Construction Surveys

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Construction Surveys
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List of Figures

• Readings Chapter 23
• Figures used
• 23-1 to 23-10.
• Material to be considered 23-7.

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Stages and Measurements of CS

• Design stages topographic Surveying, and site
  maps
• Construction stage
• Setting-out and positioning works. 60 of
  surveying hours.
• involves establishing lines and grades by means
  of stakes and string lines to guide the
  contractor
• During and after construction as built drawings,
  a record and a check.
• Measurements involved Horizontal and vertical
  angles, elevations, horizontal distances.

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CS Equipment

• Laser Instruments
• to create a visible line, or plane of known
  elevation or tilt
• The line or plane could be horizontal, vertical,
  or tilted.
• Single beam lasers will project visible string
  lines or plumb lines
• Rotating beam lasers a rotating single beam to
  create a plane.
• Examples
• Laser levels, laser theodolite and total
  stations, hand-held EDM instruments (Figures 23-1
  to 23-4)
• Recent technology of prism-less total stations
  and EDMs, and HDS High Density Surveys.
• Machine Guidance

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Laser is used to guide the blade
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HDS Surveys
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• Total Stations the ones designed for CS are of
  lower angular resolution(10 or 20), and shorter
  ranges(500 m)
• Relative GPS sub-centimeter accuracy with real
  time kinematic GPS in horizontal, few cm in
  vertical. Must maintain visibility with
  satellites
• Levels

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Horizontal and Vertical Control

• Before Construction new control points around
  the site must be established with high accuracy.
  Additional points inside the site are then
  established. All points must be tied out for
  repositioning. These initial points should
• Meet certain accuracy standards
• Be clearly marked, referenced, and recorded
• Be far enough to be safe during construction.
• During Construction additional control is
  extended by the contractor as needed, around or
  inside the structure. These additional points
  should be close enough to the structure so that
  workers with simple equipment can use them

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Staking out a Pipeline

• Sanitary (sewage) sewers and storm sewers which
  carry storm runoffs operate under gravity. The
  grade in such pipelines is critical. City water,
  oil, and natural gas pipes are not as critical.
• The location of the line is determined after a
  profile leveling is done.
• The center line and an offset reference line are
  established.
• Precise alignment and grade are guided by laser
  beams or battered boards.

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Pipe Laying Laser system by Apache
Source laserlevels.net
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Staking Pipeline Grades

• A- Cut and Fill
• The center line and an offset line are marked and
  stationed. The actual profiling and staking are
  on the offset line, not the CL.
• Using profile leveling method, obtain ground
  elevation at each stake, compute the depth of cut
  or fill to the invert level.
• Mark that depth on the stake side facing the
  trench, mark the station on the other side of the
  stake.
• B- Line and grade
• Generally done using laser equipment.

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Staking out a Building

• First step is to locate the building by boundary
  surveying. Stakes are placed temporarily at the
  corners as a check.
• In a small size building, a set of batter boards
  and reference stakes are first set. The boards
  are around the building corners and nailed at a
  full number of feet above the footing base or at
  first floor elevation.
• Nails are driven into the batter board tops so
  that a string connecting them will define an
  outside wall
• See fig 23-7, and the example which illustrates
  staking out the building in fig 23-8.
• In a larger building, radial methods, the one you
  used to lay out piles, are used used. Fig 23-9

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Additional Control for Buildings

• Elevations
• Visible benchmark(s) should be set. Additional
  control could be done using marks on nearby
  buildings, or marks on interior structure
  elements (columns, walls).
• Horizontal
• temporary batter boards inside the site, marks on
  nearby buildings.
• Plumbness
• Essential for multistory buildings columns,
  elevator shafts, construction walls, etc.
• Checked by a theodolite line of sight rotating in
  a vertical plane, or by lasers.
• Two instruments, with perpendicular line of
  sights, could be used to guide the construction
  of vertical members in real time.

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CS Using Total Stations

• We are simply trying to define (X,Y) and maybe
  (Z) of the center of the TS. Once stored in
  memory, the TS can do further computations
  onsite.
• Horizontal Orientation
• By azimuth input occupied point coordinates and
  azimuth to another point.
• By coordinates input occupied point coordinates
  and another point coordinates
• By resection input coordinates of unoccupied
  points , at least three, output is occupied point
  coordinates.
• Vertical Orientation if necessary, output is HI
• By adding the instrument height to occupied point
  elevation.
• By adding the vertical distance to a benchmark
  elevation and prism height
• HI elevB hp - V

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Staking out with a Total Station

• First the instrument is oriented, and a file that
  contains control points and stake points
  information is downloaded into the total
  station.
• For 2-D stakeout, the number of the desired stake
  point is entered, the instrument will display
  differences of angles and distances to orient the
  prism.
• For 3-D works, The difference in elevation
  between the stake elevation and the required
  elevation (cut or fill) is also displayed.