Underground Cabling, Duct Surveying & A55 Blockage Reporting (UK)
Openreach PIA + NRSWA accredited. ISO 9001, 14001 & 45001 certified.
30+ years’ telecom infrastructure experience.
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TNS Comms delivers underground cabling services, chamber and duct surveys, test rodding and roping (TRR), desilting, and A55 blockage reporting to keep fibre rollout programmes moving. We help you reduce failed installs, pinpoint obstructions accurately and hand over survey data in clear, client-ready formats including GIS outputs.
Openreach PIA & NRSWA Accredited Underground Cabling Contractor
TNS Comms provides professional underground duct surveying and underground cabling across the UK telecoms sector. With over 30 years of experience, our teams support major fibre network builds with safe, compliant delivery and structured documentation.
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We are:
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Openreach PIA accredited for working within Physical Infrastructure Access frameworks
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NRSWA accredited for operating safely on the public highway and street works environments
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Certified to UKAS ISO 9001 (Quality), ISO 14001 (Environment) and ISO 45001 (Health & Safety)
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These accreditations help clients reduce risk, improve programme certainty, and maintain audit-ready compliance.
We support underground infrastructure programmes for clients including:
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Our experience across Tier 1 and alternative networks means we understand the standards, reporting and operational discipline required to deliver consistently at scale.
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OFNL
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VX Fibre
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Freedom Fibre
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Airband.
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Openreach
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CityFibre
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Lightspeed Networks
Why We Survey Underground Ducts Before Cabling
Surveying underground ducts is essential because duct networks change over time and issues are often hidden until installation is attempted. Duct routes can become impacted by water ingress, collapse, third-party civils, deformation, root intrusion or general ageing.
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A professional underground duct survey helps you:
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Confirm duct and chamber condition before build
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Validate continuity between chambers
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Identify silted or obstructed sections early
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Reduce failed cable blows and aborted installs
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Plan civils accurately and avoid unnecessary excavation
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Improve design accuracy and build sequencing​
In short, surveying prevents avoidable delays and ensures ducts are ready for fibre optic installation, sub duct installation and cable blowing.
Chamber & Underground Duct Surveying Services
Chamber surveys and duct condition assessments
Our survey teams carry out:
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Chamber inspections (structure, accessibility, safety and condition)
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Duct entry/exit identification and mapping
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Route validation between chambers
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Defect logging, photos and notes captured digitally
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Asset referencing and client-ready reporting
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We capture data electronically and quality check outputs under our ISO 9001 Quality Management System.
Test Rodding & Roping (TRR) – Why It Matters
Test Rodding & Roping (TRR) confirms whether a duct is continuous and suitable for cable/sub duct installation.
We TRR to:
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Confirm continuity between chambers
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Identify restrictions and full blockages
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Validate routes prior to cable blowing or pulling
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Reduce failed installs and remedial civils
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Increase first-time installation success rates
TRR is a critical step before:
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Fibre Optic Installation Services (internal link)
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Cable Blowing Services (internal link)
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Sub Duct Installation Services (internal link)
Why we test rod and rope:
Desilting of Silted Ducts
Silted ducts are common where there is water ingress, ageing infrastructure or poor drainage. Silt and debris can reduce the available space inside a duct and significantly increase friction during installation.
Where appropriate, we provide duct desilting to:
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Remove sediment and debris
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Restore internal clearance
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Improve cable pulling/blowing success
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Reduce the need for excavation when the issue is sediment rather than collapse
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Desilting can be a cost-effective step that turns an “unusable” route back into a viable installation path.
Blocked Duct Investigation – How We Pinpoint the Exact Location
If we find a blocked duct, our method is designed to reduce guesswork and help civils teams excavate precisely.
Bi-directional rodding
(from both chambers)
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When a duct link between chambers is blocked, we:
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Rod from Chamber A toward Chamber B and measure the distance achieved
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Rod from Chamber B toward Chamber A and measure the distance achieved
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Use both measurements to calculate the precise blockage position within that link
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This improves accuracy and reduces unnecessary digging, cost and disruption.
A55 blockage reporting for civil engineering clearance
We then complete a compliant A55 blockage report so civil engineering teams know exactly where to excavate and repair. Our reports include:
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The specific duct link (between chambers)
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Measured distances from both directions
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Estimated blockage point location
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Notes, photos and any safety/condition observations
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Supporting references for GIS mapping where required
Civil engineering teams can then excavate at the correct point, clear the blockage and complete the repair so cables and sub duct can pass, allowing the fibre build to progress.
Underground Cabling, Sub Duct Installation & Cable Blowing Support
Once ducts are validated and cleared, we support underground build delivery including:
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Underground fibre optic installation
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Sub duct installation and recovery
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Assisted preparation for cable blowing and deployment
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Access and spine network build support
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Testing and certification where required
GIS Mapping & Client Handover Documentation
We provide structured, client-ready outputs to support planning, build and long-term maintenance, including:
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Chamber schedules and survey reports
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TRR results and route validation notes
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A55 blockage reports
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GIS outputs (KMZ/KML/CAD/shapefile formats where required)
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As-built documentation packs and handover files
This ensures your teams have reliable information for civils, design updates and asset management.
Accreditations & Standards
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Openreach PIA accredited contractor
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NRSWA accredited (Street Works qualified)
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UKAS ISO 9001 – Quality Management
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UKAS ISO 14001 – Environmental Management
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UKAS ISO 45001 – Occupational Health & Safety
Underground cabling FAQ
Request a Quote
If you need underground duct surveying, TRR, desilting, A55 blockage reporting, or underground cabling support, contact TNS Comms.
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Call: +44 1270 297691
Email: enquiries@tnscomms.co.uk
