The azimuth from station A of a link traverse to an azimuth mark is 212-12-36. The azimuth from the last station of the traverse to an azimuth mark is 192-12-15.
Line AB's extension through B has the same azimuth as line AB. Because the deflection angle to line BC is measured from the extension of line AB, the azimuth of line BC is the azimuth of line AB plus the deflection angle: Since the azimuth exceeded 360°, it is normalized by subtracting 360° from it.
Steps for determining correct bearing and true bearing of the given closed traverse Step 1 : Plot the traverse with the help of scale and protractor. ( Plot traversing with only fore bearings and then locate back bearings) The presence of local attraction at any station may be detected by observing the fore bearing and back bearing of the line.
From Section 9.7, paragraph 4: "A closed-polygon azimuth traverse is checked by setting up on the starting point a second time, after having occupied the successive stations around the traverse, and orienting by back azimuths. The azimuth of the first side is then obtained a second time and compared with its original value.
Because the deflection angle to line BC is measured from the extension of line AB, the azimuth of line BC is the azimuth of line AB plus the deflection angle:
When a bearing angle exceeds 90°, the line crosses into the adjacent quadrant. Line MN's correctly written bearing is S 88°54'15" E
Continuing to line CD, we use the same logic: New azimuth = previous azimuth + deflection angle
After angles are balanced by whatever method selected, the direction of each traverse line must be determined.
Many survey texts use a tabular approach to compute traverse line directions from angles. For the beginner this can be confusing and lead to erroneous directions. It helps to instead draw sketches in order to visualize the line relationships.
Subtract it from 93°38' to obtain next bearing angle .
Subtract it along with 87°42' from 180°00' to get bearing angle CD.
Typical precision: 1/5,000 for rural land, 1/7,500 for suburban land, and 1/10,000 for urban land
No error in corrected latitudes and departures
In this system, the bearing of the survey line is measured from eastward or westward from North or South whichever reference meridian is nearer and bearings are taken either in a clockwise or anticlockwise direction depending on the location of the line.
The horizontal angle between the reference meridian (North or South) and the survey line drawn from the station in a clockwise or anticlockwise direction based on the designation of angles with horizontal is known as a bearing. It is classified into two types i.e. Fore Bearings (F.B.) and Back Bearings (B.B).
The presence of local attraction at any station may be detected by observing the fore bearing and back bearing of the line. If the difference between fore bearing and back bearing is 180, then both end stations are free from the local attraction. If not, the discrepancy may be due to
Closed traversing is generally used for locating the boundaries or for surveying of large areas. b. Open Traverse: If a traverse starts and finishes at the points other than the starting point of known coordinates, then such traverse is known as an open traverse. An open traversing is generally used for preliminary and construction surveys ...
Traversing can be done in several methods based on instruments used for surveying to find linear measurement and direction of lines. Some of the methods are as follows:
As survey line DE and EA have a 180° difference. They are free from the local attraction. Now, we have to find the correct angle and bearings of survey line AB, BC, and CD.
The series of connected straight lines each joining two points on the ground is called a Traverse. Endpoints are traverse stations whereas straight lines between two consecutive stations are known as Traverse legs.
The azimuth from station A of a link traverse to an azimuth mark is 212-12-36. The azimuth from the last station of the traverse to an azimuth mark is 192-12-15. Angles to the right are observed at each station: A 136-15-41, B119-15-37, C 93-48-55, D136-04-17, E108-30-10, F 42-48-03, and G 63-17-17. What is the angular misclosure of this link traverse?
From Section 9.7, paragraph 4: "A closed-polygon azimuth traverse is checked by setting up on the starting point a second time, after having occupied the successive stations around the traverse, and orienting by back azimuths. The azimuth of the first side is then obtained a second time and compared with its original value. Any difference is the misclosure. If the first point is not reoccupied, the interior angles computed from the azimuths will automatically check the proper geometric total, even though one or more of the azimuths may be incorrect."
The interior angles in a five-sided closed-polygon traverse were observed as a104-28-36, B110-26-54, C 106-25-58, D102-27-02, and E 116-11-15. Compute the angular misclosure. For what FGCS order and class is this survey adequate?
From Section 9.1, a closed traverse provides a mathematical method of checking the observations whereas an open traverse has no geometric nor mathematical checks on the observations.
The first traverse should show angles to the right that are interior angles, and the second should show angles to the right that are exterior angles.
From Section 9.4, paragraph 2: "Often the number of stations can be reduced and the length of the sight lines increased by careful reconnaissance. It is always wise to "walk" the area being surveyed and find ideal locations for stations before the traverse stakes are set and the observation process is undertaken.".
From Section 9.8, paragraph 4: "Mistakes in orientation can be minimized when a data collector is used in combination with a total station. In this process, the coordinates of each back-sight station are checked before proceeding with the angle and distance observations to the next foresight station. For example in Figure 9.1 (a), after the total station is leveled and oriented at station B, an observation is taken "back" on A. If the newly computed coordinates of A do not closely match their previously stored values, the instrument setup, leveling, and orientation should be rechecked, and the problem resolved before proceeding with any further measurements. This procedure often takes a minimal amount of time and typically identifies most field mistakes that occur during the observational process."