1. 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
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2. 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.
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3. LEGAL DESCRIPTION Metes and Bounds
They designate the boundaries of land parcels by describing lengths and directions of lines from a point of beginning (POB) or monument.
Lines are described with respect to natural or artificial monuments and baselines.
Line length is measured along a level plane.
Directions are bearing angles with respect to the previous line.

4. 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.
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5. 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
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6. 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
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7. 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
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8. 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
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9. 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
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10. 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
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11. 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
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12. 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
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13. 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
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14. 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).
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15. 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
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16. 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.
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17. 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
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18. Differential Leveling
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
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19. Differential Leveling
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
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20. 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)
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21. Differential Leveling
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
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22. 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).
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23. Differential Leveling
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.
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24. 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
4.40 / 3.93
47 ft
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.]
PT-C
12.91
344.68
13.21 / 12.61
60 ft
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