Transcript Land Surveying

Topographic Survey
Gathers data on the location of natural and manmade features, contours, and ground elevation
to create a topographic map
Courtesy USGS
Property Survey
(or Boundary Survey)
• Establishes property
lines for a lot
• Used to create a plat
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.
Site Survey
(Plot Survey or Lot Survey)
• Combination of a property survey and
topographic survey
• May be required to receive a construction permit
Construction Survey
Locates points and elevations that can be
used to establish correct locations and
elevations for engineering and
architectural projects
Courtesy Isle of Palms, SC Recreation Department
Optical Equipment
Requires a visual line-of-sight
©iStockphoto.com
A theodolite measures
vertical and horizontal
angles
©iStockphoto.co
m
A total station is an
electronic/optical
surveying instrument
Optical Equipment
Automatic (Auto) Level
• Commonly used on
building sites
• Internal compensator
can automatically
level the instrument
Kennedy
• Measures difference in elevation between
the line of sight and a point
Kennedy
Other Equipment
©iStockphoto.com
Professional Tape Measure
Kennedy
Kennedy
Leveling Rod
Courtesy USGS
http://gallery.usgs.gov/photos/07_22_20
09_j51Qi76Hgb_07_22_2009_13
Tripod
Kennedy
Field Book
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
Widimedia.com
Telescope
Auto Level
Sight
Mirror
Diopter
Adjustment
Ring
Bulls Eye
Level
Horizontal
Tangent
Knob
Horizontal
Angle
Rotation Ring
Eyepiece
Leveling
Screws
Kennedy
Reading the Rod
Vertical
crosshair
Stadia hairs
Horizontal
crosshair
View through the telescope
Beveled
hatch
marks
Reading the Rod
Upper Stadia Reading = 5.30 ft
Rod Reading = 5.25 ft
Lower Stadia Reading = 5.20 ft
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
Stadia Readings
Upper Stadia Reading = 5.30 ft
Lower Stadia Reading = 5.20 ft
Rod Intercept = 0.10 ft
Stadia Reading
Upper Stadia = 5.13 ft
Rod Reading = 5.06 ft
Lower Stadia = 4.99 ft
Read the Rod
Differential Leveling
The establishment of differences in
elevation between two or more points with
respect to a datum
Instrument
Rod
Rod
BM
Point of
Unknown
Elevation
Differential Leveling
Elev. 350.00 ft
Differential Leveling
• Start with point of
known elevation
• Sight to rod on BM
Backsight (BS)
• Height of Instrument (HI)
HI = BM elev + BS
HI = 350.00 + 7.59 = 357.59 ft
357.59 ft
357.59 ft (HI)
7.59 ft
Benchmark (BM)
Point of Reference
(POR)
Rod reading
7.59 ft (BS)
Field Notes
AUTO LEVEL READINGS
STADIA
PT
BM
(+)
BS
HI
7.59
357.59
(-)
FS
ELEV
TOP/BOT
STADIA
DIST
/Angle
350.00
7.85 / 7.33
52 ft
Without moving the
tripod,
• Sight to rod on point
of unknown
elevation
Foresight (FS)
Rod reading
2.36 ft (FS)
• Identify elevation of
point
Elev = HI - FS
Elev = 357.59 – 2.36 = 355.23 ft
2.36 ft
Differential Leveling
Elev.
355.23 ft
Point of Interest
Field Notes
AUTO LEVEL READINGS
STADIA
PT
BM
PT- A
(+)
BS
7.59
HI
(-)
FS
ELEV
TOP/BOT
STADIA
DIST
/Angle
357.59
x
350.00
7.85 / 7.33
52 ft
2.36
355.23
2.54 / 2.19
35 ft
Differential Leveling
2.36 ft (FS)
7.59 ft (BS)
Field Notes
AUTO LEVEL READINGS
STADIA
PT
BM
(+)
BS
7.59
HI
(-)
FS
357.59
x
ELEV
TOP/BOT
STADIA
DIST
/Angle
350.00
7.85 / 7.33
52 ft
35 ft
PT-A
2.36
355.23
2.54 / 2.19
PT- B
4.17
353.42
4.40 / 3.93
47 ft
PT-C
12.91
344.68
13.21 / 12.61
60 ft