Sewers, Culverts & Underground Inspections

Mining, Quarrying & Confined Spaces | Infrastructure & Utilities

Explore the condition of underground infrastructure without unnecessary entry.

Sewers, drainage culverts, tunnels and underground structures perform essential functions, often beneath roads, industrial facilities, developments and operational infrastructure.

Assessing their condition can involve restricted access, poor visibility, hazardous atmospheres, water, obstructions and potentially disruptive access arrangements.

Specialist remote inspection systems, including suitable collision-tolerant drones and robotic crawlers, can help collect visual and spatial information without requiring personnel to enter every structure.

Explore Underground Inspection Solutions

Flybotix ASIO X entering a drainage culvert for remote inspection.

The Challenge

Critical infrastructure that is difficult to see, access and assess.

Underground drainage and utility structures are often hidden from view, making it difficult to understand their condition without a planned inspection.

Deterioration, displaced joints, deposits, debris, erosion, root ingress or structural damage can affect the serviceability of an asset.

Traditional inspection may require personnel entry, specialist access equipment or CCTV systems introduced through suitable openings. Physical constraints, flow conditions and atmospheric hazards can complicate the work.

Appropriate remote inspection technology can help owners document accessible concerns and determine where further investigation is needed.

Questions That Matter

Is the structure visibly deteriorating?

Document accessible cracking, joint movement, exposed reinforcement and surface deterioration.

Are blockages affecting the passage?

Identify visible debris, sediment accumulation and other obstructions.

Can personnel entry be reduced?

Evaluate whether a suitable remote system can collect the necessary initial information.

Where should maintenance be prioritised?

Use documented conditions to inform cleaning, repairs and further specialist assessment.

Drone & Remote Inspection Applications

Where can remote systems support underground infrastructure inspections?

From large culverts and drainage tunnels to access chambers and underground structures, the appropriate inspection method depends on the environment and the information required.

01 / Drainage Infrastructure

Culvert Inspections

Document internal surfaces, joints, visible cracking, erosion, sediment and obstructions within suitably accessible road, rail and watercourse culverts.

02 / Wastewater Infrastructure

Large-Diameter Sewer Inspections

Collect visual evidence within suitable sewer structures, taking account of flow conditions, access dimensions, atmospheric hazards and equipment limitations.

03 / Underground Structures

Tunnels & Underground Passages

Examine accessible linings, walls, soffits, structural supports and other visible features within suitable service tunnels and underground passages.

04 / Access Structures

Chambers, Shafts & Manholes

Obtain visual records from appropriate vertical shafts and access chambers, reducing the need for some preliminary physical entry.

05 / Structural Condition

Cracks, Joints & Surface Deterioration

Capture accessible visible defects, including cracking, displaced joints, exposed reinforcement, lining damage and potential water ingress.

06 / Water Management

Outfalls & Drainage Connections

Document accessible outfalls, culvert entrances, drainage connections and discharge structures to support condition assessment.

07 / Spatial Information

Internal Mapping & 3D Records

Where supported by the selected system, collect spatial information or organised imagery to document underground geometry and accessible features.

08 / Asset Management

Repeat Condition Inspections

Develop dated visual records that support comparisons between inspections and help identify changes requiring engineering attention.

From Access Planning to Asset Evidence

Understand the environment. Select the method. Capture the evidence.

Effective underground inspections begin by understanding access restrictions, flow conditions, atmospheric hazards and the required level of information.

01. Assess & Prepare

Review access dimensions, atmospheric hazards, water flow, isolation, communications and recovery arrangements.

02. Inspect & Capture

Use a suitable drone, crawler or camera system to document accessible surfaces and visible conditions.

03. Review & Report

Organise collected evidence for engineering review, asset management and further maintenance planning.

Technology in Action

Flying drones, robotic crawlers and inspection cameras each have their place.

Underground structures can be GPS-denied environments with no natural lighting and restricted communications. Selecting the correct inspection system is essential.

Collision-tolerant drones: May suit large culverts, chambers, tunnels and other structures with sufficient space for controlled flight.

Robotic crawlers: Often better suited to narrow sewers, pipes and long restricted routes where flying is impractical.

Inspection cameras: Pole or push-rod cameras may be more appropriate for shorter, restricted-access inspections.

Inspection lighting: Provides illumination for documenting accessible linings, joints, surfaces and structural details.

Spatial data: Selected specialist platforms can collect mapping information where their sensors and the environment permit.

The most appropriate equipment is determined by the inspection objective and operating constraints, not simply by whether a drone can fit through the opening.

Inspection Technology Explained

UAS

Collision-Tolerant Drones

Remote visual inspection in sufficiently spacious and suitable underground structures.

CCTV

Robotic Crawlers

Ground-based inspections for pipework and appropriately sized sewer systems.

LED

Inspection Lighting

Illumination of underground surfaces and structural details.

RGB

High-Resolution Cameras

Visual documentation of accessible defects and obstructions.

Spatial Mapping

Optional geometric and digital asset records from suitable specialist systems.

Understanding Underground Inspections

Can a drone replace a conventional sewer or culvert inspection?

Sometimes a specialist drone is the right approach. In other circumstances, CCTV equipment, a robotic crawler or a physical inspection remains necessary.

Where Drones Can Add Value

Large culverts, shafts, chambers and tunnels may provide enough room for a suitable drone to capture visual information without personnel entry.

Flying platforms may also allow observation of elevated soffits and features that are difficult to examine using ground-based equipment.

Where Other Methods Are Better

Narrow pipes, submerged sections, high water flow and severe communication restrictions can make aerial inspection unsuitable.

A crawler or other CCTV system may deliver better access, stability or compliance with formal pipe-condition survey requirements.

Important distinction:
A remote visual survey does not automatically constitute a complete structural assessment or standardised sewer condition survey. Where formal defect coding, measurement accuracy or statutory requirements apply, the inspection system and reporting method must meet those requirements.

Specialist Inspection Technology

Purpose-built equipment for spaces conventional drones cannot easily enter.

Collision-tolerant systems such as the Flybotix ASIO X illustrate how specialist inspection technology can access suitable confined structures, subject to environmental and operational assessment.

Flybotix ASIO X collision-tolerant drone in an underground tunnel inspection setting

Underground Structural Inspection
Specialist drones can document accessible surfaces, structural supports and visible deterioration within suitably sized tunnels and underground passages.

Caged ASIO X specialist drone photographed inside an underground rock passage

Restricted Underground Access
Purpose-designed systems may help inspect accessible rock faces, cavities and structures that would otherwise require more challenging access arrangements.

Equipment selection matters:
Flight space, access openings, lighting, communications, water, atmospheric conditions and recovery arrangements determine whether a drone is suitable. A collision-tolerant design does not make a system appropriate for every underground environment.

Safety & Operational Suitability

Underground inspections demand careful risk assessment.

Remote technology may reduce the need for personnel to enter certain structures, but underground environments can remain hazardous even when inspection operators work from outside.

01 / Atmosphere

Gas & Oxygen Hazards

Underground structures may contain toxic gases, oxygen-deficient conditions or potentially flammable atmospheres requiring suitable controls.

02 / Water Conditions

Flow, Rainfall & Flooding

Changing weather, rising water and unexpected flow increases can affect access, inspection feasibility and safe recovery.

03 / Recovery

Communications & Retrieval

Long passages and underground geometry can affect communication links. Contingency and equipment-recovery plans are essential.

Critical safety consideration:
Collision-tolerant drones are not automatically suitable for explosive atmospheres. Any applicable hazardous-area classification, ATEX equipment requirements, atmospheric testing, isolation and confined-space procedures must be considered. Recovery arrangements must not rely on unplanned personnel entry into a hazardous structure.

Why It Matters

Reduce unnecessary entry. Identify concerns. Plan the next action.

Suitable remote inspection methods can give infrastructure owners useful visual information while reducing some of the difficulties associated with restricted or hazardous access.

Support Safer Access Decisions

Initial remote observations may reduce unnecessary entry and help plan essential physical inspections.

Focus Maintenance Activity

Visual findings can help identify areas requiring cleaning, repair or further specialist examination.

Improve Asset Records

Organised imagery and suitable spatial information support infrastructure documentation and condition comparisons.

Planning Underground Inspections

Every structure needs the right inspection approach.

Not every culvert, sewer or underground asset is suitable for a flying drone. The most effective approach starts with the condition of the structure and the required inspection outputs.

Asset dimensions: Review diameter, length, opening sizes, internal geometry and obstructions.

Water conditions: Consider depth, flow rates, recent rainfall and potential flooding.

Atmospheric hazards: Assess gas, oxygen conditions, potentially flammable atmospheres and equipment suitability.

Communications: Determine whether reliable control and data links can be maintained.

Inspection outputs: Agree visual detail, asset identification, defect records and any required formal condition coding.

Further assessment: Identify how suspected structural concerns will be investigated and reviewed by competent specialists.

Planning Considerations

What should infrastructure owners consider?

What structure is involved?

Culvert, sewer, tunnel, access shaft, chamber or another underground asset.

What physical restrictions apply?

Consider access dimensions, length, water, debris and internal geometry.

What hazards must be controlled?

Review atmosphere, changing flows, site access and emergency arrangements.

Which technology is suitable?

Compare drones, robotic crawlers, inspection cameras and conventional methods.

How will the results be used?

Agree reporting, engineering review, maintenance decisions and any further survey requirements.

Discover What’s Possible

A clearer understanding of the infrastructure beneath your site.

From drainage culverts and large sewers to tunnels, chambers and underground structures, suitable remote inspection technology can help document conditions and plan further investigation.

Talk to Iprosurv about specialist drone inspection solutions, equipment selection, training and operational consultancy for challenging underground environments.

Discuss Your Inspection Requirements

Call 0114 4055 007

Other sectors

Iprosurv drones in your industry Bridges and Civil Infrastructure Inspections

How can we help?

Whatever you need drones to do, there are three ways to work with Iprosurv.

We do it for you

Our pilots carry out the survey or inspection and deliver the data and reports you need.

Drone services

We show you how

Accredited courses that give you and your team the skills to fly safely and legally.

Drone training

You do it yourself

The drones, sensors and software to run your own operations, with expert advice.

Shop equipment

Not sure what you need?

Tell us what you are trying to achieve and we will recommend the right service, training or equipment.

Make an enquiry