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Transit-tape survey
Transit-tape survey is a kind of surveying that can produce a plan containing only the configuration of the site. Transit-tape survey consists of 1. spade-work, 2. reconnaissance of the site, 3. field work and 4. office work. Spade-work includes collecting plans and maps that carry information from the previous surveying. Reconnaissance of the site includes inspection of the site, clearing of it, comparing previous plans and maps with the site. Field work consists of making measurements of theodolite traverses which comprise a system of broken lines and of surveying the site.
Office works are subdivided into two stages:
a) calculation analyze of surveys,
b) making up plans in drawing ink with the conventional signs and according to the given scale.
In transit-tape surveying we use theodolite, rod, straight-edge, and tape-measure.
There are different types of the theodolite. Theodolite 2T-30P is a type of theodolite of double precision (accuracy). It is of the direct representation. The other ones are theodolite T-2, precision 2, T-5, precision 5.
Atheodolite consists of a limb, an alidade, slow-motion screws, a tribrach, a telescope tube and a reading engine. It has two levels: one at the horizontal circle and another on the telescope tube; slow-motion or micrometer screws, 2 thumbscrews of the alidade and the limb, a mirror and a rack and pinion gear (a mean for making representation of greater accuracy)
The theodolite has 2 positions of the circle while making surveying: a right circle and a left circle. If the vertical circle is to the left we deal with the left circle; if to the right it is the right circle. For the purpose to change the position of the circle you should move the telescope tube through the zenith and then turn it into 180 degrees.
Theodolite traverses can be closed (polygons), unclosed (which as a rule rely upon the lines of the polygons and are between the fundamental geodetic points, and suspension ones (which cannot be controlled and are seldom used).
The lines in theodolite traverses are measured with the help of a straight-edge, a tape-measure but sometimes there are obstacles of different kinds, for example ravine, streams, ponds etc. An inaccessible distance is a distance that cannot be measured with the help of a straight-edge or tape-measure. It is measured with the help of range-finder.
To measure an inaccessible distance one should launch basis-lines from 20 to 100 m and then get 2 triangles. It is necessary to measure their angles and after that to find necessary distance according to the sine theorem.
Word List
| to determine-визначати transit-tape survey-теодолітна зйомка spade-work- підготовчі роботи recognaissance - рекогносціровка field work- польові роботи office workк- камеральні роботи previous-попередній to compare-порівнювати measurements-вимірювання theodolite traverses-теодолітні ходи broken lines-ломані лінії to be subdivided into-бути поділеним на to make up plans-складати план conventional signs-умовні позначки scale-масштаб | rod- рейка straight-edge- мірна стрічка tape-measure-рулетка direct representation-пряме зображення precision (accuracy)-точність slow-motion (micrometer) screw- навідні гвинти tribrach -підставка rack and pinion gear- кремальєра reading engine- відліковий пристрій thumbscrews- закріплюючі гвинти suspension traverses- висячий хід obstacle- перешкода an inaccessible distance- недосяжна відстань to launch basis-lines- викинути базис |
Вправа 1
Підберіть терміни, подані ліворуч, до їх визначень праворуч:
| 1 to determine the size and the shape of the Earth 2 transit-tape survey 3 spade-work 4office work 5 previous results of surveying 6 to make measurements- 7 theodolite traverses- 8 broken lines- 9 to make up plans- 10 conventional signs- 11 reduced scale- 12 straight-edge- 13 direct representation- 14 double precision 15 an inaccessible distance- 16 to launch basis-lines- | aвикинути базис b пряме зображення c недосяжна відстань d ломані лінії eскладати план f теодолітна зйомка g підготовчі роботи h камеральні роботи i попередні результати зйомки k проводити вимірювання l теодолітні ходи m умовні позначки n визначати розмір та форму Землі o зменшений масштаб p мірна стрічка r подвійна точність |
Вправа 2
Закінчіть речення:
1. Transit-tape survey is a kind of surveying that ………
2. Transit-tape survey consists of ………………………
3. Office works are subdivided into ………………………
4. In transit-tape surveying we use………………………
5. The theodolite has two levels: …………………………
6. The theodolite has 2 positions of the circle: ……………
7. For the purpose to change the position of the circle you should move …………………..
Вправа 3
Відкоректуйте твердження:
1. The transit-tape survey produces a plan containing all features of the site.
2. Spade-work includes inspection of the site, clearing of it, comparing previous plans and maps with the site.
3. Theodolite 2T-30P is a type of theodolite of double representation.
4. Closed traverses rely upon the lines of the polygons and are between the fundamental geodetic points.
5. An inaccessible distance is a distance that cannot be measured with the help of the range-finder.
Вправа 4
Перекладіть речення:
1. Теодолітна зйомка – це зйомка в результаті якої отримуємо план з конфігурацією ділянки.
2. При підготовчих роботах збирають данні з попередніх зйомок.
3. При рекогносцировці ґрунту порівнюють попередні плани та карти з місцевістю.
4. Теодолітні ходи можуть бути зімкнутими, розімкнутими та висячими.
5. Недосяжна відстань - відстань, яка не може бути виміряна за допомогою мірної стрічки.
Вправа 5
Дайте відповіді на запитання:
1. What types of instruments are used in a transit-tape survey?
2. What are the main parts of the theodolite?
3. How many levels does it have?
4. What positions of the circle does the theodolite have?
5. When do we speak about the left or right circle?
6. What should be done to change the position of the circle?
Вправа 6
Підберіть пояснення до понять:
| 1Surveying is 2 Transit-tape survey is 3 Spade-work is | a making measurements of theodolite traverses which comprise a system of broken lines and of surveying the site; b a kind of surveying that can produce a plan containing only the configuration of the site; c inspection of the site, clearing of it, comparing previous plans and maps with the site; |
| 4Recognaissance of the site is 5 Field work is 6 Office works are | d collecting plans and maps that carry information from the previous surveying; e calculation analyze of surveys, making up plans in drawing ink with the conventional signs and according to the given scale; f the technique and science of accurately determining the terrestrial or three-dimensional space position of points and the distances and angles between them. |
Leveling
Elevation
The line of a freely suspended thread supporting a weight indicates the line of action of gravity forces and is called the vertical line.
Planes cutting this line at right angles are called horizontal planes and all the lines contained in such planes are horizontal lines. Any surface, forming everywhere right angles with the vertical, such as for instance the surface of still water, may be regarded as a datum surface and the distance of any point from this surface as measured along a vertical will represent the altitude or elevation of this point.
When the datum surface is arbitrary this distance is called elevation and is denoted by h but when the datum surface coincides with the ocean or sea-level these distance are termed altitude and are indicated by the letter H.
Leveling methods
The differences in elevations between points are found in process of leveling. In direct leveling the differences in elevation are determined by reading vertical rods at the horizontal line of sight.
Leveling methods:
1. Direct leveling from the midpoint.
2. Forward leveling.
3. Simple and differential leveling. Leveling with one setting of the instrument (station) is called simple. If it is needed to determine the difference in elevation between remote points, the leveling is performed from several stations and it is call differential.
4. Profile leveling and cross-section leveling.
In the process of leveling the points common for two neighboring station are called turning, and the others- intermediate points. In the case of differential leveling it is necessary to pay special attention to the turning points, since an error in determining elevation of a turning point will be transmitted to all the others.
As a result of leveling we obtain the profile along the center line of the future construction. Such leveling is called leveling along the line. Alongside with leveling along the line it is a practice to also perform cross-section leveling in representative spots.
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