CHAPTER 2

Question 1

is the procedure for determining
differences in elevation between points
that are some distance from each other

Answer 1

Levelling

Question 2

is the vertical distance above orbelow a reference datum.

Answer 2

Elevation

Question 3

What is the traditional vertical reference datum?

Answer 3

mean sea level (MSL)

Question 4

is a line from the surface of the earth to the earth’s center. It is also referred to as a plumb line or a line of gravity.

Answer 4

vertical line

Question 5

is a line in a level surface. A level surface is a curved surface parallel to the mean surface of the earth. A level surface is best visualized as being the surface of a large body of water at rest.

Answer 5

level line

Question 6

is a straight line perpendicular to a vertical line.

Answer 6

horizontal line

Question 7

is used to determine differences in elevation between points that are some distance from each other by using a surveyor’ level together with a graduated measuring rod.

Answer 7

Differential leveling

Question 8

All rod readings taken with a surveyors’ level contain an _________ over a distance K.

Answer 8

Error (c)

Question 9

When considering the divergence between level and horizontal lines, one must also account for the fact that all sight lines are refracted downward by the earth’s atmosphere. Although the magnitude of the refraction error depends on atmospheric conditions, it is generally considered to be about one-seventh of the curvature error.

Answer 9

CURVATURE AND REFRACTION

Question 10

is affected by atmospheric pressure, temperature, and geographic location but, as noted earlier, it is usually considered to be about one-seventh of the curvature error (c). If r = -0.14c, c + r = 0.0675K2, where K ≈ CA is the length of sight in kilometers.

Answer 10

Refraction (r)

Question 11

is a permanent point of elevation. BMs are established byusing precise leveling techniques and instrumentation

Answer 11

Benchmark (BM)

Question 12

is a semipermanent point of known elevation. They can be flange bolts on fire hydrants, nails in the roots of trees, top corners of concrete culvert headwalls, and so on.

Answer 12

Temporary benchmark (TBM)

Question 13

is a point temporarily used to transfer an elevation

Answer 13

Turning point (TP)

Question 14

is a rod reading taken on a point of known elevation to establishthe elevation of the instrument line of sight.

Answer 14

Backsight (BS)

Question 15

is the elevation of the line of sight through the level

Answer 15

Height of instrument (HI)

Question 16

is a rod reading taken on a turning point, benchmark, or temporary benchmark to determine its elevation

Answer 16

Foresight (FS)

Question 17

is a rod reading taken at any other point where the elevation is required

Answer 17

Intermediate sight (IS)

Question 18

TYPES OF LEVELLING

Answer 18

SIMPLE LEVELLING
DIFFERENTIAL LEVELLING
PROFILE LEVELLING
RECIPROCAL LEVELLING
PEG TEST

Question 19

One set up of level. When the difference of level between two points is determined by setting the leveling instrument midway between the points.

Answer 19

SIMPLE LEVELLING

Question 20

is adopted when : (i) the points are at a great differenceapart, (ii) the difference of elevation between the points is large, (iii) thereare obstacles between the points. To find elevation of non-intervisible points.

Answer 20

DIFFERENTIAL LEVELLING

Question 21

is generally adopted to find elevation of points along a linesuch as for road, rails or rivers etc. In this case, readings of intermediatestations are taken and reduced level of each station is found. From thiscross section of the alignment is drawn.

Answer 21

PROFILE LEVELLING

Question 22

When it is not possible to locate the leveling instrument in between the inter visible points, reciprocal leveling is performed. This case appears in case of ponds or rivers etc

Answer 22

RECIPROCAL LEVELLING

Question 23

The purpose of the _________ is to check that the line of sight through the level ishorizontal.

Answer 23

PEG TEST