Site Surveying Fieldwork 1


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Site Surveying Fieldwork 1

  3. 3. Objective: The objectives of this field work are: - To have a better understanding of the procedure for leveling. - To have experiences to the actual working environment on the site including uncertainty weather condition. - To have witness the usage of leveling equipment and apparatus on site. - To understand more about how to see the backsight (BS) and foresight (FS) of the field work - To have the ability to setting up the tripod and adjusting the staff bubble. - To understand how to see the reading in the leveling rods. - To have the knowledge of the rules of levelling - To have skills in using the auto meter level for correct reading - To increase the team working skills among group members. - To have the ability in recording data of the reading - To understand the type of error would occur when taking the reading. - To have skills in applying formulae in calculation.
  4. 4. Introduction: Site Surveying is one of the subjects that one required to study to become a Professional Quantity Surveyor. We have been assigned to carry out a fieldwork on the 20th of November in Taylor’s University Lakeside Campus at selected area. Our fieldwork is about leveling. Fieldwork is basically a practice that allows us to merge theory and skills learned in the lectures into the reality site. By having the chance of doing fieldwork, it will helps to gain better understanding on collecting and analyzing data. Other than that, it will also help us to develop observational and investigation skills and also teamwork and problem solving skills. Moreover, leveling is all about measuring the height of each station using the proper instruments and to have number scaled in the selected survey area. Leveling is a very simple and accurate method of measuring the height of each pinpoint and the site level which is commonly used in any other construction sites. Besides, the equipment that are needed in order to make a complete leveling involved the auto level meter or the theodolite, tripod and leveling staff aluminum. The accuracy of the leveling are all depending the setup of the instrument and also the reading on the theodolite. It is very important to setup the instrument appropriately so that there will be no errors. Each of the instrument shall be kept safely, correctly calibrated and be used and stored with care. In the nutshell, any horizontal line can be chosen as a datum for heights and for leveling. The height of a point is measured along the vertical above or below the chosen datum. The height of a point relative to a datum is known as its reduced level. Differential of leveling provides a means of measuring the height differences between the points accurately. A level is set up on a tripod and leveled so that the line of sight is horizontal.Level or horizontal lines are always at right angles to the direction of gravity. Last but not least, we were given a benchmark as a starting point at the basement car park of the university. Then, we started to our task at the selected area and at the end of the survey we will go back to the same benchmark as an end. After completing and collecting all the reading during our survey, we are required to analyze and do the correction and adjust to the accurate reduced level from what we have got with the data that we have collected.
  5. 5. Apparatus: Basically, we were doing leveling work in our 1st site surveying fieldwork. In order to finish this fieldwork, we need a tripod, a dumpy level, and some leveling staffs with a staff bubble attached on it in order to finish the leveling work. Tripod: A tripod is a portable three-legged frame, used as a platform for supporting the weight and maintaining the stability of some other object. A tripod provides stability against downward forces and horizontal forces and movements about horizontal axes. Automatic level: An automatic level, auto level meter, leveling instrument, or dumpy level is an optical instrument used to establish or check points in the same horizontal plane. It is used in surveying and building to transfer, measure, or set horizontal levels. The automatic level is set up on a tripod and set to a leveled condition using foot screws (leveling screws). Leveling staff with staff bubble: A level staff, also called leveling rod, is a graduated wooden or aluminum rod, which measure vertical distances with reference to a horizontal plane or surface. Leveling rods can be one piece, but many are sectional and can be shortened for storage and transport or lengthened for use. The staff bubble is to ensure that the staff is held vertically. Picture above shows a tripod.
  6. 6. Picture above shows a automatic level. Picture above shows some leveling staffs.
  7. 7. Results: BS 130.00 164.80 139.60 288.00 143.50 144.90 159.60 133.90 141.70 138.70 1584.70 FS Rise 146.30 159.50 117.70 197.40 144.50 141.00 89.00 328.40 137.60 122.80 1584.20 (0.50) Fall 16.30 5.30 21.90 90.60 1.00 3.90 70.60 194.50 4.10 15.90 212.30 211.80 (-0.50) R.L 100.00 83.70 89.00 110.90 201.50 200.50 204.40 275.00 80.50 84.60 100.50 (0.50) Remarks BM1 TP1 TP2 TP3 TP4 TP5 TP6 TP7 TP8 TP9 BM1 ∑ ∆ Misclosure = Measured height – Known height = 100.50 – 100.00 = 0.50 Reduce Level Adjustment: Measured R.L 100.00 83.70 89.00 110.90 201.50 200.50 204.40 275.00 80.50 84.60 100.50 Point BM1 TP1 TP2 TP3 TP4 TP5 TP6 TP7 TP8 TP9 BM1 Adjustment 0.000 0.050 0.100 0.150 0.200 0.250 0.300 0.350 0.400 0.450 0.500 Adjusted R.L 100.00 83.65 88.90 110.75 201.30 200.25 204.10 274.65 80.10 84.15 100.00
  8. 8. Discussion: In a group of five members, we are assigned to conduct auto-leveling around the campus. The place chosen is a point starting from Taylor’s basement car park which is near to a fire extinguisher hose and it continues to form a loop around the basement car park. The reduced level of the Bench-mark 100.00m is given to us by our lecturer, Sir Wong JeeKhai. As our group members consist of five persons, three persons are to confirm the reading from the auto level meter and moving the instruments together, one person collecting the data and one person is assigned to move the leveling staff to decided points. The procedures include observation, booking and reduction. The equipment we did not use here is the staff bubble and the measuring tape. First, we need to set up our tripod and the auto level meter. The height of the tripod can be adjusted to suit the height of the person taking the reading. We do not have a staff bubble as there is already one attached together to the auto level meter. All we had to do next is to adjust the auto level meter so that the air bubble can be situated inside the circle which indicates the level we are taking the reading is a flat surface. The person carrying the leveling staff will then situate the leveling staff at the fixed point which is the benchmark and first reading is taken. Consequently, the leveling staffs moved to another point and the reading which is the foresight is taken. Now, the tripod will be moved to another point and being set up at another point again to take the second back sight and foresight. This process is being repeated till the end of the loop when we get back to the first point, our bench-mark. Taking the first few reading was quite simple to us but as we went further our group faced some problems. We get confused when reading the data collected and get mixed up with the back sight and the foresight. Actually, these problems will be much easier if we had used a table to collect our data right from the first place. However, our group still managed to get things cleared up after a discussion which took us much time during this fieldwork. At first, our group was the first group but due to this confusion our group turns out to be the last group to end this fieldwork. Nevertheless, the great thing is that we still managed to finish this fieldwork successfully. Throughout this fieldwork, we had no intermediate sight. The readings we took are the back sight and the foresight. In order to minimize error, the length between the back sight and foresight to the leveling staff is encouraged to be as equal as possible. So, we try to keep it this way. This might be the reason why we have many set ups. We also choose to set up our instruments at safe and convenient places such as corners at the car park and side of the road. Here, this is important so that we can not only get stable readings as we will not have to move our instruments away and set up again due to the cars passing by but also prevent traffic congestion. After the fieldwork, we go through our data together and assign each other’s work
  9. 9. regarding our fieldwork report. During the process of arranging and calculating our data records, we had some discussion relating our data and of course there is presence of error. Based on our data, we found the loop disclosure regarding the reduced level which is calculated by deducting the known height from the measured height. So, the solution is to carry out the level loop adjustment so that the bench-mark of the closing agrees and it is a way of even error distribution. Each of the set ups have different adjustment as the disclosure is linearly distributed according to the number of set ups. After we did the level loop adjustment, we finally got our adjusted reduced level which agrees our known reduced level. Below are the formulae we used in calculation: 1. Loop Disclosure = Measured height – Known height 2. Adjustment per set up = 3. Adjusted RL = Measured RL – Adjustments
  10. 10. Conclusion: From this field work we have learnt quite a few skills and have better understanding on how to do levelling. By doing the field work, we start to have better understanding on how to carry out the procedure for levelling and how to avoid or reduce the human error.Besides that, we are exposed to the actual working environment on the site such as the uncertainty of the weather which will enhance our experience and also witnessing the usage of levelling as well as the apparatus on site which allow us to be exposed regarding the apparatus used which makes our understanding better besides learning the theory in the lectures. Moreover, this field work also gave us a chance to use the knowledge from what we learnt in class and put into practice, such as use an automatic level to get the reading from a levelling staff. We also learnt how to carry a task out as a team by using more systematic way. In conclusion, this is one of a lifetime experience because as a quantity surveyor student this is rare occasion that we can learnt how land surveyor do and have better understanding on how they carry out their task.