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LEC: Apply the basic surveying concepts, principles and theories on determining horizontal and vertical distances using stadia.
LAB: Apply the basic surveying concepts, principles and theories on stadia and topographic surveying as well as subdivision of lots.
MODULE 3: MEASUREMENT BY STADIA
STADIA
Stadia is a method of surveying in which distances and elevations are obtained by observing the interval on a graduated, upright rod called stadia rod intercepted by two parallel horizontal lines called the stadia hairs in a surveyor's transit set up at a distance from the rod (learncst.com). The stadia method is a fast and efficient way to measure distances in order to determine topographic details. When distances between traverse stations are determined by the stadia method, the resulting survey is called a stadia traverse.
Stadia is a method of surveying in which distances and elevations are obtained by observing the interval on a graduated, upright rod called stadia rod intercepted by two parallel horizontal lines called the stadia hairs in a surveyor's transit set up at a distance from the rod (learncst.com). The stadia method is a fast and efficient way to measure distances in order to determine topographic details. When distances between traverse stations are determined by the stadia method, the resulting survey is called a stadia traverse.
DEFINITION OF TERMS
Differential leveling is the process of determining the elevation of points some distance apart. It requires a series of set-ups of the instrument along the general route. For each set-up, a rod reading back to a point of known elevation and forward to a point of unknown elevation is taken. The rod reading taken on a point of known elevation is called a backsight (BS) or also known as plus sight while the rod reading taken on a point of unknown elevation is called a foresight (FS) or also known as a minus sight. Further, bench mark (BM) is a definite point on a permanent object of known elevation and location which serves as reference for leveling work. In surveying long-distance route, turning points are marked between the known and unknown elevation point. Turning point (TP) is an intermediate point between two bench marks upon which rod readings are taken. Height of Instrument (HI) is the elevation of the line of sight of the center of the cross-hairs in the telescope when the instrument is properly leveled. The height of instrument is equal to the elevation of the benchmark sighted plus the rod reading taken on the benchmark (HI = Elevation of BM + BS). Elevation is a vertical distance above or below an arbitrary assumed level surface or datum. In surveying, this arbitrary referenced datum is typically the Mean Sea Level (MSL). Elevation is computed by subtracting the foresight of the current station from the height of the instrument of the previous station (Elevation = HI - FS).
Differential leveling is the process of determining the elevation of points some distance apart. It requires a series of set-ups of the instrument along the general route. For each set-up, a rod reading back to a point of known elevation and forward to a point of unknown elevation is taken. The rod reading taken on a point of known elevation is called a backsight (BS) or also known as plus sight while the rod reading taken on a point of unknown elevation is called a foresight (FS) or also known as a minus sight. Further, bench mark (BM) is a definite point on a permanent object of known elevation and location which serves as reference for leveling work. In surveying long-distance route, turning points are marked between the known and unknown elevation point. Turning point (TP) is an intermediate point between two bench marks upon which rod readings are taken. Height of Instrument (HI) is the elevation of the line of sight of the center of the cross-hairs in the telescope when the instrument is properly leveled. The height of instrument is equal to the elevation of the benchmark sighted plus the rod reading taken on the benchmark (HI = Elevation of BM + BS). Elevation is a vertical distance above or below an arbitrary assumed level surface or datum. In surveying, this arbitrary referenced datum is typically the Mean Sea Level (MSL). Elevation is computed by subtracting the foresight of the current station from the height of the instrument of the previous station (Elevation = HI - FS).
Elevation is a vertical distance above or below an arbitrary assumed level surface or datum. Note that elevations are needed to set slope stakes, grade stakes, footings, anchor bolts, slabs, decks, sidewalks, curbs, and many other applications in civil engineering. In other words, everything located on the project site requires elevations. Determining elevation of some unknown points is the main objective of this field work. To attain this objective, differential leveling will be used. Differential leveling is a process of measuring the vertical distances from a known elevation point to find the elevation of unknown points. It requires the use of a surveyor’s level and a graduated measuring rod. The process is simply reading a rod held vertically on, first, a known elevation point called bench mark, and, second on the unknown elevation point. In surveying long-distance route, turning points are marked between the known and unknown elevation points to determine the elevation of the unknown point. These turning points will be the temporary known elevation to be used for the succeeding elevation.
This field work was conducted at Magarao, Camarines Sur on a rainy day. Despite the heavy rain, we still managed to finish our field work. I was the instrument man that time so I was the responsible for the rod readings taken on the transit. The distance we covered was 250m and we divided it into 14 stations since the allowed gap between station is at most 20m. We followed the mentioned formulas above in computing for the height of the instrument and the elevation. Note that in order to ensure the accuracy of the measurements, an arithmetic check should be done. The difference between the summations of the backsight and the foresight must be equal to the difference in elevation between the initial and final points of the level line.
FIELD WORK #5: DIFFERENTIAL LEVELING
Salazar_BSCE2B_Field Work #5.pdfREFLECTION
LEC and LAB: This module allowed me to learn how to use the optical level especially during the field work that I was assigned as the instrument man. Learning how to utilize it is a new skill unlocked for me since I know that I could use this skill for future purposes once I became an engineer. Furthermore, I also learned the importance of elevation in the civil engineering world. Elevations are needed to set slope stakes, grade stakes, footings, anchor bolts, slabs, decks, sidewalks, curbs, and many other applications in civil engineering. Elevation of a point can be determined by using a known elevation or bench mark. Just familiarize these formulas: HI = Elevation of BM + BS and Elevation = HI - FS since they are the repeatedly used during the computations. Also, the difference between the summations of the backsight and the foresight must be equal to the difference in elevation between the initial and final points of the level line to ensure that the measurements and computations made are precise and accurate. In case of a long-distance route, turning points must be marked in between the end points knowing that the maximum distance the optical level can read is 90 meters.
LEC and LAB: This module allowed me to learn how to use the optical level especially during the field work that I was assigned as the instrument man. Learning how to utilize it is a new skill unlocked for me since I know that I could use this skill for future purposes once I became an engineer. Furthermore, I also learned the importance of elevation in the civil engineering world. Elevations are needed to set slope stakes, grade stakes, footings, anchor bolts, slabs, decks, sidewalks, curbs, and many other applications in civil engineering. Elevation of a point can be determined by using a known elevation or bench mark. Just familiarize these formulas: HI = Elevation of BM + BS and Elevation = HI - FS since they are the repeatedly used during the computations. Also, the difference between the summations of the backsight and the foresight must be equal to the difference in elevation between the initial and final points of the level line to ensure that the measurements and computations made are precise and accurate. In case of a long-distance route, turning points must be marked in between the end points knowing that the maximum distance the optical level can read is 90 meters.
REFERENCES:
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