Land Surveying Civil Engineering and Architecture

Land Surveying Civil Engineering and Architecture
© 2010 Project Lead The Way, Inc.

Definition of Surveying in the State of Tennessee (T.C.A. 62-18-102)
Land Surveying Civil Engineering and Architecture Unit 3 – Lesson 3.4 – Site Considerations Definition of Surveying in the State of Tennessee (T.C.A ) Any service of work, the adequate performance of which involves the application of special knowledge of the principles of mathematics, the related physical and applied sciences, and the relevant requirements of law for adequate evidence to the act of measuring and locating lines, angles, elevations, natural and man-made features …for the purpose of determining areas and volumes, for the monumenting of property boundaries, and for the platting and layout of lands and subdivisions thereof, including the topography, drainage, alignment and grades of streets, and for the preparation and perpetuation of maps, records, plats, field notes, records and property descriptions that represent these surveys. Project Lead The Way, Inc. Copyright 2010

Famous Land Surveyors George Washington Thomas Jefferson
Land Surveying Civil Engineering and Architecture Unit 3 – Lesson 3.4 – Site Considerations Famous Land Surveyors George Washington Surveyor General in Virginia, 1749 Thomas Jefferson County Surveyor for Albemarle County, VA, 1773 Lewis and Clark Expedition to explore and survey the west Daniel Boone Resolved Kentucky land disputes Abraham Lincoln Surveyor in Illinois when elected to state legislature Project Lead The Way, Inc. Copyright 2010

Land Surveying Civil Engineering and Architecture Unit 3 – Lesson 3.4 – Site Considerations Land Surveying The science of determining the relative positions of points on the Earth’s surface. Geodetic Surveys Plane Surveys There are two categories of land surveys that require different surveying methods – geodetic surveys and plane surveys. Project Lead The Way, Inc. Copyright 2010

Land Surveying Civil Engineering and Architecture Unit 3 – Lesson 3.4 – Site Considerations Geodetic Survey Takes into account the true size, shape, and gravity fields of the Earth The geoid is the equipotential surface of the Earth’s gravity field which best fits global mean sea level Provides significant precision Establishes highly accurate control networks A geodetic survey is based on the true shape of the Earth. The true shape of the Earth is not a sphere but an irregular ellipsoid shape. Many models of the true shape of the Earth exist. One model, the geoid, is a model of the assumed mean sea level which is dependent on the gravitational forces around the world. The western hemisphere geoid is shown in the computer-generated model on the left. The yellow and orange areas are further from the center of the Earth than the blue areas. Geodetic surveys use the geoid or another similarly shaped model as a basis. These surveys are performed with great precision and are used to establish highly accurate control networks that provide points of known position throughout the US and the world. Images courtesy NOAA Project Lead The Way, Inc. Copyright 2010

Plane Survey Assumes the Earth’s surface to be a plane (flat)
Land Surveying Civil Engineering and Architecture Unit 3 – Lesson 3.4 – Site Considerations Plane Survey Assumes the Earth’s surface to be a plane (flat) More common than geodetic surveys Precise enough for small-scale surveys in a limited area, such as a construction site Used to determine legal boundaries, construction surveys, and small-area topographic or control surveys ©iStockphoto.com Project Lead The Way, Inc. Copyright 2010

Geodetic vs. Plane Survey
Land Surveying Civil Engineering and Architecture Unit 3 – Lesson 3.4 – Site Considerations Geodetic vs. Plane Survey Plumb Line Plane Survey Line of equal elevation Geodetic Survey Line of equal elevation Rod Rod Horizontal Plane Earth’s surface In a geodetic survey, the geoid is taken as the datum. Lines that indicate level surfaces undulate with the strength of the gravitational field. In a plane survey, the curvature the Earth is considered flat, and lines of equal elevation are assumed to be horizontal planes. In this class, we will perform plane surveys. Geoid or other Datum Project Lead The Way, Inc. Copyright 2010

Types of Surveys Control Survey Topographic Survey Property Survey
Land Surveying Civil Engineering and Architecture Unit 3 – Lesson 3.4 – Site Considerations Types of Surveys Control Survey Topographic Survey Property Survey Site Survey Construction Survey Project Lead The Way, Inc. Copyright 2010

Land Surveying Civil Engineering and Architecture Unit 3 – Lesson 3.4 – Site Considerations Control Survey Establish precise horizontal and vertical positions of points that serve as a reference for other surveys Control surveys are used to establish the latitude, longitude, and/or elevation of reference points that can be used for other types of surveys. The image here is published in the Seminole County Geodetic Control Points document (2006), which provides a description of the location of each control point in addition to the latitude, longitude, and/or elevation. These control points can then be used as a basis for topographic, construction, or other surveys. The photos show survey crew members setting survey marks during control surveys in Alaska. The black and white image was taken near White Pass, Alaska in The color photo is a more recent shot of a crew member mixing cement to set a mark in a rock in Southeast Alaska. Photos Courtesy NOAA Courtesy Department of Public Works, Seminole County, FL Project Lead The Way, Inc. Copyright 2010

Topographic Survey Land Surveying Civil Engineering and Architecture Unit 3 – Lesson 3.4 – Site Considerations Gathers data on the location of natural and man-made features, contours, and ground elevation to create a topographic map This is an example of a topographic map for the area surrounding Stowe, Vermont. The contour lines indicate lines of constant elevation. Courtesy USGS Project Lead The Way, Inc. Copyright 2010

Property Survey (or Boundary Survey)
Land Surveying Civil Engineering and Architecture Unit 3 – Lesson 3.4 – Site Considerations Property Survey (or Boundary Survey) Establishes property lines for a lot Used to create a plat This is an example of a recorded plat created from a property survey near Mount Pleasant, SC. The property lines are located using a length and a bearing angle. Project Lead The Way, Inc. Copyright 2010

Site Survey (Plot Survey or Lot Survey)
Land Surveying Civil Engineering and Architecture Unit 3 – Lesson 3.4 – Site Considerations Site Survey (Plot Survey or Lot Survey) Combination of a property survey and topographic survey May be required to receive a construction permit This site plan shows both property lines and contours from a topographic survey. Project Lead The Way, Inc. Copyright 2010

Land Surveying Civil Engineering and Architecture Unit 3 – Lesson 3.4 – Site Considerations Construction Survey Locates points and elevations that can be used to establish correct locations and elevations for engineering and architectural projects Examples of construction surveys include staking a line and grade for a foundation, a fence, or a road. In the picture, the string lines were laid out based on a construction survey. Notice the surveying equipment to the right in the picture used to ensure that the foundations are poured to the correct elevation. Courtesy Isle of Palms, SC Recreation Department Project Lead The Way, Inc. Copyright 2010

National Spatial Reference System (NSRS)
Land Surveying Civil Engineering and Architecture Unit 3 – Lesson 3.4 – Site Considerations National Spatial Reference System (NSRS) Common set of reference points for all surveys Horizontal Datum = Collection of points of known latitude and longitude Vertical Datum = Collection of points of known elevation Benchmark (BM) = Permanent mark that establishes a point of known elevation The top photograph is an example of a horizontal datum marker. The bottom photo shows a benchmark. Courtesy NOAA Wikimedia.org Project Lead The Way, Inc. Copyright 2010

Land Surveying Civil Engineering and Architecture Unit 3 – Lesson 3.4 – Site Considerations Reference System Data Information on datum points available at You can search for information on datum reference points on the National Geodetic Service survey control mapping service. This map shows the area near the Keystone Library Project in Noblesville, IN. The red points are datum reference points. Project Lead The Way, Inc. Copyright 2010

Example Data Sheet Land Surveying Civil Engineering and Architecture
Unit 3 – Lesson 3.4 – Site Considerations Example Data Sheet All of the information about a datum point is available on a data sheet. This example is from a point of horizontal and vertical control near the Keystone Project in Noblesville, IN (see the state/county information). The horizontal coordinates (latitude and longitude) are highlighted in blue. The vertical height above mean sea level is highlighted in yellow. Project Lead The Way, Inc. Copyright 2010

Optical Equipment Requires a visual line-of-sight
Land Surveying Civil Engineering and Architecture Unit 3 – Lesson 3.4 – Site Considerations Optical Equipment Requires a visual line-of-sight A level measures vertical differences in elevation. A theodolite measures vertical and horizontal angles. A total station is an electronic/optical instrument that combines a theodolite and an electronic distance meter (EDM) to measure distances. ©iStockphoto.com ©iStockphoto.com A theodolite measures vertical and horizontal angles A total station is an electronic/optical surveying instrument Project Lead The Way, Inc. Copyright 2010

Optical Equipment Automatic (Auto) Level
Land Surveying Civil Engineering and Architecture Unit 3 – Lesson 3.4 – Site Considerations Optical Equipment Automatic (Auto) Level Commonly used on building sites Internal compensator can automatically level the instrument An automatic or auto level is commonly used on building sites because it is easy to set up and use. Kennedy Measures difference in elevation between the line of sight and a point Project Lead The Way, Inc. Copyright 2010

Other Equipment Professional Tape Measure Field Book Leveling Rod
Land Surveying Civil Engineering and Architecture Unit 3 – Lesson 3.4 – Site Considerations Other Equipment Kennedy ©iStockphoto.com Professional Tape Measure Kennedy Other equipment often used in conventional optical surveys are a leveling rod, a tripod, a professional tape measure, and a field book. The tripod supports the surveying instrument. The tape is used to measure distances. The leveling rod is used to measure vertical distances with optical equipment and looks like an extra long measuring stick. The field book is used to record the measurements and observations taken during a survey. Courtesy USGS Kennedy Field Book Kennedy Leveling Rod Tripod Project Lead The Way, Inc. Copyright 2010

GPS Technology Global Positioning System
Land Surveying Civil Engineering and Architecture Unit 3 – Lesson 3.4 – Site Considerations GPS Technology Global Positioning System A global navigation satellite system Developed by the U.S. Department of Defense A constellation of satellites that broadcast radio signals Receivers intercept several satellite signals in order to determine precise location Courtesy NASA The GPS system can be used for surveying as well as navigation. The GPS system is a free-to-access system developed by the US Department of Defense. It consists of a constellation of many satellites that orbit the Earth, each broadcasting a unique radio signal. GPS receivers determine the distance to each satellite based on the time it takes the signal to reach the receiver. The location of the receiver on Earth can be determined from as few as three satellite signals. Multiple satellites are always accessible from any point on Earth at any time. The top picture is a NASA image of one of the GPS satellites. The bottom image shows a moment in time when a GPS receiver on Earth has access to 12 satellite signals. As the satellites orbit and the Earth spins, the number of visible satellites from a location changes. Widimedia.com Project Lead The Way, Inc. Copyright 2010

GPS Land Surveying Civil Engineering and Architecture
Unit 3 – Lesson 3.4 – Site Considerations Some recreational GPS navigation units only calculate horizontal position (latitude and longitude) and superimpose the location on a map image. These units do not need a high degree of accuracy and may calculate location to within a few meters – close enough to determine which road you are on. Other handheld GPS receivers, like the one pictured here on the right, provide both horizontal and vertical position in terms of latitude, longitude, and elevation. The accuracy varies with the unit. Professional grade GPS surveying equipment, like that shown in the left image, provides a much higher level of accuracy than the lower cost recreational units. It calculates both horizontal and vertical position to a high degree of accuracy. This surveyor is setting up GPS surveying equipment which includes an antenna, a GPS receiver, and a remote receiver. Kennedy ©iStockphoto.com Project Lead The Way, Inc. Copyright 2010

Auto Level Telescope Sight Mirror Diopter Adjustment Ring
Land Surveying Civil Engineering and Architecture Unit 3 – Lesson 3.4 – Site Considerations Telescope Auto Level Sight Mirror Diopter Adjustment Ring Bulls Eye Level Horizontal Tangent Knob Eyepiece Before using the Auto level, the instrument should be leveled so that when the instrument is rotated, the line of sight defines a horizontal plane. The leveling screws allow the surveyor to adjust the alignment of the instrument to provide a horizontal line of sight. If properly calibrated, the instrument will be level when the bubble in the bulls eye level is within the circle. The mirror will reflect the bulls eye level when viewing from the eyepiece height. The sight can be used to roughly align the telescope with the rod position. Rotation of the horizontal tangent knob results in a fine horizontal adjustment. When looking through the telescope, it will slowly adjust the view left to right. The horizontal rotation ring is used to approximate horizontal angles. Rotating the diopter adjustment ring, which surrounds the eyepiece, can sharpen the crosshairs when viewed through the eyepiece. Horizontal Angle Rotation Ring Leveling Screws Kennedy Project Lead The Way, Inc. Copyright 2010

Reading the Rod View through the telescope Beveled hatch marks
Land Surveying Civil Engineering and Architecture Unit 3 – Lesson 3.4 – Site Considerations Reading the Rod Beveled hatch marks Vertical crosshair Stadia hairs Horizontal crosshair Examine your rod to determine the increments used. On this rod, the red numbers indicate whole feet – and they actually measure a true 12 inches. Each foot is broken up into ten numbered divisions – the black numbers indicate tenths of feet. Each tenth is further divided into ten increments which are indicated by the edges of the hatch marks. You will have to get used to counting edges of lines instead of the lines themselves. The tenths of feet and measurements that end in 5 hundredths of feet are indicated by the long edge of a beveled hatch mark. Let’s try to make a rod reading (next slide). View through the telescope Project Lead The Way, Inc. Copyright 2010

Reading the Rod Rod Reading = 5.25 ft Upper Stadia Reading = 5.30 ft
Land Surveying Civil Engineering and Architecture Unit 3 – Lesson 3.4 – Site Considerations Reading the Rod Upper Stadia Reading = ft Rod Reading = ft Lower Stadia Reading = ft What measurement does the horizontal crosshair indicate? [When ready, click for answer] This means that the line of sight of the instrument is at 5.25 feet above the point on which the rod rests. You will notice that the stadia hairs can also be read. What is the upper stadia reading? (click when ready) ft When the crosshair or stadia reading fall within a whit or black zone, choose the closest edge. What is the lower stadia reading? (click when ready) ft Project Lead The Way, Inc. Copyright 2010

Stadia Readings Estimate distance between rod and instrument
Land Surveying Civil Engineering and Architecture Unit 3 – Lesson 3.4 – Site Considerations Stadia Readings Estimate distance between rod and instrument Rod intercept is the difference between stadia readings Estimated distance Stadia multiplier typically = 100 Indicated on inside of instrument case or in Instructional Manual Project Lead The Way, Inc. Copyright 2010

Stadia Readings Upper Stadia Reading = 5.30 ft
Land Surveying Civil Engineering and Architecture Unit 3 – Lesson 3.4 – Site Considerations Stadia Readings Upper Stadia Reading = ft Lower Stadia Reading = ft Rod Intercept = 0.10 ft Using the stadia readings, you can estimate the distance between the instrument and the rod. First find the rod intercept by subtracting the lower stadia reading from the upper stadia reading. Then multiply the rod intercept by the stadia multiplier (usually 100). Project Lead The Way, Inc. Copyright 2010

Stadia Reading Rod Reading = 5.06 ft Upper Stadia = 5.13 ft
Land Surveying Civil Engineering and Architecture Unit 3 – Lesson 3.4 – Site Considerations Stadia Reading Upper Stadia = 5.13 ft Let’s practice reading the rod. What is the rod reading here? (click) What is the upper stadia reading? (click) What is the lower stadia reading? (click) Estimate the distance between the instrument and the rod using the stadia readings. Rod intercept (click) Approximate distance (click) Rod Reading = 5.06 ft Lower Stadia = 4.99 ft Project Lead The Way, Inc. Copyright 2010

Read the Rod Land Surveying Civil Engineering and Architecture
Unit 3 – Lesson 3.4 – Site Considerations Read the Rod Note to teacher: Exit presentation mode. Use your mouse to drag the crosshairs over the rod to allow students to practice reading different measurements. You can also make the crosshairs larger or smaller to change the rod intercept. Project Lead The Way, Inc. Copyright 2010

Differential Leveling
Land Surveying Civil Engineering and Architecture Unit 3 – Lesson 3.4 – Site Considerations Differential Leveling The establishment of differences in elevation between two or more points with respect to a datum Instrument Point of Unknown Elevation Rod Rod If you start with a point of known elevation, such as a benchmark, you can determine the elevation of another point using differential leveling. BM Project Lead The Way, Inc. Copyright 2010

Land Surveying Civil Engineering and Architecture Unit 3 – Lesson 3.4 – Site Considerations Differential Leveling Let’s use differential leveling to determine the elevation of three points (A, B, and C) using the know elevation of a bench mark. Land surveyors record their measurements and observations in a field book. The notes include all of the measurements taken and, depending on the type of survey performed, a sketch. The record of measurements and observations are often called field notes. Reproduce this sketch of the plan view of a survey in your field notes. Elev ft Project Lead The Way, Inc. Copyright 2010

Land Surveying Civil Engineering and Architecture Unit 3 – Lesson 3.4 – Site Considerations Differential Leveling Start with point of known elevation Benchmark (BM) Point of Reference (POR) Rod reading 7.59 ft (BS) ft (HI) 7.59 ft ft Sight to rod on BM Backsight (BS) To find the elevation of an unknown point, you must start with a point of known elevation, such as a benchmark or another point of reference. (click) Here the benchmark elevation is ft. (click) The rod person places the rod on the benchmark (or POR) and the instrument person sights on the rod. (click) The rod reading is called a backsight. A backsight is always a sight back to a point of known elevation. (click) In this case the backsight reading is 7.59 ft, which means that the view through the telescope at the horizontal crosshair is at 7.59 feet above the BM elevation. (click) We call the elevation of this line-of-site the height of instrument or HI. (click) To find the HI elevation, add the backsight to the benchmark elevation. In this case, the HI is or feet. (click) This is the distance from the datum to the line of sight of the instrument. (click) [Let students copy this diagram into their notes.] Height of Instrument (HI) HI = BM elev + BS HI = = ft Project Lead The Way, Inc. Copyright 2010

Field Notes AUTO LEVEL READINGS PT (+) BS HI (-) FS ELEV
Land Surveying Civil Engineering and Architecture Unit 3 – Lesson 3.4 – Site Considerations Field Notes AUTO LEVEL READINGS STADIA PT (+) BS HI (-) FS ELEV TOP/BOT STADIA DIST /Angle BM 350.00 7.59 357.59 7.85 / 7.33 52 ft In the table on the field notes, start with the point of known elevation. Always include zeros to show the precision of the information or measurement. In this case, we know the elevation to the hundredths place. Use zeros to indicate this. Record the backsight (click). The rod is incremented to hundredths of a foot. Find the height of instrument by adding the backsight to the known elevation. (click) Note that the + in the BS column indicates that a backsight is always added to the elevation. Note that other information can also be recorded, including stadia readings, distance, and the horizontal angle between points. Let’s record the stadia readings so that we can estimate distances. (click) What is the estimated distance between the instrument and the rod using the stadia readings? (click) Project Lead The Way, Inc. Copyright 2010

Land Surveying Civil Engineering and Architecture Unit 3 – Lesson 3.4 – Site Considerations Differential Leveling Without moving the tripod, Sight to rod on point of unknown elevation Foresight (FS) Rod reading 2.36 ft (FS) 2.36 ft Elev. ft Point of Interest IMPORTANT: DO NOT MOVE THE TRIPOD AFTER YOU TAKE A BACKSIGHT UNTIL YOU HAVE TAKEN A FORESIGHT. The rod person now moves to the point of interest and places the rod on the point of unknown elevation. The instrument man sights on the rod. The rod reading is called a foresight. A foresight is always a sight to a point of unknown elevation. (click) In this case the foresight reading is 2.36 ft, which means that the view through the telescope at the horizontal crosshair is at 2.36 feet above the point of interest. (click) The elevation of the point of interest can be calculated by subtracting the foresight reading (2.36 ft) from the height of instrument ( ). In this case, the elevation of the point of interest is ft. (click) [Allow students to copy the sketch into their notes.] Identify elevation of point Elev = HI - FS Elev = – 2.36 = ft Project Lead The Way, Inc. Copyright 2010

Field Notes x AUTO LEVEL READINGS PT (+) BS HI (-) FS ELEV
Land Surveying Civil Engineering and Architecture Unit 3 – Lesson 3.4 – Site Considerations Field Notes AUTO LEVEL READINGS STADIA PT (+) BS HI (-) FS ELEV TOP/BOT STADIA DIST /Angle BM 7.59 357.59 350.00 7.85 / 7.33 52 ft x 2.36 355.23 PT- A 2.54 / 2.19 35 ft Because you know the elevation of the benchmark, you will not take a foresight to that location. Place an x in the FS column to ensure that you do not record a reading here. (click) Record the point designation for the point of interest (click). Here we will call the location Point A; however, this could be a description such as rock, building corner, top of curb, etc. Record the foresight in the Point A row (click). Now record the elevation of Point A next to the FS (click). Notice the minus in the FS column heading. A foresight is always subtracted from the HI in the row above. Record the stadia readings. (click). Estimate the distances from the instrument to point A (click). Project Lead The Way, Inc. Copyright 2010

Land Surveying Civil Engineering and Architecture Unit 3 – Lesson 3.4 – Site Considerations Differential Leveling 2.36 ft (FS) 7.59 ft (BS) In review, we started with a known elevation at the BM. We added the BS to the BM elevation to obtain the height of instrument. We then subtracted the FS to the point of interest from the HI to obtain the elevation of the new point. Project Lead The Way, Inc. Copyright 2010

Field Notes x AUTO LEVEL READINGS PT (+) BS HI (-) FS ELEV
Land Surveying Civil Engineering and Architecture Unit 3 – Lesson 3.4 – Site Considerations Field Notes AUTO LEVEL READINGS STADIA PT (+) BS HI (-) FS ELEV TOP/BOT STADIA DIST /Angle BM 7.59 357.59 350.00 7.85 / 7.33 52 ft PT-A 2.36 355.23 2.54 / 2.19 35 ft x PT- B 4.17 353.42 If additional elevations are needed at points that are clearly visible from the location of the instrument, you may leave the instrument in place and move the rod to the other points of interest. Because you are not moving the instrument, the HI will remain the same. These field notes show the progression of taking additional foresights (to points of unknown elevation) and calculating the elevations of these points. If the approximate distances are needed, don’t forget to take the stadia readings while taking the FS or BS. [As you click through the entries, allow students time to compute the elevations and approximate distances for points B and C to make sure they understand the calculation.] 4.40 / 3.93 47 ft PT-C 12.91 344.68 13.21 / 12.61 60 ft Project Lead The Way, Inc. Copyright 2010

Land Surveying Civil Engineering and Architecture Unit 3 – Lesson 3.4 – Site Considerations Image Sources Sanford, F. (2006). Seminole County geodetic control points. Seminole County, Florida: Department of Public Works. United States Geological Survey (USGS) National Oceanographic and Atmospheric Administration Photo Library Istockphoto.com Project Lead The Way, Inc. Copyright 2010

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