Surveying is the art of measuring distances, angles and wide variety of surveying problems. • What is that range over a narrow but long strip of land. This manual provides basic concepts about surveying and is intended for use in This manual presents basic principles and practices of surveying for highway. the survey in which earth's curvature is neglected is called Plane surveying. Land survey: It involves measurement of various objects on land. This type of.
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BASIC SURVEYING - THEORY AND PRACTICE. Ninth Annual Seminar. Presented by the. Oregon Department of Transportation. Geometronics Unit. February. "Land surveyor" means a person who is engaged in the practice of land surveying: "Practice of land surveying" means any service of work, the adequate . Land surveying is basically an art and science of mapping and measuring land. Boundary Survey: Made to determine the length and direction of land lines.
As altitude increases, the barometric pressure ie- air pressure of the atmosphere decreases. Nicholas Mutua. It is set up on a tripod and a staff is used to take the measurements. Systematic errors are those which may exist but whose pattern and effects are known, can be monitored and compensated for by application of appropriate corrections. Remember that the bearing is measured clockwise.
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: 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.
Objective The objective of carrying out this task is to carry out: 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. To make sure there are no mistakes done, the answer was checked using the following equation: 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 Correction: 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! When surveying with a compass, one must account for this difference and adjust appropriately.
This is discussed further in section 3. Since the compass always points in essentially the same direction, one can measure horizontal angles by determining the angle between the object that is being sighted, and Magnetic North. While this method is simple, it is only accurate to within a few degrees. This circle, which rotates on the vertical axis, allows the surveyor to determine the horizontal angle between any two points. As discussed in section 1. The angles for subsequent points can then be read off the circle once the scope is rotated to view the point or object.
Similar to the Autolevel, the surveyor must choose a backsight from which to measure angles. Some do not allow this adjustment and the backsight angle must be recorded and later subtracted from all other angles measured from that station.
Once the backsight has been established, the surveyor must simply read and record the horizontal angles of each desired point using the theodolite. The basic principle of the theodolite is illustrated in Fig XX.
To do this, a complete set of information must be gathered about each point. Combining the various methods discussed in this chapter is necessary to get the appropriate survey in the least amount of time with the equipment available. However, remember that you must use enough methods to ensure that you have gathered all the required data. For example, if you only record a horizontal angle to a point, but not the distance, you cannot locate it in the XY plane. Below is a list of combinations that can be used to complete the indicated survey.
It does not make sense to measure a horizontal angle to a precision of 10 seconds, and then pace the distance. But what if the surveyor cannot see all the required points or objects from one setup location? Or what if the location of the Station is unknown? This is where a Traverse will come in. A Traverse is simply a series of Stations that starts from a known location and extends to wherever the surveyor needs it to go.
Many times a traverse is along a road, path or river. Commonly a traverse is linear, that is the stations form a single line. Sometimes however, the traverse must branch off to cover other areas, similar to a fork in a road.
Many times, hubs are given a special symbol on the map of a completed survey and a traverse is displayed as a line of hubs. As stated above, hubs are semi-permanent markers. They may be lost or change location. A good surveyor should always double check the location of a hub if it has not been used recently. Control points are precise and permanent points or points on an object that can be found and relocated at a future time.
Multiple control points should be placed at each hub for two reasons: Control points are discussed further in Chapter 3, but some common ones are a nail in a tree called a Tree Bench Mark or TBM , plate embedded in a concrete slab, or an iron pipe buried in the ground.
The next hub to be used in a traverse is called a Foresight. The hub that was used previous to the one now being used is called a Backsight. Special care should be taken to record the location of the foresight as accurately as possible because all future points taken from that hub will depend on it. Sighting the Backsight is essentially the same as locating the Foresight, just in reverse. There are many advantages to doing a Closed Loop, usually.
This is done by comparing where the first hub is predicted to be, to where it is measured to be. Using all of the data from the Traverse, a surveyor should be able to predict the relative location of the first hub angle and distance from the Station, when occupying the last hub. In fact, a surveyor should be able to predict the location of the first hub from ANY hub, but this may be a very large distance.
Inevitably, these will not be the same. If the traverse has been done well, the difference in the locations will be off by a few centimeters. Traverse errors are generally expressed in centimeters or millimeters or inches. The finished product of a surveyor, that which is delivered to the client is NOT pages of numbers that represent the survey though this is important , it is the map that the data is used to produce, In this section there are a few tips and figures to give insight into the map making process.
Point objects are obviously those that can be defined by a single point, such as a tree, fence post, or boulder. If an object is linear, such as a road or stream, it can be defined by either determining its centerline and noting its width easier , or by recording both its edges.
Thus, if the stream or road is straight for a long distance, the points can be far apart, but if the object is curved, there must be enough points to define the curve.
Points defining a polygonal object will also be connected using straight lines. Thus, if picking up an object with straight sides like a building , it is best to locate the corners. For a square building, if the corners are roughly 90 angles, only three corners are necessary.
For circular objects like a water tank, at least 3 points are also required to define the circle. They can also be defined as lines perpendicular to the flow of water water always flows down hill in the steepest direction. Creating contour lines on a map is the easiest method to display the three dimensional topography of land. The surveyor should note that in general, a straight line will be drawn between two points and thus the contour lines will be evenly spaced.
Therefore, care should be taken to record enough points to define the topography. If a hill or grade has a constant slope, points only need to be taken at the top and bottom of the slope.
But if the slope is constantly changing, topography points must be taken at regular intervals,. One example of this is if a stream has a wide flat bottom and then high, steep banks. If the surveyor only records points at the stream centerline and top of the banks, then the stream will be recorded as a v- shaped ravine. However, if the surveyor records the edge of the stream at the bottom and the top of the bank, then the stream will be accurately recorded.
This can be seen in Fig XX. In addition, when conducting a 3D survey, it is important to remember that any objects that are picked up, such as buildings, also provide an elevation at that point. This may be necessary and useful, such as when locating the centerline of a road, or unnecessary. In some cases, the surveyor is interested in the.
These points should be noted as such in the field notes. Sections include how to keep a field notebook, setting up hubs, and taking various measurements. Thus, it is important to keep a neat and detailed field notebook.
All of your data, sketches, and notes need to be written down in your field notebook. Any notebook can be a field notebook.
Be sure to follow this format: Here is an example title page. Anything that is underlined would be changed according to what surveying work you are doing. Survey Field Notebook Location: North of the water source Project: T2 Theodolite Name: When you begin, you will only have one line in your index.
As you collect more data, you will be adding more lines to your index. You must write down as much as you can about what you are surveying. Recorded field notes consist of a combination of tabulated data, sketches, and descriptions. The total record of any survey in the field notebook should provide a clear and concise picture of the survey performed. This information will include descriptions of the starting and closing stations, a description of any principal station established, the area or locality in which the work is performed, the purpose of the survey, and general remarks on weather, terrain, or other conditions that may be factors in evacuating the results.
The information in the field notes must be complete enough that anyone not familiar with that particular survey operation can take the notebook, return to the locality, and recover or reconstruct any portion of the survey.
Note that the students recorded the date, location, and weather in the upper right hand corner. For example, W. Doolittle has an open book next to his name, so he was recording data. Rodgers was sighting tripod symbol. Evans and H. There are more examples of how to take field notes for different types of surveys e.
However, this will be covered in a later section Appendix E: More Field Book Techniques. Insert bayonet socket into bridge screw. Requirements for a good hub location are:. If placing a hub in a solid object, such as a tree, root, concrete or pavement, a nail will usually be sufficient. If placed in the soil, obviously a nail will not be immobile or easy to find again. Thus, the nail is usually placed in a wooded stake after the stake has been driven into the ground.
A bearing is the horizontal angle measured clockwise from north Note: The needle on the compass points to magnetic North. For our main purpose of measuring a horizontal angle between two points, it is easiest to just use magnetic north. Since both bearings will be compared to the same reference point magnetic north , this will not affect accuracy of the horizontal angle between points. This is called magnetic bearing. Remember that the bearing is measured clockwise. To determine the horizontal angle between two points, simply subtract the two bearings.
This difference will be the number of degrees between the two points, referenced from where you are standing. The following paragraph outlines how to do this. Accurately measure a pacing course on level ground. Repeatedly pace off the course, counting off the number of paces it takes to complete the distance. Keep a natural comfortable pace that can be held all day. It is easier to measure the number of paces per meter for example, 46 paces per meters than measuring number of meters per pace.
Measure your pace against different terrains and at different times of day, because your pace may change between the morning and afternoon or when walking on different terrains. There are many methods to keep track of the distance traveled when using the pace count. Some of these methods are: Do not try to remember the count; always use one of these methods or design your own method. Certain conditions affect your pace count in the field, and you must allow for them by making adjustments.
Your pace lengthens on a downslope and shortens on an upgrade. Keeping this in mind, if it normally takes you paces to walk meters, your pace count may increase to or more when walking up a slope. A head wind shortens the pace and a tail wind increases it. Sand, gravel, mud, snow, and similar surface materials tend to shorten the pace. Falling snow, rain, or ice cause the pace to be reduced in length. Excess clothing and boots with poor traction affect the pace length.
Poor visibility, such as in fog, rain, or darkness, will shorten your pace. The stadia distance SD is the distance between these two cross hairs. Another person takes the body of the measuring tape and walks to the next location.
The second person reads the number on the measuring tape and records the distance. Make sure to keep the measuring tape taut and measure the distance from the ground to where the tape is being held. When reading the tape, be sure to check the feet and inches markers twice. The "foot" markers are close to the "11th inch" marker and sometimes an extra foot is mistakenly added to the measurement.
You can make the graduated rod taller by extending or telescoping the inner tubes of it. Be sure to extended the largest diameter telescoping parts before the smaller diameter telescoping parts, otherwise the numbers will be off.
You can try this on your own and notice the difference between measurements when you extend different parts of the rod. From the vertical angle set up, the number on the graduated rod that falls between the crosshairs of the viewer is the vertical height. Both the number read from the rod and the height of the eyepiece of the scope should be recorded.
Tighten the upper plate such that the theodolite is locked to the lowering swiveling plate and proceed to point this to the reference object which you wish to measure the horizontal angle from. Land surveying has been a challenge for many years both in developed and developing countries.
For instance the triangular survey consumes a lot of time as several sides of the field need to be measured. We detail the derivation of this new formula as follows: Severally, over the past we have tried to come up with new formulae which could ease the complex arithmetic algorithms encountered while executing results for just simple arithmetic problems which mathematicians commonly face in their life. This seemed not to bear fruits as the modification made had no much contribution as advised by peers.
Our first attempt triggered off further efforts; further research was done to solve future surveying problems. It was not until on June while studying on curvilinear co- ordinates that we were prompted with an idea which enabled us to discover that the area of a triangle could be found by a relation connecting area to length of one side and trigonometric ratios of two angles emanating from the line considered.
The knowledge of Vector analysis, equation of straight lines and calculus all combined proved to be helpful in our formula derivation. A 1 A 3 y -intercept is zero. Here we are posed with a challenge of finding c y-intercept. Since the x-intercept is known i.