|
||||||||||||||||||||||||||
|
||||||||||||||||||||||||||
Method
Historically, horizontal angles were measured using a compass, which would provide a magnetic bearing, from which deflections could be measured. This type of instrument was later improved upon, through more carefully scribed discs providing better angular resolution, as well as through mounting telescopes with reticles for more precise sighting atop the disc (see theodolite). Additionally, levels and calibrated circles allowing measurement of vertical angles were added, along with verniers for measurement down to a fraction of a degree- such as a turn-of-the-century Transit (surveying). The simplest method for measuring height is with an altimeter — basically a barometer — using air pressure as an indication of height. But for surveying more precision is needed. Toward this end, a variety of means, such as precise levels, have been developed. Levels are calibrated to provide a precise plane from which differentials in height between the instrument and the point in question can be measured, typically through the use of a vertical measuring rod. As late as the 1990's the basic tools used in planar surveying were a tape measure for determining shorter distances, a level for determine height or elevation differences, and a theodolite, set on a tripod, with which one can measure angles (horizontal and vertical), combined with triangulation. Starting from a benchmark, a position with known location and elevation, the distance and angles to the unknown point are measured. A more modern instrument is a total station, which is a theodolite with an electronic distance measurement device (EDM) and can also be used for leveling when set to the horizontal plane. Since their introduction, total stations have made the technological shift from being optical-mechanical devices to being fully electronic with an onboard computer and software. Modern top-of-the-line total stations no longer require a reflector or prism (used to return the ambient light used for distancing) to return distance measurements, are fully robotic, and can even e-mail point data to the office computer and connect to satellite positioning systems, such as a Global Positioning System (GPS). Though GPS systems have increased the speed of surveying, they are still only accurate to about 20 mm.[citation needed] As well GPS systems do not work in areas with dense tree cover. It is because of this that total stations have not completely phased out earlier instruments. Robotics allows surveyors to gather precise measurements without extra workers to look through and turn the telescope or record data. A faster way to measure (no obstacles) is with a helicopter with laser echolocation, combined with GPS to determine the height of the helicopter. To increase precision, beacons are placed on the ground (about 20 km apart). This method reaches a precision of about 5 mm.
OriginsSurveying techniques have existed throughout much of recorded history. In ancient Egypt, when the Nile River overflowed its banks and washed out farm boundaries, boundaries were re-established through the application of simple geometry. The nearly perfect squareness and north-south orientation of the Great Pyramid of Giza, built c. 2700 BC, affirm the Egyptians' command of surveying.
A cadastre loses its value if register and maps are not constantly updated. Large-scale surveys are a necessary pre-requisite to map-making. In the late 1780s, a team from the Ordnance Survey of Great Britain, originally under General William Roy began the Principal Triangulation of Britain using the specially built Ramsden theodolite. Types of Surveys & Applicability
Surveying as a careerThe basic principles of surveying have changed little over the ages, but the tools used by surveyors have evolved tremendously. Engineering, especially civil engineering, depends heavily on surveyors. Whenever there are roads, dams, retaining walls, bridges or residential areas to be built, surveyors are involved. They determine the boundaries of private property and the boundaries of various lines of political divisions. They also provide advice and data for geographical information systems (GIS), computer databases that contain data on land features and boundaries. Surveyors must have a thorough knowledge of algebra, basic calculus, geometry, and trigonometry. They must also know the laws that deal with surveys, property, and contracts. In addition, they must be able to use delicate instruments with accuracy and precision. On the subject of accuracy, a surveyor is typically held to an accuracy standard of twelve-onethousandths (.012) (12/1000) of an inch over a length of one hundred (100) feet. This means, for perspective purposes, that a professional land surveyor can be expected to complete a survey of a one hundered (100) foot circle and upon returning to the point of beginning not deviate from his or her course no more than the width of a human finger-nail. In most states of the U.S., surveying is recognized as a distinct profession apart from engineering. Licensing requirements vary by state, however these requirements generally all have a component of education, experience and examinations. In the past, experience gained through an apprenticeship, together with passing a series of state-administered examinations, was required to attain licensure. Nowadays, many states require a Bachelor of Science in Surveying, or a Bachelor of Science in Civil Engineering with additional coursework in surveying, in addition to experience and examination requirements. Typically the process for registration follows two phases. First, upon graduation, the candidate may be eligible to sit for the Fundamentals of Land Surveying exam, to be certified upon passing and meeting all other requirements as a Surveyor In Training (SIT). Upon being certified as an SIT, the candidate then needs to gain additional experience until he or she becomes eligible for the second phase, which typically consists of the Principles and Practice of Land Surveying exam along with a state-specific examination. Registered surveyors usually denote themselves with the letters P.S. (professional surveyor), L.S. (land surveyor), or P.L.S. (professional land surveyor), or P.S.M. (professional surveyor and mapper) following their names, depending upon the dictates of their particular state of registration. In Canada Land Surveyors are registered to work in their respective province. The designation for a Land Surveyor breaks down by province but follows the rule whereby the first letter indicates the province followed by L.S. There is also a designation as a C.L.S. or Canada Lands Surveyor who has the authority to work on Indian Reserves and National Parks. Typically a licensed land surveyor is required to seal all plans, the format of which is dictated by their state jurisdiction, which shows their name and registration number. In many states, land surveyors are also required to place caps bearing their registration number on property corners that they have set. Building SurveyingBuilding Surveying emerged in the 1970's as a profession in the United Kingdom by a group of technically minded General Practice Surveyors.[1] Building Surveying is a recognized profession within Britain but not widely recognized overseas although there is growth of the profession within Australia. The Services that Building Surveyors undertake are broad but include:
Building Surveyors also advise on many aspects of construction including:
Clients of a building surveyor can be the public sector, Local Authorities, Government Departments as well as private sector organisations and work closely with architects, planners, homeowners and tenants groups. Building Surveyors may also be called to act as an expert witness. Building surveyors must undertake an accredited degree qualification and undertake professional training for a period of at least two years, at the end of which sit an assessment of professional competance. Professional organisations for building surveyors include CIOB and RICS. Quantity SurveyingQuantity Surveyors play a key role in the organisation and financial management of construction projects. In essence they manage projects to ensure that they are built on time and to budget. Their job is to manage costs effectively and to ensure that they get the best value from contractors and suppliers. This involves obtaining tenders, arranging contracts and managing costs for the client while the works are undertaken. It is also their job to negotiate with the client's representative on payments and the final settlement. Quantity Surveyors deal with other professionals within their company as well as clients out-with the organisation. It is an extremely diverse area and can include project management, facility management, construction management and management consultancy. Land surveyorA land surveyor is an individual normally licensed by a State or in several States in the USA to perform the establishment or re-establishment of Land Boundaries in regards to ownership or rights in real property (land, water, mineral, easements and rights-of-way, etc.). The act of Land Surveying varies upon the requirements of the survey. In order to perform any type of a survey, the first step is always the research of the records involving the project, record title (deeds), existing easements, record survey monumentation and control (horizontal & vertical) and any available documentation from various public and private records that provide relevant data to the completion of the project. The next step in the process would ordinarily be the “field survey”, the process in which the Land Surveyor conducts a field examination of the site and gathers data generally by means of survey equipment such as a total station theodilite (loosely referred to as a transit) and a data collector (electronic data recorder), and / or GPS equipment (Global Positioning Satellites). In this process the Surveyor acquires a position on previously established survey monuments for vertical reference or for horizontal control or both. This is generally acquired in the form of coordinates (number values) such as a Northing and an Easting with X= Easting, Y= Northing, expressed as 0, 0 as the point of origin. In general terms the lower left of the project will be smaller numbers and will increase in value as the positions move to the North and to the East, beginning in the lower left of a project at 0,0 then if the next point is 300 feet to the East of this point and 200 feet to the North of this point the coordinate value is 300,200 (X=300, Y=200). The gathering of this data by RTK GPS is a direct coordinate value, by a total station theodilite requires an orientation into the system by setting up on a known point and sighting on a known point and then recording the angle between that line and the next point sighted at and then the distance to that point. The coordinate is then computed and recorded in the data collector, before data collectors the information was hand written in a “field book” and computations were performed later. After the fieldwork is gathered the next step is the analysis of the data and in a boundary survey, the completion of the fieldwork is performed by setting the permanent survey markers that control the boundary corners, then a survey plat and description (one or the other or both-depending on local and state requirements) is created and the final report is sent to be recorded (if required by law) in the appropriate government office, and a final copy is presented to the client. See alsoFamous surveyors
|
Sites |
Searched sites for "Surveying" |
|
No sites found. |
Sorry, no matching site records were found. |
Want your site listed here?
|
||||||||||||||||||||
|
Submit
your site |
|
Relevant quality search results and fast easy navigation throughout the
different sections of the site, make Americola.com |