Civil Engineering Surveying

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Civil Engineering Surveying
Prepaid by 140670106083 140670106002
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Planning A Survey

• Planning requires a well rounded understanding of
  surveying practices
• Process
• Choice of accuracy required (depends on use to be
  made)
• Basic Control
• Topographic
• Photogrammetry

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Planning A Survey

• Existing Control
• Search records for existing control in area
• Illinois Geological Survey Urbana, IL
• National Geodetic Survey Rolla, MO or
  Rockville, Maryland
• Reconnaissance
• Search Procedure
• Description often dated
• Can use GPS receiver (Lat. And Long)
• Probe, detectors often problems - brass

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Planning A Survey

• Choice of Instruments and Methods
• Depends on availability, location, existing
  features, and accuracy
• Computation and Drafting

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Accuracy and Errors

• Accuracy depends on
• Precise instruments
• Precise Methods
• Good Planning
• Example Angle turned with theodolite, pointed
  with care readings checked thus good precision.
  Angles of 2-3 expected, real results angles
  15 accuracy

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Errors

• 3 Types
• Blunders
• Systematic Error
• Accidental Error
• Blunder is a mistake, to help eliminate
• Every value to be recorded must be checked by
  some independent field observation

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Errors

1. Once check indicates that there is no blunder,
   field record must never be changed or destroyed
2. An overall check must be applied to every control
   survey. Make as many overall checks as possible.

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Errors

• Systematic Error an error that under the same
  conditions will always be of same size and sign.
• Basic Rules to Eliminate
• All surveying equipment must be designed and used
  so that whenever possible systematic errors will
  be eliminated automatically
• Systematic error which can not be eliminated must
  be evaluated and their relationship to conditions
  that cause them must be determined.
• Example Temperature Corrections

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Errors

• Accidental Errors (random errors) represent the
  limit of precision in the determination of a
  value
• Corrected be laws of probability
• Compass Rule and Least Squares

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Hydrographic Surveys

• Surveys and mapping of bodies of water and
  shorelines
• Rivers and Lakes Process different
• Rivers
• Normal process is to establish 2 parallel lines
  of control points on opposite sides
• River Portion 2 processes
• EDM similar to radial
• Dual instrument with position by angle and
  intersection
• Lakes
• Normal process same as river but generally do not
  have current problems

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Overall Process

1. Establish control points both horizontal and
   vertical
2. Preplan where sections are to be taken (this is
   basis for control points on shore)
3. Cross sections taken
4. If EDM, radials taken from control points due to
   difficulty in obtaining shots under 300
5. May have to combine cross sections and radial
   location to pick up anomalies not covered by
   cross sections

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Gauging Stations

• Purpose is to install either manually read or
  automatic gauges to determine stream, river,
  lake, or ocean elevations
• Process
• Establish system of BMs throughout area gauges
  will be installed
• Establish elevation mark at site for installation
• After gauges are installed, check elevation of
  each

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Topographic Surveys

• 6 Basic Methods
• Radial
• Plus/Offset
• Plus Offset
• Establish baseline (Often centerline), establish
  points at station interval 50, 100, 200
• Tie planimetric data by distance down line plus
  distance right or left (looking up stationing)
• Establish elevations on station points then
  elevation out a predetermined distance with shots
  at breaks

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Topographic Surveys

• Due additional section to locate features in
  between stations
• Equipment Tape, Level, Rod, Transit, - Right
  Angle Prism?
• Grid Method
• Take cross Section Groups and Combine
• Establish Grid baseline often property line
• Establish Perpendicular line
• Both Marked at grid interval (25, 50)
• Planimetric tied plus/offset in each grid
• Grid laid out by double taping
• Field notes 1 2 grids/page

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Topographic Surveys

• Photogrammetry
• Limitations
• Trees Leaves off no large growths of
  coniferous
• Ground Cover grass, thick weeds and vines, snow
• Clear Sky
• Tall Buildings
• Due to these Limitations Illinois only has on the
  average of 2 weeks flying time

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Topographic Surveys

• Scale Photo
• S (f/H)
• Coordinates From Photos
• XA (xa/f)(H-ha)
• YA (ya/f)(H-ha)
• Height of an object
• r radial dist. to top
• d radial dist. to top radial dist. to bottom
• h d (H) / r

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Topographic Surveys

• GPS Total Station System
• Basic of GPS
• Topo with GPS
• Topo Trimble Total Station (RTK)
• Limitations
• Must be able to maintain satellite signal
  Trees, Building
• Signal Reflection (Multipath) Buildings,
  Fences, Roofs
• Debate over elevation (0.15 /- my belief)

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Topographic Surveys

• Trace Contour
• Used to identify several contours around an area
• Plane Table Surveys
• Rarely used
• Method prepares a manuscript map in the field

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Mapping and Map Drafting

• 2 Basic Types of Maps used in Engineering
• Line Drawing
• Photogrametrically prepared manuscript or
  orthophoto map

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Mapping and Map Drafting

• Datum in Mapping
• Datum used to correlate measurements, to
  determine elevations and horizontal positions for
  points at different locations
• Topographic Maps using Symbols Show
• Spatial configuration of Earths surface
  (contours)
• Natural Features (Lakes, Rivers, etc.)
• Physical Changes caused by man

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Mapping and Map Drafting

• Planning Maps
• Used in planning Engineering work or overall
  planning at the urban, Regional, or National
  Levels
• Plotting Contours
• Interpolation
• Estimation
• Computation

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Mapping and Map Drafting

• Contours
• Characteristics of Contours
• Horizontal distance between contour lines is
  inversely proportionate to the slope
• Uniform slopes have contours evenly spaced
• Along plane surfaces (manmade) contour lines are
  straight and parallel
• Contour lines are perpendicular to lines of
  steepest slope
• All contours close upon themselves
• Different contours do not merge or cross one
  another (except vertical walls, overhangs,
  cliffs) on map

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Mapping and Map Drafting

• Factors that influence choice of map scale
• Clarity with which features can be shown
• Cost (larger scale higher cost)
• Correlation of Map data with related maps
• Desired size of map sheet
• Physical factors (number and character), nature
  of terrain, required contour interval

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Mapping and Map Drafting

• Map Classifications
• Based on American Society of Civil Engineering,
  Surveying, and Mapping Division
• Design Maps
• Used to design and construct
• Information shown on Maps

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Mapping and Map Drafting

1. The following should be on a map
2. Direction of Meridian (North)
3. Graphical Scale (Bar in case of reduction)
4. Legend or key of symbols
5. Title Block (identifiers)
6. Contour Interval
7. Datum to which both Horizontal and Vertical are
   Referenced
8. If coordinate base used what system

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Mapping and Map Drafting

• If map is to become public record (subdivision).
  It must contain in addition to the above
• Length of each line
• Direction of each line (bearing or angles)
• Subdivision numbering system (lot and block)
• Location and Kind of monuments
• Names of property owners (on site and adjacent)
• Full description of Boundary
• Certificate of Surveyor that map is correct

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Planning and Estimating from Topo Maps

• Purpose of Topo maps
• Profiles
• Grade contour
• Drainage Area
• Limits determined by following characteristics
• Begins and ends at the point in the stream to
  which it applies
• Passes through every saddle that divides drainage
  area
• Often follows ridges
• Reservoir Capacity