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surveying > levelling > Flashcards

levelling Flashcards

1
Q

the process of directly or indirectly measuring vertical distances to determine the elevation of points their difference in elevation

A

Levelling

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2
Q

It is a curved surface which is at any point perpendicular to the direction of gravity or the plumb line.

A

Level Surface

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3
Q

a curved line in a level surface all points of which are normal to the direction of gravity and equidistant from the center of the earth.

A
  1. Level line
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4
Q

It is a plane that is tangent to a level surface at a particular point

A
  1. Horizontal surface
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5
Q

A vertical line at any point is a line parallel to the direction of gravity.

A
  1. Vertical line
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5
Q

A straight line in a horizontal plane which is tangent to a level line at one point.

A
  1. Horizontal line
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5
Q

A vertical line at any point is a line parallel to the direction of gravity.

A
  1. Mean sea level
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6
Q

any convenient level surface coincident or parallel with the mean sea level to which elevation of a particular area are referred.

A

Datum

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7
Q

an imaginary surface of the sea which is midway between high and low tides.

A
  1. Mean sea level.
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8
Q

the vertical distance above or below mean sea level or any other selected datum.

A

Elevation

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9
Q

the vertical distance between the two level surface in which the points lie.

A

Difference in elevation.

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10
Q

Direct leveling is the commonly employed method of determining the elevation of points some distance apart by a series of set ups of a leveling instrument along a selected route.

A

Direct or spirit leveling.

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11
Q

the process of accurately determining the difference in elevation between two intervisible points located at a considerable distance apart and between which points leveling could not be performed in the usual manner.

A

Reciprocal leveling.

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12
Q

This method of leveling is used to determine differences in elevation between points at designated short measured intervals along an established line to provide data from which a vertical section of the ground surface can be plotted

A

Profile leveling

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13
Q

This method of leveling is employed in determining by trigonometric computations the difference in elevation between two points from measurement of its horizontal or slope distance and the vertical angle between the points.

A

Trigonometric leveling.

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14
Q

combines features of direct leveling with those of trigonometric leveling.

A

Stadia leveling.

15
Q

determination of differences in elevation between points by measuring the variation in atmospheric pressure at each point by means of a barometer.

A

Barometric leveling

16
Q

In highway or railroad constructions it is often necessary to obtain a representation of the ground surface on either side of the centerline.

A

Cross-section leveling

17
Q

a method of determining the relative elevations of points in borrow-pit excavations for the purpose of calculating volumes of earthwork.

A

Borrow-pit leveling

18
Q

the most widely used direct leveling instrument.

A
  1. Dumpy Level
19
Q

has a detachable telescope which rests in supports called wyes. It can be removed from the Y-shaped supports and turned end for end during adjustment by releasing the two clapping collars which fit across the tops of the Y’s.

A

Wye Level.

20
Q

The instrument is used primarily in the different phases of the building construction where a high degree of precision is not a primarily requisite.

A

Builder’s Level

21
Q

often called a construction level or an architect’s level. The level vial is not as sensitive as in other levels and its telescope has a much lesser magnifying power.

A

Builder’s Level.

22
Q

This type of level has become popular for conventional leveling work because of the ease and speed of their operation. It does not use a level vial and its stability to level itself depends upon the action of a complex pendulum-and-prism device.

A

Automatic Level

23
Q

optical surveying instrument used for leveling. It is characterized by having a tilting telescope on a pivot.

A

Tilting Levels.

24
Q

Leveling of a high order of accuracy, usually extended over large areas, to furnish accurate vertical control for surveying and mapping operations.

A

Geodetic leveling

25
Q

tripod. Transit levels are used mainly for surveying and building, but they can be used to determine the relative position of lines and objects as well

A

Transit as a Level

26
Q

a control tool consisting of a rotating laser beam projector that can be affixed to a tripod. The tool is leveled according to the accuracy of the device and projects a fixed red or green beam in a plane about the horizontal and/or vertical axis.

A

Laser level

27
Q

The hand level consists of a brass tube about 15 cm long having a plain glass objective and a peep sight eyepiece. On top of the tube is a small level vial reflecting through a prism which appears to move vertically when viewed through the eyepiece

A

Hand Level

28
Q

the process of determining the difference in elevation between two or more points some distance apart.

A

Differential leveling

29
Q

is a fixed point of reference whose elevation is either known or assumed.

A
  1. bench mark
30
Q

is a reading taken on a rod held on a point of known or assumed elevation.

A

backsight

31
Q

A reading taken on a rod held on a point whose elevation is to be determined

A

Foresight (FS)

32
Q

is measured from the center of the instrument to the rod on which a backsight is taken.

A

Backsight distance (BSD)

33
Q

The horizontal distance from the center of the instrument to the rod on which a foresight is taken

A

Foresight distance (FSD)

34
Q

an intervening point between two bench marks upon which point foresight and backsight rod readings are taken to enable a leveling operation to continue from a new instrument position.

A

Turning point (TP

35
Q

the elevation of the line of sight of an instrument above or below a selected reference datum.

A

Height of instrument (HI)

surveying (2 decks)

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