collars to enhance the shear strength at the joints. They can withstand higher jacking forces than most polymeric materials, but they are heavier and may require powered systems for lifting and handling on site. When using pipe implosion, the pipe fractures inwards prior to the outward displacement of pipe fragments. The procedure is similar to that of pipe bursting.
The hydraulic rodding system consists of a static bursting head, fitted with fins, that is pulled through the pipeline by a series of rods. These rods are first pushed through the pipeline by a hydraulically powered rig that is located in the lead trench.
The steel rods, approximately 1 m 3. After each rod has been inserted, a new rod is threaded onto the previous rod and the process is repeated. At the far end of the pipeline, the bursting head is attached to the rods. As the rods are pulled back, the old pipe is broken open. Pipe eating is a variation of microtunneling. The old pipe is consumed by the tunneling machine as the new pipe is jacked into place.
It crushes the existing pipe with an eccentric-cone crusher. This allows realignment and upsizing of the sewer. These systems can also allow on-line pipe replacement without flow diversion. This pipe eating process can be used for the replacement of clayware, concrete, asbestos cement, and reinforced concrete pipes. This system has teeth in the crusher cone that can cut the reinforcement in a concrete pipe, allowing excavation of all conventional pipe materials in addition to the concrete. This technique is suited for large diameter pipes and in situations where the heave caused by expansive upsizing could damage the surface or adjacent services.
Pipe reaming with a horizontal directional drilling machine is a newly introduced technique. A specialized reaming tool grinds up the old pipe as the new one is drawn in behind. The fragments are suspended in drilling fluid and pass through the existing pipe to a manhole or recovery pit.
This system was developed specifically for the replacement of steel pipes. This technique works in a similar manner to rodding techniques, but a splitting head is used to break open the pipe. This head consists of a series of discs that score the inside of the pipe. Blades follow that cut open the pipe. The spreader behind the blade pushes the sections of the pipe open, to allow the replacement pipe to be installed. If the pipes that are to be replaced are non-brittle, the burster may cease to make forward progress.
An alternative approach was developed that uses a cutting and an expanding head that can cut through the wall of a ductile pipe or fitting. This head is pulled through the old pipe by a hydraulic rod system and slices open the old pipe as the new pipe is drawn in behind. It can be used on pipes made of steel, ductile iron, repaired cast iron, asbestos-cement, PVC and polyethylene. Diameters of up to mm 12 in have been installed under suitable conditions. In pipe ejection, the old pipe is jacked towards the receiving pit where it is broken and removed, while the new pipe is simultaneously inserted.
This is commonly used with old lead pipes. Lead pipes are a significant health risk when the lead is absorbed into the drinking water. The existing lead pipe is pulled out of the ground and replaced with a new polyethylene pipe. For this technique, a steel cable is inserted into the lead pipe, which expands and grips the walls of the lead pipe.
The old pipe is extracted and wound onto a drum. The new replacement polyethylene pipe is pulled in at the same time by the cable. This technique is fairly successful for straight service pipes, but excavation may be required if the pipe has a sharp bend, is surrounded in concrete or has been fitted with flange couplings.
For pipe bursting applications to be successful, the pipes should be made of brittle materials like vitrified clay, cast iron, plain concrete, asbestos and some plastics. Reinforced concrete pipe can also be replaced if it is not heavily reinforced or if it has not deteriorated substantially. For ductile pipes steel or ductile iron they can be replaced only by pipe splitting. Specially designed heads can reduce the effects of existing sags or misalignment of the new pipe.
The size of the pipe that is typically replaced can range from 51 to mm 2 to 36 in in diameter. The size of the bursting head is increasing over time, and pipes with diameters up to mm 48 in have been replaced. See the previous section for more detailed information on pipe bursting equipment.
The primary applications of pipe bursting are in gas and water main renewal. It is also becoming more prevalent among trenchless technologies for the replacement of old and undersized sewers. Significant increases in pipe size can be accomplished, as noted in a replacement of an old concrete sewer, about mm 15 in in diameter, which was upgraded to a mm 24 in plastic main.
Typically, pipes that are burst have diameters between to mm, 6 to 15 in and have been replaced with pipes to mm 32 to 36 in in diameter. The success of the operation depends on having accurate information about the original construction materials and the condition of the existing pipeline. For example, if there have been localized repairs or if the pipeline is encased with concrete, problems could arise during construction that may not have been identified during the planning stages. Typical lengths for pipe bursting drives are 91 to m to ft lengths, which is also the typical length between sewer manholes.
However, longer drives have been replaced. Pipe bursting is currently being used in California and Texas for water and sewer pipe replacement. See reference 28 and Appendix C. These specifications cover materials, preparation, construction methods, pipe joining, payment and warranties. General guidelines and sample technical specifications for the reconstruction of sanitary sewers by the pipe bursting process are also available. Notable design considerations are the ground and groundwater conditions, surrounding subsurface utilities, and the effect of pipe bursting on nearby structures.
However, the pipe bursting process is currently not covered by ASTM specifications, although the plastic replacement pipes are covered. The previous section provided a basic overview of several different trenchless technology applications.
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Throughout the section, information regarding the appropriate use of each technique was given. This section provides a summary of information on all the methods described in the previous section. This section includes the following discussions:. These sections are intended to provide addition information to help agencies and private industry determine the most appropriate method of trenchless technology, or if trenching is indeed the most appropriate method of utility construction. This is not a complete catalog of methods and applications, and the reader should consult references in the bibliography and a trenchless technology contractor for a detailed analysis of a particular situation.
This section provides information on the various trenchless methods and their applicability to the individual types of utilities and types of construction. The tables contained in this section include not only the methods of trenchless technology described in section 4. The four major types of construction include:. The trenchless technology methods most suited for the combination of construction and utility type are shown in the following four tables, which are organized by construction type: new installation table 14 , online replacement table 15 , renovation table 16 , and repair and maintenance table This information is summarized from reference The selection of a trenchless method depends not only on the type of construction and type of utility, but on local attitudes, policies, and regulations.
For example, the City of Dallas, Texas, banned directional boring in the downtown area after a contractor hit a water main on Labor Day, Other restrictions on the choice of construction method could also include, among others, ground conditions, availability of trenchless technology contractors and equipment, cost, safety, and the technical feasibility of the various method desired. The appropriate techniques in the preceding tables are only recommendations, and should not be taken as absolute. There will certainly be exceptions to the recommendations in these tables, as various highway agencies, cities, and industry users become more familiar with the technology and its capabilities.
Standard pipe sizes, bore lengths, and depths are also a consideration in determining the appropriate method. As described above, the range of application guidelines in the previous table should be used as a general guide in determining an appropriate method for trenchless construction. As technology improves within the various methods, each may expand its range of depth, length, and diameter application.
This section summarizes the advantages and limitations of the various trenchless technology applications. In general, all trenchless technology applications have the common advantage of reducing the impact to the surface, and to pavement structures. Although some city ordinances consider directional drilling or microtunneling to be a disruption to the pavement structure, the surface of the pavement is generally not impacted.
Other benefits include reduced impacts to traffic, and the other costs or impacts associated with traffic congestion. Although this section includes some reference to cost and safety, they are only made as they relate to the advantages and limitations of the particular method. These will be discussed in more detail in later sections. In general, the advantages of HDD are similar to those of the entire trenchless technology industry. HDD allows for rapid installation, and relatively large pipelines can be installed over long distances. The guided bore can be made accurately, and safety is greatly improved when used in conjunction with subsurface utility engineering.
Line and level available is controllable, which can also be confirmed by a print out.
Mini-HDD equipment is portable, self-contained, and is designed to work in small, congested areas. Limitations on HDD include the amount of space required to develop the underground access points. A relatively large area may be required for the drilling rig and associated equipment at the drill entry point.
Another large area is generally required at the drill exit point, although surface-entry operations can reduce the need for access shafts. Other limitations include the possibility that the bore may collapse in some granular soils and gravels. Ground movement must be considered, especially in midi- and maxi-HDD applications. The pressure and high flow rates of the drilling fluid can cause some excess soil to erode, which leaves a void outside the installed pipe, which may eventually collapse.
Additionally, pressure may cause the drilling fluid to flow into a soil stratum as the drilling head advances, potentially causing heaving of that soil layer. Drilling fluid can also seep to the surface in shallow cover. Other limitations include excessive torque and thrust applied to the drill stem, especially in curving boreholes, which can cause drill stem failure in mini-HDD application.
Both auger and slurry boring have decreased risk of disrupting the surface either by subsidence or heaving, but an experienced operator is necessary to minimize the risk. Auger boring can be used in a wide range of soil conditions. Table 5 on page 19 of reference 17 provides extensive information on the influence of ground conditions on auger boring operations. Both auger and slurry boring can be used to install any type of pipe or cable.
Both auger and slurry boring are generally un-steerable, however some basic steering systems are available.
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Both also require entry and reception shafts. As with any trenchless technology application, a thorough site investigation is recommended, primarily to identify obstacles such as large boulders and soft ground. Auger boring can accommodate larger rocks, up to one-third the diameter of the casing.
In auger boring, the casing should be made of steel, to accommodate the steel augers turning inside the casing. Subsidence is possible with overexcavation in slurry boring, but is less of a risk in auger boring. There is a greater risk of heaving, however, in auger boring if excessive force is applied at the excavation face. If used properly, both pipe jacking and microtunneling can have a low risk of surface disruption. Subsidence can be kept to about 25 mm 1 in.
Pipe jacking has been in use for over years, thus providing a long history of success and much experience in the industry. As with most trenchless applications, pipe jacking and microtunneling require a skilled operator who can make adjustments based on almost imperceptible changes in the operation of the machines. Again, a thorough site investigation is essential to the success of the project.
Access shafts are required at both ends of the drive. Soil characteristics can have a significant effect on the choice and application of pipe jacking systems, including the bore face excavation, which must be properly supported to prevent sudden collapse. Since the definition of pipe jacking compared to microtunneling is that workers are present in the jacked pipe, the safety of the operators is important.
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Pipe jacking systems require pipes that can transmit the jacking forces expected in the operation. Impact moling and pipe ramming operations are generally much more simple to operate than other trenchless applications. Due in part to the simplicity of the methods, these types are generally less expensive than other operations as well. Pipe ramming allows larger casings to be installed in a wide range of soil conditions.
Most state highway agencies to not consider pipe ramming in their specifications explicitly, but experience has found that many do not oppose the method. Operations in hard soils can be difficult, including the risk of deflecting the impact mole or lead pipe off course due to large rocks, changing soil characteristics, or other obstructions. Impact moles and rammed pipes have little to no steering control, and are used primarily for straight-line bores.
Both types present the risk of damaging existing utilities, as do other methods of trenchless technology. Closed-face pipe ramming operations should be at a depth at least 10 times the diameter of the installed pipe. Advantages of pipe bursting for in-line pipe replacement include the fact that the alignment of the pipe is already established. This type of operation also provides the flexibility of maintaining or increasing the pipe capacity. Compared to open trench operations, the progress of pipe bursting can be much greater.
Also, compared to other trenchless operations, there is less vibration, so damage or other impact to nearby services and structures is minimized. A limitation of this type of operation is that with the bursting of the pipe, and its expansion radially outward, existing utilities can be damaged, if they are not well-defined and located prior to commencing construction. Surface displacement can be extensive, especially in shallow applications, or in less compactable soils. Also, where unexpected conditions are encountered, such as unrecorded repair collars or adverse soil conditions, the operation may need to be stopped and excavation may be required to get past the obstruction.
Another condition that generally requires additional excavation is negotiating sharp bends in the existing pipe. Additionally, excavations must be made to connect the new pipe to the existing service. Although trenchless technology methods of utility installation and maintenance generally impact the public and surrounding infrastructure to a lesser magnitude than utility cuts, there are some potential impacts that should be understood. Many of the trenchless methods described in this manual have similar potential impacts, while others have unique impacts that may affect the public or property.
The following is a list of some of the potential impacts that should be considered when deciding on trenchless technology for a project:. Loose, cohesionless, and granular soils are more susceptible to bore hole collapse if a casing is not placed immediately after excavation. Pipe jacking, and auger and slurry boring are most affected by this type of soil with respect to collapse or subsidence. Pipe bursting can cause outward ground displacement along the pipe alignment.
The displacement is typically localized, and their effects dissipate rapidly away from the bursting operation. Some causes for displacement or upheaval include:. These displacements can also cause damage to nearby utilities if they are within two to three times the diameter of the new pipe. Ground vibrations can affect the surrounding soil and adjacent structures. This can be caused by pneumatic pipe bursting, as well as impact moling and pipe ramming. Other sources of information regarding the potential impacts and costs of trenchless technology can be found in reference This section discusses both the components of cost associated with the trenchless methods and the overall conditions to consider when determining the economic feasibility of the methods.
It also gives a range of cost for each method of trenchless construction. Such an economic analysis is an important step in determining the appropriate method for construction. An example of one type of economic analysis is shown in figure The range of trenching costs, however, rises rapidly based on the depth.
The information shown in this figure is reasonable, since deeper excavation for trenching methods requires much greater expenditures for labor, safety measures, and equipment. Conversely, trenchless applications do not incur much additional cost based on depth, once the equipment has entered the ground. Some additional costs could be realized in the required depth of entry and exit pits, or time and pipe required to get down to the appropriate depth. This example assumes consistent soil, ground water, and other conditions at the construction site.
As conditions change, the break-even depth may change. If the depth is consistent, a different type of economic analysis may be necessary. For a particular project, the specific costs associated with the available methods should be considered, and compared to traditional trenching methods. In addition to the costs related to construction, the indirect costs and other impacts should be considered. These were discussed in chapter 2. Although it is difficult to quantify many of the indirect costs, such impacts should be included in some manner in the economic feasibility analysis.
Many of the trenchless methods described in this manual share cost components. Some of the methods have more particular costs associated with the construction, such as boring, pipe ramming, and pipe bursting. The general costs associated with the use of trenchless technology include: Besides the general costs that are associated with most of the trenchless methods described in this manual, other costs that are specific to various methods should also be considered.
These include, but are not limited to, the following:. Each of the costs involved in a potential choice for construction should be considered in a cost analysis that compares to traditional trenching. The next section discusses the specific range of costs for many of the trenchless methods described in this manual. The cost information in this section is not necessarily current, although the relative values should be fairly consistent over time. Conditions that could change the relative nature of these costs include technological innovation within specific methods that do not cross over into other methods, and governmental regulations that impact specific methods and not others.
Other conditions that could effect a change in the relative nature of these costs are also possible. The cost information contained in this section is largely taken from Table 10, page 58 in reference It is important to maintain jobsite safety throughout any project. Special consideration must be given to trenchless projects, however, due to the level of uncertainty involved in the operation.
This section only provides an overview of the steps that should be taken to ensure safety at the jobsite. The following components are essential to have in any safety program. This information is largely from reference These components, as part of a formal, written safety program, can help promote responsibility and accountability, and the overall safety and success of the project. The most important aspect of a trenchless project is likely to be the planning stage. It is at this point in the project development that potential risks and problems can be identified and mitigated.
Contingency plans can then be made or adjusted. Alternative plans and design adjustments can be made during the planning process while impacting the project as little as possible. Poor planning can create larger problems during the project, including requiring design changes after construction begins, unexpected utility relocations, etc.
The project planning discussion contained in this section is largely a summary of reference Although this reference is directed at horizontal directional drilling, many of the planning aspects are similar among most methods of trenchless technology. The following seven categories are identified in reference To this point, chapter 4 has discussed the various trenchless technology methods, their application, advantages, limitations, and other aspects of the technology. This section is a summary of subsurface utility engineering, its advantages and limitations, and case studies additional technologies that have, and continue to improve the safety, reliability, and technical and economical feasibility of trenchless technology applications.
Some reasons SUE may not have become as widespread in the recent past could be related to the following:. Development of SUE methodologies has primarily been on the east coast. However, national standards have been under development, and should be completed in the near future.
Overall, the SUE methodologies have been successful. Of 71 projects studied by Purdue University for economic benefits, only three had a negative return on investment. The types of people involved in conducting and studying SUE include both office and field personnel, such as highway designers, utility experts, field technicians and specialists, survey crews, records researchers, CAD technicians, geologists, etc.
Subsurface utility engineering is an engineering process for accurately identifying the quality of subsurface utility information needed for project plans, and for acquiring and managing that level of information during the development of a project. By identifying the quality of the information, engineers and contractors can move ahead with design and construction work with a certain level of confidence in the existing utility data. The design and construction activities can be planned, taking into account the existing utilities, and appropriate clearance can be planned which considers the margin of error in the utility location.
This information is based on four quality levels. Each level can be thought of as representing a different degree of risk. Depending on the importance of the project and the potential cost involved in an accident, engineers may justify the expense of a higher quality level and require the utility location information to conform to that quality level.
These levels range from A through D, with Quality Level A representing the highest degree of accuracy. The following discussion of the four quality levels is a summary of a discussion in reference Quality Level D QL-D This information is obtained through utility construction records and location activities in the past. This information is very unreliable, and very little, if any, confidence should be given to the data. The contractor is generally liable for the safe negotiation of the underground space, or to locate the utilities on his own.
Data of this quality level is generally considered as an "unknown or differing site condition", thus allocating the risk to the contractor. Risk is assumed by the engineer or surveyor. QL-D information is correlated to that found by the visual inspection. Quality Level B QL-B Utility location data at this level of quality is obtained through geophysical techniques to identify the existence and horizontal location of existing utilities within a standard margin of error.
This type of information must be reproducible by similar methods, and must be recorded for later use. As the horizontal location of existing utilities is identified with a more narrow confidence margin, the liability assumed by the engineer also increases. This information is obtained by visual verification of the utility in-place using non-destructive digging equipment. This requires actual exposure of the facility so that location and size can be determined.
The liability assumed by the engineer is yet again increased, since construction documents and activities will depend greatly on the accuracy of the utility location data. Subsurface Utility Engineering has provided many benefits to a large array of agencies and entities, including highway agencies, airports, utility companies, and nuclear power plants. A list of some of the benefits cited in the literature was reported in reference These benefits, and others, have been realized by actual users of SUE. Some of these benefits and cost savings are illustrated in the case studies in the next section.
This section includes short summaries of projects that demonstrate the effectiveness of subsurface utility engineering studies. Many of these summaries are taken from references 35 and On a highway project in Maryland involving realignment of a state road and widening from 2 to 6 lanes, the use of SUE enabled the Maryland State Highway Administration to redesign the hydraulic system to minimize conflicts with utilities. Instead of relocating 5, feet each of gas, water, and sanitary sewer lines, conflicts were reduced and only about feet of each utility needed to be relocated. The data obtained showed that conflicts would have occurred at almost half of the locations.
Design changes were made prior to beginning of construction and about 80 percent of the conflicts were resolved. This project utilized three different SUE quality levels for different areas of importance. QL-B information was obtained in more critical areas to develop a plan view of the utility system around the nuclear power facility. The owner then obtained a comprehensive map of all utilities in the area, with varying degrees of reliability depending on the relative importance of each area.
In a politically sensitive area, 29 test holes were excavated to verify data previously supplied to the utility company. Of the 29 holes, six were found to be areas where the existing utility information was in error. Such errors could have cost the utility company in time, money, and embarrassment if they had not been detected. On a parking deck project, QL-D information was provided by one contractor. Some time later, another contractor provided QL-B information. An error rate of about 30 percent was found between the two sets of location data, illustrating the benefit of obtaining more accurate data.
As seen in other case studies, vacuum excavation can be relatively inexpensive. As part of the investigation, a survey was conducted among state highway agencies and some cities. The results discussed in this section relate only to those questions in the survey referring to the use of trenchless technology. A summary of the results is discussed in section 4. Another part of the investigation involved informal interviews conducted primarily by telephone to assess the attitudes of those involved in utilities in and around pavements.
Interviews were conducted with representatives from state highway agencies, telecommunications companies, water and wastewater agencies, and others. These informal interviews are summarized in section 4. The survey conducted by the research team included many questions regarding right-of-way management and policies, and one section regarding the use and experience with trenchless technologies. Representatives from 30 states and cities responded to the survey. The following subsections contain discussions of responses to the individual questions within the trenchless technology section of the survey.
Most responses to this question indicated that the experience has been "generally good". Some of the positive comments indicate the following:. The following comments were made regarding the major technical obstacles to trenchless technology:. Some of the major attitudes among the state highway agencies which can have the effect of inhibiting the use of trenchless technologies include the following. These are the opinions of the various respondents. In addition to these comments regarding attitudes inhibiting the use of trenchless technologies, six respondents suggested that there are none in their experience.
Most of the respondents suggested that through policies, incentives, disincentives, availability of information, etc. Some indicated that this was a possibility, and some had no comment. None of the respondents suggested that this could not be done. Of those indicating that pavement utility cuts can be reduced through those actions mentioned in the previous question, the following were suggested as being the most promising methods, in order of frequency. Overall, the responses to the trenchless technology section seemed to indicate that many states have had some good experiences in using or specifying trenchless technologies.
It is also evident that more information regarding potential policies, specifications, etc. During the course of the project development, several informal interviews were conducted to assess agency and industry attitudes and opinions regarding the use of trenchless technology and other methods to reduce the frequency of pavement utility cuts. This section summarizes the attitudes, usage, and innovative techniques that are used by those interviewed while conducting these telephone interviews.
The following are methods of use and innovations, on both the industry and the agency sides, which have proven successful. New technologies are constantly being developed. Many of these complement the trenchless technology industry, and others use different methods of installing or helping install facilities. This section is for informational purposes, and only presents a few typical new technologies. This section does not intend to promote or endorse any particular company or product, nor does it purport to present information on all new technologies that may be available or under development.
Some of the promising new technologies include the following:. As technological advances continue, the advantages to the trenchless and other technology industries will also improve. The reliability of trenchless technology will increase, as will the positional accuracy of the boring heads.
The probability of striking existing facilities and other objects will also decrease, as location and steering capability improve. Technologies relating to subsurface utility engineering studies will also improve the ability to locate existing facilities and map them accurately for the trenchless equipment operator.
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