Traverse
Topic
4
Traverse Survey
LEARNING OUTCOMES
By the end of this topic, you should be able to: 1. 2. 3. 4. 5. Outline the basic components of a theodolite; Carry out temporary adjustments of a theodolite; Compute and adjust a theodolite traverse; Compute coordinates for traversing; and Determine the nature of errors affecting the traverse work.
INTRODUCTION
Traversing is a form of a control survey that requires the establishment of a series of stations that are linked together by angles and distances. The angles are measured by theodolites, and the distances are measured conventionally by tapes or electronic distance measuring equipment. The use of theodolite in traversing surveys is very fundamental and has become one of the most common methods in geomatic engineering work such as: general purpose angle measurement; provision of control surveys; contour and detail mapping; and setting out and construction work. This topic will describe the construction and use of the theodolite in traversing. It will explain the traverse design and the procedures of computing and adjusting a
TOPIC 4
TRAVERSE SURVEY
51
traverse. The application of coordinates for point location will also be covered in this topic which will be very useful in civil engineering project.
4.1
THEODOLITE PRINCIPLES AND APPLICATIONS
A theodolite is an instrument which is capable of measuring angles to the nearest whole second [Figure 4.1]. This can be done for both vertical and horizontal angles. Vertical angles are required for the calculation of elevation of points for example the reduction of slope distance to the horizontal.
Figure 4.1: Atheodolite Source: SouthGeosystems
Horizontal angles are required to obtain the relative direction to a survey control station or points of detail. Basically there are two types of modern theodolite which are in use today. These are the: (i) (ii) Optical theodolite; and Electronic Digital theodolite.
Both types of instrument
4
Traverse Survey
LEARNING OUTCOMES
By the end of this topic, you should be able to: 1. 2. 3. 4. 5. Outline the basic components of a theodolite; Carry out temporary adjustments of a theodolite; Compute and adjust a theodolite traverse; Compute coordinates for traversing; and Determine the nature of errors affecting the traverse work.
INTRODUCTION
Traversing is a form of a control survey that requires the establishment of a series of stations that are linked together by angles and distances. The angles are measured by theodolites, and the distances are measured conventionally by tapes or electronic distance measuring equipment. The use of theodolite in traversing surveys is very fundamental and has become one of the most common methods in geomatic engineering work such as: general purpose angle measurement; provision of control surveys; contour and detail mapping; and setting out and construction work. This topic will describe the construction and use of the theodolite in traversing. It will explain the traverse design and the procedures of computing and adjusting a
TOPIC 4
TRAVERSE SURVEY
51
traverse. The application of coordinates for point location will also be covered in this topic which will be very useful in civil engineering project.
4.1
THEODOLITE PRINCIPLES AND APPLICATIONS
A theodolite is an instrument which is capable of measuring angles to the nearest whole second [Figure 4.1]. This can be done for both vertical and horizontal angles. Vertical angles are required for the calculation of elevation of points for example the reduction of slope distance to the horizontal.
Figure 4.1: Atheodolite Source: SouthGeosystems
Horizontal angles are required to obtain the relative direction to a survey control station or points of detail. Basically there are two types of modern theodolite which are in use today. These are the: (i) (ii) Optical theodolite; and Electronic Digital theodolite.
Both types of instrument