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Chase Farm


Construction Verification & As-Built Surveys

Survey Methodology & Project Delivery

Robotic Total Station & GNSS.

Chase Farm Hospital
As-Built Surveys

Construction Verification

  • As-Built Surveys
  • Construction Verification Reports

Sector: Construction & Engineering

About This Project

SurveyWorx were commissioned to manage & deliver Construction Verification As-Built Surveys across 5 Floors/Levels, working in collaboration with the Construction & Design Teams who would lead the Construction/Development of the Project.

Deliverables/Outputs would highlight deviations between the As-Built Constructed Position & Design.

Accurate Survey Data/Drawings would provide Project Managers & Design Teams with vital information in relation to the As-Built accuracy of constructed elements when compared against Design Drawings.


As-Built Survey Specifications

  • Establish/Verify Control Network
  • Slab Level Verification (+/- SSL)
  • Slab Edge Position
  • Columns – Position & Verticality
  • Slab Openings/Penetrations
  • Structural Beams Position & Level
  • Lift Shaft Position & Verticality

Survey Methodology & Project Delivery

Using a combination of Robotic Total Stations, GNSS, HD Laser Scanning Technology & “Robust Survey Methods” to capture & verify accurate Survey Data, the Survey Specification was delivered both efficiently & cost effectively within the allocated timescales.

As-Built Survey Data was captured/acquired using Total Stations (1”) & Leica P40 HD Laser Scanners.

Establish Control Network

Primary Control Network & Grid System was Verified/Checked using a combination of Total Station (1”), Zenith/Vertical Laser Plummet, Steel Tape & Leica Precise Digital Level (DNA03).

Total Station Data Post-Processing

Raw Survey Data/Observations were Post-Processed through SCC Survey Software. Data was captured & coded using a specific Project Code List written within SCC. This ensured all features were assigned a specific Code when Surveyed & imported to a defined Layering System within SCC. Data was then exported to AutoCAD for final editing.

HD Scan Data Post-Processing

HD Scan Data was Post-Processed to produce a fully Registered/Coordinated Point Cloud, using Leica Cyclone Software. Point Cloud Data was referenced to the Site Control Network using Secondary Primary Control transferred vertically through the Buildings/Structures. Post-Processing/Registration was completed using a combination of Target-Based Registration & Cloud-to-Cloud Registration.

Quality Assurance procedures were completed with a Point Cloud Registration Report exported to highlight registration accuracy. Registration was a success with an average error of +/-2mm between individual Point Clouds.

The Point Cloud was Verified/Checked by taking sample Cross Sections/Slices through the data in order to check for any discrepancies between individual Point Cloud alignments. Point Cloud Data from the Internals was also Verified/Checked against the External Data to confirm successful Registration.

Coordinate Reference System

Survey Data related to the OS Network OSGB36(15).

Delivery & Output

Structural Design Drawings were Scaled/Transformed to Site Grid System using Grid Intersection Coordinates as references. Survey Data was imported & Drawings were completed to highlight deviations (+/- SSL) between As-Built Survey Data ‘True Position’ & Structural Design Data.

Drawings were delivered in defined categories to aid Design Teams by providing accurate & concise information while avoiding cluttered/crowded Drawings. 1) Vertical Elements; Columns, Walls & Cores. 2) Structural Slab Levels; Floor/Slab Flatness. 3) Structural Openings & Formed Edges; Slab Edge; Openings/Penetrations & Balcony Bracket Halfen Channels.

The final Drawing Package included; As-Built Survey Drawings & Control Network Reports. All Drawings were passed through Quality Assurance prior to final delivery.

The completed Surveys were delivered as a digital version in 2D AutoCAD & PDF formats.


GNSS = Global Navigation Satellite Systems.
RTK = Real Time Kinematic.
GPS = Global Positioning System.
OSGB36 = Ordnance Survey National Grid Reference System.
ETRS89 = European Terrestrial Reference System.
WGS84 = World Geodetic System (GPS/GNSS).

Sample Delivery/Output

Chase Farm Hospital
Chase Farm Hospital