Construction Surveys. List of Figures Readings: Chapter 23 Readings: Chapter 23 Figures used: Figures used: –23-1 to 23-10. Material to be considered:

Construction SurveysConstruction Surveys

List of FiguresList of Figures

• Readings: Chapter 23Readings: Chapter 23• Figures used:Figures used:

– 23-1 to 23-10.23-1 to 23-10.

Material to be considered: 23-7.Material to be considered: 23-7.

Stages and Measurements of CSStages and Measurements of CS• Design stages: topographic Surveying, and site mapsDesign stages: topographic Surveying, and site maps• Construction stage: Construction stage:

• Setting-out and positioning works. 60% of surveying hours. Setting-out and positioning works. 60% of surveying hours. • involves establishing lines and grades by means of stakes involves establishing lines and grades by means of stakes

and string lines to guide the contractorand string lines to guide the contractor• During and after construction: as built drawings, a record and During and after construction: as built drawings, a record and

a check.a check.• Measurements involved: Horizontal and vertical angles, Measurements involved: Horizontal and vertical angles,

elevations, horizontal distances. elevations, horizontal distances.

CS EquipmentCS Equipment• Laser Instruments:Laser Instruments:

– to create a visible line, or plane of known elevation or tiltto create a visible line, or plane of known elevation or tilt– The line or plane could be horizontal, vertical, or tilted.The line or plane could be horizontal, vertical, or tilted.– Single beam lasers will project visible string lines or Single beam lasers will project visible string lines or

plumb linesplumb lines– Rotating beam lasers: a rotating single beam to create a Rotating beam lasers: a rotating single beam to create a

plane.plane.– Examples: Examples:

» Laser levels, laser theodolite and total stations, hand-Laser levels, laser theodolite and total stations, hand-held EDM instruments (Figures 23-1 to 23-4)held EDM instruments (Figures 23-1 to 23-4)

» Recent technology of prism-less total stations and Recent technology of prism-less total stations and EDMs, and HDS “High Density Surveys”.EDMs, and HDS “High Density Surveys”.

» Machine GuidanceMachine Guidance

Laser is used to guide the blade

HDS Surveys

•Total Stations: the ones designed for CS are Total Stations: the ones designed for CS are of lower angular resolution(10” or 20”), and of lower angular resolution(10” or 20”), and shorter ranges(500 m)shorter ranges(500 m)

•Relative GPS: sub-centimeter accuracy with Relative GPS: sub-centimeter accuracy with real time kinematic GPS in horizontal, few real time kinematic GPS in horizontal, few cm in vertical. Must maintain visibility with cm in vertical. Must maintain visibility with satellitessatellites

•LevelsLevels

Horizontal and Vertical ControlHorizontal and Vertical Control

• Before Construction: new control points around the site must be Before Construction: new control points around the site must be established with high accuracy. Additional points inside the site established with high accuracy. Additional points inside the site are then established. All points must be “tied out” for are then established. All points must be “tied out” for repositioning. These initial points should:repositioning. These initial points should:• Meet certain accuracy standardsMeet certain accuracy standards• Be clearly marked, referenced, and recordedBe clearly marked, referenced, and recorded• Be far enough to be safe during construction.Be far enough to be safe during construction.

• During Construction: additional control is extended by the During Construction: additional control is extended by the contractor as needed, around or inside the structure. These contractor as needed, around or inside the structure. These additional points should be close enough to the structure so that additional points should be close enough to the structure so that workers with simple equipment can use themworkers with simple equipment can use them

Staking out a PipelineStaking out a Pipeline• Sanitary (sewage) sewers and storm sewers which Sanitary (sewage) sewers and storm sewers which

carry storm runoffs operate under gravity. The carry storm runoffs operate under gravity. The grade in such pipelines is critical. City water, oil, grade in such pipelines is critical. City water, oil, and natural gas pipes are not as critical.and natural gas pipes are not as critical.

• The location of the line is determined after a The location of the line is determined after a profile leveling is done. profile leveling is done.

• The center line and an offset reference line are The center line and an offset reference line are established.established.

• Precise alignment and grade are guided by laser Precise alignment and grade are guided by laser beams or battered boards.beams or battered boards.

Pipe Laying Laser system by Apache

Source: laserlevels.net

Staking Pipeline GradesStaking Pipeline Grades• A- Cut and Fill: A- Cut and Fill:

• The center line and an offset line are marked and stationed. The center line and an offset line are marked and stationed. The actual profiling and staking are on the offset line, not the The actual profiling and staking are on the offset line, not the CL.CL.

• Using profile leveling method, obtain ground elevation at Using profile leveling method, obtain ground elevation at each stake, compute the depth of cut or fill to the invert level. 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 Mark that depth on the stake side facing the trench, mark the station on the other side of the stake.station on the other side of the stake.

• B- Line and grade: B- Line and grade: • Generally done using laser equipment. Generally done using laser equipment.

Staking out a BuildingStaking out a Building• First step is to locate the building by boundary surveying. First step is to locate the building by boundary surveying.

Stakes are placed temporarily at the corners as a check.Stakes are placed temporarily at the corners as a check.• In a small size building, a set of batter boards and reference In a small size building, a set of batter boards and reference

stakes are first set. The boards are around the building stakes are first set. The boards are around the building corners and nailed at a full number of feet above the corners and nailed at a full number of feet above the footing base or at first floor elevation.footing base or at first floor elevation.

• Nails are driven into the batter board tops so that a string Nails are driven into the batter board tops so that a string connecting them will define an outside wallconnecting them will define an outside wall

• See fig 23-7, and the example which illustrates staking out See fig 23-7, and the example which illustrates staking out the building in fig 23-8.the building in fig 23-8.

• In a larger building, radial methods, the one you used to In a larger building, radial methods, the one you used to lay out piles, are used used. Fig 23-9lay out piles, are used used. Fig 23-9

Additional Control for BuildingsAdditional Control for Buildings• Elevations: Elevations:

Visible benchmark(s) should be set. Additional control could be done Visible benchmark(s) should be set. Additional control could be done using marks on nearby buildings, or marks on interior structure using marks on nearby buildings, or marks on interior structure elements (columns, walls).elements (columns, walls).

• HorizontalHorizontal: : temporary batter boards inside the site, marks on nearby buildings.temporary batter boards inside the site, marks on nearby buildings.

• Plumbness:Plumbness: • Essential for multistory buildings: columns, elevator shafts, construction walls, Essential for multistory buildings: columns, elevator shafts, construction walls,

etc.etc.• Checked by a theodolite line of sight rotating in a vertical plane, or by lasers.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 Two instruments, with perpendicular line of sights, could be used to guide the

construction of vertical members in real time. construction of vertical members in real time.

CS Using Total StationsCS Using Total Stations• We are simply trying to define (X,Y) and maybe (Z) of the center of the 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.TS. Once stored in memory, the TS can do further computations onsite.• Horizontal OrientationHorizontal Orientation: :

• By azimuth: input occupied point coordinates and azimuth to another point.By azimuth: input occupied point coordinates and azimuth to another point.• By coordinates: input occupied point coordinates and another point coordinatesBy coordinates: input occupied point coordinates and another point coordinates• By resection: input coordinates of unoccupied points , at least three, output is By resection: input coordinates of unoccupied points , at least three, output is

occupied point coordinates.occupied point coordinates.• Vertical Orientation: if necessary, output is HI:Vertical Orientation: if necessary, output is HI:

• By adding the instrument height to occupied point elevation.By adding the instrument height to occupied point elevation.• By adding the vertical distance to a benchmark elevation and prism height: By adding the vertical distance to a benchmark elevation and prism height:

HI = elevHI = elevBB + h + hpp - V - V

Staking out with a Total StationStaking out with a Total Station• First the instrument is oriented, and a file that First the instrument is oriented, and a file that

contains control points and stake points contains control points and stake points information is downloaded into the total station.information is downloaded into the total station.

• For 2-D stakeout, the number of the desired stake For 2-D stakeout, the number of the desired stake point is entered, the instrument will display point is entered, the instrument will display differences of angles and distances to orient the differences of angles and distances to orient the prism.prism.

• For 3-D works, The difference in elevation For 3-D works, The difference in elevation between the stake elevation and the required between the stake elevation and the required elevation (cut or fill) is also displayed.elevation (cut or fill) is also displayed.