Benchmark Establishment GTS Secondary Tertiary is an important topic for surveyors and engineers who work with control networks. In this guide I explain how to set and keep permanent control points using clear steps. The focus is on practical procedure, permanent benchmark methodology, and the GTS secondary tertiary benchmark setting procedure.
Why Benchmarks and Control Points Matter
Benchmarks are fixed points with known coordinates and elevations. They help keep measurements accurate over time. This section gives a short view of why we need them and how they fit into the GTS system.
What is a benchmark?
A benchmark is a physical marker or point with a known position. It can be primary, secondary, or tertiary in the control hierarchy. A permanent control point is meant to last many years.
Levels of control
- Primary benchmarks: highest accuracy and usually set by national agencies.
- Secondary benchmarks: support local networks and tie to primary benchmarks.
- Tertiary benchmarks: used for local projects and short-term surveys.
Planning Benchmark Establishment
Good planning reduces errors. Use a clear checklist and follow the permanent benchmark methodology. This helps when you set a benchmark that must stand for long time.
Site selection
Choose a stable, accessible site. Avoid places prone to flooding, construction, or movement. A good site makes the permanent control point useful for years.
Permissions and records
Get permission from land owners or agencies. Record site details and legal notes before you set any permanent benchmark.
Equipment and Materials
Use reliable instruments and long-lasting materials. The right tools make the GTS secondary tertiary benchmark setting procedure easier and safer.
Common tools
- Total station or GNSS receiver
- Tripod, prism, or antenna mount
- Concrete, metal benchmark plates, or deep-driven pins
- Survey record book or digital logging device
Marking a permanent control point
Use corrosion-resistant markers such as brass plates or stainless steel pins. Protect the marker with concrete or stable housing to prevent damage.
GTS Secondary and Tertiary Benchmark Setting Procedure
Below is a clear, step-by-step description of the GTS secondary tertiary benchmark setting procedure. Follow each step and keep good records.
Step 1: Reference and ties
Identify nearby primary or known secondary benchmarks. Measure ties to at least two stable points. This links the new point to the larger network.
Step 2: Precise measurement
Use GNSS or total station to measure coordinates and elevation. Take multiple readings at different times if possible. Average results for better accuracy.
Step 3: Install permanent marker
Install a durable marker. Embed it in concrete or use a deep-driven metal pin. Ensure the marker is flush and protected from surface wear.
Step 4: Record and publish
Document coordinates, method, instruments, and environmental notes. Publish the data to local or national databases when required.
Permanence and Maintenance
Permanent benchmarks need care. A maintenance plan keeps control points reliable and useful for future surveys.
Inspection schedule
- Inspect after major weather events.
- Check every 3–5 years for local use, more often for critical sites.
- Repair or re-establish markers if they show damage or drift.
Documentation updates
Update logs when you inspect or remeasure. Note any changes in surrounding features that may affect the point.
Permanent Benchmark Methodology
The permanent benchmark methodology covers how to create a long-term reference with reliability and traceability. It balances practical field work and strong record-keeping.
Key principles
- Redundancy: measure ties to multiple known points.
- Durability: use materials built to last.
- Traceability: keep complete records of methods and instruments.
Survey accuracy levels
Decide accuracy targets before you start. Secondary benchmarks typically need higher accuracy than tertiary ones. Follow local standards for tolerance values.
Comparison Table: Benchmark Types
| Type | Use | Longevity |
| Primary | National reference and highest accuracy | Very long |
| Secondary | Regional networks, links to primary | Long |
| Tertiary | Local projects, less strict accuracy | Variable |
| Permanent control point | Long-term site-specific reference | Long to very long |
Best Practices and Common Mistakes
Follow best practices to avoid rework. These tips reflect lessons from many projects.
Best practices
- Use stable monuments and good materials.
- Cross-check measurements with other control points.
- Keep clear, legible records and digital backups.
Common mistakes
- Placing markers in unstable ground.
- Poor ties to other benchmarks.
- Skipping permissions and legal checks.
Frequently Asked Questions
What is the difference between secondary and tertiary benchmarks?
Secondary benchmarks link to primary networks and require higher accuracy. Tertiary benchmarks serve local projects and can tolerate lower precision.
How do I make a control point permanent?
Use durable markers, protect them with concrete or housing, record all measurements, and register the point with the appropriate authority if needed.
Conclusion
Benchmark establishment for GTS secondary and tertiary control points follows clear steps: plan, measure, install durable markers, and document. Use the permanent benchmark methodology to keep points reliable. Good practice saves time and keeps survey data trusted for years.
