Accurate and robust control networks are the precursor to detailed construction surveys and setting out activities. This is achieved through expertly installed control stations that provide stable spatial reference points.
These networks minimise errors, data discrepancies, and help prevent costly rework in every measurement, stakeout, and design element.
A well-established control network delivers positional certainty across the entire site, allowing multiple teams to work in harmony and ensuring that phased works tie together seamlessly.
By referencing all works to either Local Grid or the nationally recognised Ordnance Survey (OS) Grid systems, the project is grounded in a geospatial framework that guarantees compatibility with statutory requirements, mapping, and future maintenance or expansion.
What Control Networks Help With
You can use control networks to measure points in a horizontal or vertical plane, depending on the needs of your project. It’s also possible to establish ‘secondary’ controls at a later date to adjust surveying at different stages of construction.
Control network surveying can be used to record:
Grid lines
Walls
Benchmarks
Building elements
Structural alignment
Best Practice for Installing Control Networks
A control network will only supply reliable and accurate data when it has been installed according to industry best practice. Effective control networks must be:
Positioned Strategically: Stations must form intervisible geometric frameworks that cover your working area. The set of control network points must be positioned to maintain network integrity and reduce distortion risk, even as projects evolve.
Marked Securely: Durable ground markers (such as stainless-steel bolts, concrete monuments, or survey nails) are installed at each station location. These are often referenced by nearby witness marks or clearly documented site diagrams to prevent accidental disturbance or loss.
Precisely Coordinated: Primary control positions should be established using high-precision GNSS receivers operating in conjunction with leading total stations. Stations can also be tied into the Ordnance Survey National Grid or a Local Grid to align the entire project with broader spatial datasets.
Verified Regularly: Ongoing control network checks using control traverses, redundant observations, and least squares adjustment techniques safeguard against movement or error, with audit trails maintained for full transparency.
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We have a long-standing relationship with SEP Engineers, who continue to provide us with Site Engineer’s that fully meet our contract setting-out requirements, ensuring high standards of quality are continually met.
Gerry McCoy, Operations Director, Bethell Group
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Over the past 7 years we have received high-level, professional, and reliable Site Engineering support from SEP Engineers on most of our contracts in the NW. Their expertise and commitment have consistently exceeded expectations. I highly recommend them for any Site Engineering needs.
Anthony Judge, Regional Managing Director, GMI Construction Plc
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SEP Engineers have consistently supplied quality Site Engineers for varied range of activities over many, many years. This working relationship has developed over 20 plus years and continues to grow.
Alex Keyes, Construction Director, Murraywood Construction
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Unlike a recruitment agency, SEP Engineers employ, train, and support their own Engineers as well as having a well-established network of Subcontractors, bringing a wealth of experience in sourcing the right expertise for our Civil Engineering and Earthworks projects.
Dan Wilkinson, Technical Director, D Morgan Plc
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Their commitment in sourcing and providing the best Engineering staff in the NW sets the apart from their competitors and I know we can call upon them at very short notice to supply whatever we need. I couldn’t recommend them highly enough.
Chris Gallagher, Managing Director, Vermont Construction
State-of-the-Art Equipment
Modern control networks rely on a suite of survey equipment to record measurements and integrate with wider surveying workflows. Common instruments include:
Total Stations: For angular and distance measurements with unmatched precision, essential for traverses and recording horizontal and vertical data.
GNSS Receivers: To rapidly establish coordinates referenced to the OS National Grid or other geodetic frameworks, and to provide absolute positioning accuracy across large or even remote sites.
Digital Levels: For establishing precise elevation benchmarks, particularly in projects requiring high vertical accuracy.
Data Collectors and Software: For seamless data capture, real-time adjustment, and integration with CAD and GIS platforms.
Whether referencing the site to a Local Grid (tailored for project-specific requirements) or fully integrating the survey into the Ordnance Survey National Grid for maximum compatibility, a dependable control network is essential. It will cover your construction project for quality assurance, legal compliance, and long-term success.
What is Ordnance Datum?
Ordnance Datum (OD) is used to measure heights throughout England by referencing mean sea level. Surveyors and setting out engineers may use an OD to derive altitudes during an ordnance survey. In England, the ‘zero’ height level is based on the sea level in Newlyn in Cornwall, which is why you can sometimes see it written as Ordnance Datum Newlyn (ODN).
Accurate and Compliant Deliverables
All the work we complete, including control network installation, is thoroughly catalogued so you can see exactly how the network has been established, the equipment used, safety precautions, and the measurements taken. Our team is experienced in achieving millimetre accuracy through control networks, setting your project up for success.
You also have unfettered access to control network set-up methodology and operational data, which is ideal for client handovers. They’ll be safe knowing that we take every step necessary to maintain compliance.
Why Choose SEP Engineers?
Experienced Professionals: All Engineers hold CSCS/SMSTS certifications and have a minimum of 5 years’ site experience.
Proven Capability: Site-vetted for high-risk environments including rail, nuclear, and airport projects.
Advanced Technology: Industry-leading robotic and GNSS systems for precise, efficient delivery.
Quality Assurance: Real-time data verification by our Training & Quality Manager and Technical Support Department, ensuring each dataset is validated before use.
Auditable Deliverables: Every setting-out operation is logged, photographed, and archived to support client QA and compliance processes.
When precision matters, SEP Engineers provide the certainty your project deserves.
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