MAPUA INSTITUTE OF TECHNOLOGYMuralla St, Instramuros, Manila, Metro ManilaSurveying Department

ELEMENTARY SURVEYING FIELD MANUAL

FIELD WORK NO. 10:AZIMUTH TRAVERSE USING THEODOLITE AND TAPE

CE120-2F/A2

MANALO, Ervin Jonzeth DR.2014180071Group 5

SEPTEMBER 12, 2015 / SEPTEMBER 17, 2015

Prof. Bienvenido Cervantes

OBJECTIVES:

1. To acquire knowledge in getting the area of a rectilinear field by staking station on each corner points on a piece of land.2. To learn how to read the horizontal angle of a theodolite.3. To learn how to perform a closed azimuth traverse survey using theodolite and tape.4. To develop the ability to lead or to follow the designated/desired task of ones party or group and to be fully responsible in the performance of the assigned task. INSTRUMENTS: THEODOLITEA Theodolite is a surveying instrument with a telescope that is used to measure the horizontal and vertical angles of the ground form a chosen point. A compass is included to determine the orientation of the instrument.

TRIPODA tripod is a portable, three-legged frame, used as a platform for supporting the weight and maintaining the stability of the optical surveying instruments.

LEVELING RODThe leveling staff, or leveling rod, is a graduated aluminum rod, used with a levelling instrument to determine the difference in height between points or heights of points above a datum surface.

PROCEDURE:

The professor assigns the corners of the rectilinear field to be observed. These points must be visible from each adjacent point and must be accessible for setting the instrument. Mark each point of the lot by chalk on pavement. Name the points as stations 1, 2, 3 etc. Set- up the theodolite on the 1st station. Orient the instrument to the magnetic south after leveling. Make sure that the tubular and bulls eye spirit level are correctly calibrated to minimize errors. Set the horizontal vernier to zero reading. Sight the next corner station and record the azimuth reading in the horizontal vernier. Compute also for the bearing of this line.Figure 1: The bulls-eye level and tubular level must be in the middle to ensure that the instrument is calibrated.

Sight the last station and record the reading of the horizontal vernier for its back azimuth to be used for checking the traverse later.Figure 2: Horizontal angle sighting using the theodolite.

Follow the same procedure until the last station is reached.

DATA SHEET

TABLE

STATIONLEVEL PROFILEANGLEANGLE OF DEPRESSIONHORIZONTAL DISTANCE

11.26m197116.48m

21.305m1578.98.33m

31.35m32713.55.62m

41.42m337810.10m

51.1125m32987.92m

COMPUTATIONS

The only computed quantities in the data are the bearing, and the horizontal distances because its more accurate to compute than to actually measure the length using measuring tapes that can sometimes sag and give inaccurate readings.

DATA ANALYSIS

The closed azimuth traverse that was performed in this field work had a slight variation from what the manual instructs. Instead of using tape measures and range poles, only a theodolite, leveling rod, and chalk is used to accurately gather data. The tape measure was removed from the list because it may give wrong measurements due to the fact that it sags and requires a great amount of pull to be accurately aligned with the ground. Instead, the more convenient way of measuring is used, which is computation via use of right triangles. Aside from that, all other procedures are done by the book. The azimuth traverse was gathered in each station by the use of the theodolite that is properly calibrated and oriented. Figure 3: The lot in front of the research building is the one that was used to survey.

As you can see above, this is the closed traverse that was marked and measured with corresponding sides/stations colored differently.

CONCLUSION

Using this method is easier compared to others. By its definition, Traverse is a method in the field of surveying to establish control networks. It involves placing survey stations along a line or path of travel, and the using the previously surveyed points as a base for observing the next point. It has many advantages, including:

Less reconnaissance and organization needed In other systems, which may require the survey to be performed along a rigid polygon shape, the traverse can change to any shape and thus can accommodate a great deal of different terrains. Only a few observations need to be taken at each station, whereas in other survey networks, a great deal of angular and linear observations need to be made and considered. Scale error doesnt add up as the traverse is performed. Azimuth swing errors can also be reduced by increasing the distance between stations.