Angles I

Question 1

Whats is a theodolite? (3)

Answer 1

1) Measures angles in the horizontal and vertical plane
2) Basically, two circular protractors (one in the horizontal plane, one in the vertical plane) + telescope and cross hairs.
3) Can be optical or digital.

Question 2

What is a total station? (3)

Answer 2

1) A modern-day incarnation of a theodolite
2) As a theodolite, measures horizontal and vertical angles.
3) Also capable of capturing distance measurement- Electromagnetic distance measurement (EDM).
4) Data logging and other features.

Question 3

What are theodolites and total stations summed up as?

Answer 3

Precise scientific instruments.

Question 4

What should hold true in a perfectly adjusted theodolite? (3)

Answer 4

1) Vertical axis should be truly vertical and perpendicular to the plate bubble.
2) Line of collimation (line of sight) should be perpendicular to trunnion axis.
3) Trunnion axis should be perpendicular to vertical axis.

Question 5

What do theodolites and total stations consist of?

Answer 5

Both consist of 2 360 degree protractors one in the vertical axis (horizontal plane) and one in the trunnion axis (vertical plane).

Question 6

What is the Sexagesimal system?

Answer 6

1 circle= 360 degrees
1 degree= 60’
1’=60’’ (where (‘ means minute and ‘’ means seconds)

Question 7

What is the Centesimal system?

Answer 7

1 circle = 400 gon

Question 8

How many radians are in a full 360 degrees?

Answer 8

2pie radians

Question 9

How do we measure horizontal angles?

Answer 9

Observe directions and compute bearings.

Question 10

How do we measure vertical angles?

Answer 10

Observe zenith angles and reduce to angles of elevation and depression, e.g. when trigonometrical heighting.

Question 11

What are modern day uses of TS and Theodolites? (3)

Answer 11

1) Volcano monitoring
2) Dam deformation
3) Met balloon tracking

Question 12

In surveying what is direction system based on?

Answer 12

Based on a bearing

Question 13

Define the bearing of a line.

Answer 13

It is the horizontal angle between it and a chosen reference direction (usually north).

Question 14

What is a bearing referred to?

Answer 14

True North which is called an Azimuth.

Question 15

What do surveyors use in terms of angles and why? (2)

Answer 15

Whole Circle Bearings (WCBs):

1) Standard way of defining bearings in surveying
2) Angle measured from 0-360 degrees clockwise from north.

Question 16

What type of mapping system do we use?

Answer 16

Use a set of axis where the x axis is the East axis therefore the x coordinate is the Easting and the y axis is the North axis therefore the y coordinate is the Northing coordinate.

Question 17

What may North be?

Answer 17

Grid N, True N or Magnetic N.

Question 18

Define Grid North.

Answer 18

Direction of the north to south grid lines of reference system (usually in Engineering Surveying).

Question 19

Define True North.

Answer 19

Direction of a meridian of longitude which converges on the North Pole, sometimes called geodetic north of geographic north.

Question 20

Define Magnetic North.

Answer 20

Direction of the north magnetic pole.

Question 21

System origin may be?

Answer 21

May be Local or National.

Question 22

How do you set up a total station or theodolite?

Answer 22

Need to centre the total station accurately over a station mark and level the instrument.

Question 23

What is the procedure of setting up a total station? (6)

Answer 23

1) Extend the tripod legs
2) Grasp two legs and spread roughly 1m apart and make and triangle with the other.
3) Ensure the tripod head is approx level
4) Fix the instrument to base of tribrach
5) Centre coarse bubble of tribrach
6) Now use fine levelling procedure to finalise centring and levelling

Question 24

What is fine levelling procedure? (5)

Answer 24

1) Turn the total station until plate bubble is parallel to two tribrach foot screws.
2) Turn foot screws until plate bubble is centre.
3) Bubble will move in the direction your left thumb
4) Turn the instrument 90 degrees and using only the foot screws that has not yet been used, bring the bubble centre.
5) Finish centring by sliding instrument on tripod as process will have moved the tribrach cross hairs slightly off survey mark

Question 25

What do WCB’s allow us to use?

Answer 25

Use of universal formula.