Target not centred Can cause observed angle to be too large or small. Use long sight distances to reduce effect on observed angles.
Improper use of clamps and tangent screws Practice in formation of good observing habits and familiarity with equipment will reduce these errors. Poor focusing One of the most common errors. Be sure parallax is removed before taking observation.
Avoid different operators during observation procedure. Overly careful sights This is a common beginner error. Take careful sights on targets, but do not redo procedure. Beginners tend to observe, then reobserve, then reobserve This process results in unsettling instrument and reducing pointing accuracy. Trust your eyes. I have learnt from this task on the methodology involved with setting out, how it is carried out, and what the necessary precautions which have to be taken are and at the same time the errors involved with setting out.
Uren and W. Price, a traverse is defined as a chain of straight lines which is used as a basis for the measurement of details. A traverse is produced and developed by measuring the internal angles and distances between points forming a boundary of the site.
We shall be measuring close traverse in this task, where area will be found of a piece of land. Each of these straight lines is called a traverse leg and each point is called a traverse station. Figure 2. The closed traverse is mostly used for locating the boundaries at lakes, woods, or grasslands. They are mainly used for road constructions.
Fieldwork In a traverse, there are three stations which are considered to be of importance. The stations are referred to as the rear station, the occupied station and the forward station.
It is the starting point. Occupied station: it is the station at which the angle-measuring instrument is set up. This is the point which the person is measuring. Forward station: it is the next station which the person will measure in succession. During the traverse, the horizontal angles, vertical angles and horizontal distances are measured. Fig 2.
When measuring horizontal angles, the instrument is always sighted at the lowest visible point of the station markers designated the rear and forward stations.
It is done in order to avoid errors and have a more accurate drawing. Horizontal angles are used in determining bearings. Vertical angles: these are determined from instrument readings made at the occupied station to the height of instrument on the station marker using a staff at the forward station.
Vertical angles are used in determining the difference in height between stations. Distance: the distance was measured by using a 30 meters measuring tape. The distance is very important as it helps to determine coordinates and heights. From there, we take our first station reading. The stations were located in such a way that they were visible to the naked eye and visible during the measurement of the readings. The distances were measured using the measuring tape which was 30 meters long.
A taping team was set up whose job was to take the measurement between all the stations and record the measurement into a piece of paper. The line between stations was cleared of obstacles so that there is no interference. The traverse legs or stations were kept at a distance of more than 5 meters and less than 30 meters apart so that there will be less errors in azimuth and instrument centering and pointing.
Abubakar alkali kori, Ziyadah and Hasan Arbabi formed the taping team who set up all the stations and measured the distance using the measuring tape. Price Station markers Traverse stations were marked by using nails and spray paints.
All the stations were marked using the letters A, B, C etc and the exact point was marked using the spray paint and nail. Station signals Spray paint and long wooden sticks were used to mark the stations and a sketch was drawn in order to understand the area of the boundary. A total station is defined as a device which in combination with a theodolite and an EDM together with an inboard computer or microprocessor, has the capacity to perform various computations such as determining the horizontal and vertical components of slope distances, computing elevations and coordinates of sighted points.
It is set up on a tripod and a staff is used to take the measurements. The staff bubble should be accurately centered in order to obtain a highly accurate reading. After use, all the equipment used should be carefully stored with care. Price Care of Auto Levels If the instrument becomes wet leave it unpacked. Wipe down instrument, clean and dry transport case. Pack up instrument only when it is perfectly dry. Never touch the glass with fingers, use soft clean lint-free cloth to clean lens.
Place two matching level rods or two pieces of strapping in the ground about 15 meters apart with the faces toward each other. Position and level the instrument so that the distance from the instrument to each rod is the same measure. The error needs to be corrected by a competent repair technician. In our case, parallax error was avoided by using two different group members; they moved their eyes to different parts of the eyepiece when viewing the staff held by another group member.
The height of the instrument used is 1. First, we set up the bench mark. By referring to it, we placed the tripod on the ground and opened its legs. We first placed two legs into the ground and then the third one. Each of them were equally apart from each other roughly. We placed the theodolite on top of the tripod and then centred the bubbles to obtain accurate readings. Adjust recital until crosshairs are clear.
We remove the black casing from the front lens and then switch on the theodolite. We reset it to zero. The nail with the spray paint is seen using the lens on the ground and until it is visible, the theodolite is then set up to be used. We take the reading of the bench mark and the point 20 from behind. We then set it to zero again and take the point number 2 in front.
We take the horizontal distance by using the measuring tape. Every group member was assigned a different role in order to complete the task on time and more accurately. After doing the calculations, the angles were re-aligned while maintaining the same distance due to errors. The back bearing is defined as the angle from the south line of the same point.
My passport number is so the last two digits are The WCB is converted to radians form which is found using the formula below. The calculator is changed from degrees to radians. The arithmetic checks must be done for all levelling calculations. The HPC method of calculation can be much quicker when a lot of intermediate sights have been taken and it is a good method to use when mapping or setting out where many readings are often taken from a single instrument position. A disadvantage of the HPC method is that the check on reduced levels calculated from IS can be long and there is a tendency for it to be omitted.
Errors Instrumental - Plate level vial out of adjustment Detection: Level instrument in two directions as per typical setup. Any miscentering indicates that the plate level vial axis is not perpendicular to the vertical axis. Errors caused by peripheral equipment — Be sure that tripods, tribrach, and targets are mechanically sound and in adjustment.
Temperature Can cause uneven expansion of tripod and instrument parts resulting in instrument mislevelling. Most total station instruments have sensors to suspend observations when misleveling becomes to great.
Personal errors- Instrument miscentering Can cause observed angle to be too large or small. Target miscentering Can cause observed angle to be too large or small.
Beginners tend to observe, then re observe, then re observe In our site work carried out at Lanjut Resort, I believe the collimation error was avoided to its acceptable limits since we kept sight lengths equal, especially focusing on the BS and FS. A two peg test was also carried out in order to check the collimation error. We first placed pegs on both sides of the total station and then found the difference in elevation.
Then, we moved the level 30cm past both pegs and then took the readings again. There was a slight difference in elevation from both readings and it was concluded that it is in the acceptable range. In our case, the compensator was functioning perfectly since the total station used was in good condition. In our case, parallax error was avoided by using two different group members, they moved their eyes to different parts of the eyepiece when viewing the staff held by another group member.
Another error which arises from staff defects is the zero error. It usually occurs when two staffs are used for the same series of readings, and it is advised to use only one staff for all the readings which is what we followed for our tasks. The staff is held vertically straight as well since we are measuring the vertical height of the ground.
The staff was inserted into soft sand which is why there was trouble keeping the bubble on the centre for long since the sand kept the total station and the staff move a little.
To keep the accuracy in the readings, the measurement was taken quickly. To avoid this, a circle was made around the tripod and no one was allowed to enter the circle except the one using the total station. Fingertips were used to focus the total station and not the complete hand. There were a lot of errors and mistakes in this task but it was successfully completed and such a small margin of error states that from a student of civil engineering, we are on the right verge.
We worked as a team for this task and everyone was given different tasks to complete. My skills for working as a team were tested for this task. We all made new friends and got closer to each other individually then we were before. The best part was that I learnt a lot from this task. It improved my knowledge on whole circle bearing, how to obtain mean, and how to draw a closed traverse using pen and paper and in autocad.
The autocad part was very challenging in the beginning but slowly as I managed to see some videos on You Tube and learn from the Auto Cad help section, I managed to make the drawings required for this task. The figure is provided and the task was to produce the same figure on the beach and then measure the face right and face left and levelling measurements from stations 1, 2 and 3. The readings were then used to calculate the mean, whole circle bearing, Northing and Easting and the x and y using last two digits of the passport number.
The height of collimation method and rise and fall method were used for the levelling calculations. This report will explain the research methodology used, procedure, data, analysis of data, discussion, conclusion, recommendation and reference and appendix in the order stated.
The circular bubble on the upper part of the theodolite is now adjusted till it is centered by adjusting the individual tripod legs. A total station can measure both horizontal and vertical distances and at the same time the slope distances.
Using the vertical angle, the total station can calculate the horizontal and vertical distance components of the measured slope distance and display these. The instrument is pointed towards the reflector and part of the signal returns and is processed and in a few seconds, gives the slope distances with the horizontal and vertical distances. After this, since our XY was 50, the next point was north The measurements of face right and face left were taken at every point until the whole figure was sketched out at the field using the wooden pegs and the rope was used to connect all the points.
The auto level was used to carry out the levelling measurements at every point as one group member was holding the staff. This was done using height of collimation method and rise and fall method. The first bench mark was taken as plus last two digits of my passport number. Since my passport number is, the TBM remained as Microsoft excel was used to insert the data and do the calculations.
The error obtained is divided by the number of stations and then the value is distributed over the stations. Rise and Fall Method For the rise and fall method, there is also an arithmetic equation provided which can show us whether the equation used is correct or not.
The staff was held vertically straight as well since we are measuring the vertical height of the ground. Price The total station. Berger Sons Errors Instrumental - Plate level vial out of adjustment Detection: Level instrument in two directions as per typical setup.
Axis of sight not perpendicular to horizontal axis This error cause the telescope to scribe out a cone when it is plunged. Circle graduation errors — Caused by irregularities in marking of plates. Berger Sons Natural errors - Wind Vibrates tripod and target in windy condition. Berger Sons Tripod setting Avoid situation where legs are placed on different surfaces, and extreme soft-ground conditions. Most total station instruments have sensors to suspend observations when misleveling becomes too great.
Berger Sons Improper use of clamps and tangent screws Practice in formation of good observing habits and familiarity with equipment will reduce these errors. The different sources of error were discussed in order to explain how surveyors encounter the different errors and the best part was that most of the errors we had experienced them at the surveying camp so it gave us a very good description and made it easy for me to explain on the errors section.
The Contour lines came out properly and they do not meet which is an essential requirement in contour drawing. The Points seem to be parallel to each other. The survey is carried out in order to establish the points required and to ensure that the road is properly produced. Now the making of a road curve involves extension of the tangent lines. You can understand the drawing properly by checking the figure below: We are carrying out the survey in order to check the health and safety issues involved with the road.
If the proper dimensions are not used, even a small margin of errors can cause accidents which can cost us human lives and damage of infrastructure and vehicles. In other words, it can be the reason of major transportation crisis. This is why highway engineering is respected by the whole engineering society because they hold one of the most difficult jobs in the world and even a slight error is not affordable. Levelling screws use left-thumb rule. That is, bubble moves in direction of left thumb, right thumb should move in opposite direction.
Variable humidity can cause legs to swell. This will sometimes "lock" screws in place causing permanent damage to tripod. This will prevent you from having to lean over legs in most instances. You can use a coin or stone to check centring. Drop it from the centre of the tripod and observe where it hits. Make sure tribrach is centred on tripod head to ensure maximum flexibility in centring. Make sure parallax is removed. If not, repeat steps. Be careful not to rotate instrument when sliding on head of tripod.
If it takes more than the first attempt, you are doing something wrong! Example A chaining pin is used as a site on a station that is ft from the instrument. You may also want to record the water level in the cross-section you are surveying. If you do record the water level, be sure to note the date and time, as water levels vary with time. At the conclusion of your survey, you may wish to install monuments if you plan to re-survey in the future.
You may also want to photo-document your cross-section which will aid in drafting your cross-section. This ensures that no errors are introduced in your survey as a result of movement of the auto level. This same process is repeated for other cross-section locations or other types of elevation surveys such as a longitudinal profile surveys.
As such, comments and suggestions of improvement for this document are greatly appreciated. Please forward all ideas to Rune Storesund, P. Project: Date: Page 2 of 2. Open navigation menu. Close suggestions Search Search. User Settings. Skip carousel. Carousel Previous. Carousel Next. What is Scribd? Explore Ebooks. Bestsellers Editors' Picks All Ebooks.
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Jump to Page. Search inside document. Auto Level Surveys R. Procedure Before starting your field work, you will want to conceptually map out how many cross-sections and the extents of the cross-sections you may need, the extents of your longitudinal survey, and any other physical measurements that will benefit your subsequent analyses.
Storesund February The auto level survey will then be accomplished via the following steps: 1. Figure 1 — Use of a temporary turning point to maneuver around visual obstructions.
Storesund February 6. Figure 4 — You will want to keep track of your survey points in a field log. Munawwar Ismail. Qedew Er. Eng Ravi Kant Sharma. Anonymous QHfIVes9r. American Enterprise Institute. Tanuj Mathur. Francisco De Real Onde. Balaji Raj. Nicole Guillermo. Herbert Hillary Booker 2nd. Athiyo Martin.
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