Pre-Excavation Underground Scanning & Utility Strike Prevention

Rates and page checked: 23 October 2026

What are pre-excavation underground scanning services?

They are a short, focused survey of the ground that is about to be opened. Instead of mapping a whole corridor for design, the crew looks only at the dig zone – the trench line, pit, pile cap or road cut – plus a working margin around it, and answers one question: what could the excavation hit?

Mezux Touch provides pre-excavation underground scanning services with company-owned GPR systems and EM locators, run by our own crews. A typical job delivers three things:

1. Surface marks painted or pegged over every service found inside the zone, with approximate depth noted beside each mark.
2. A clear-zone statement showing which parts of the footprint showed no services, and which could not be scanned.
3. A signed report listing each find, the method that detected it and the confidence attached to it.

The aim is practical. The excavator operator and the site supervisor should be able to look at the ground and know where machine digging is reasonable and where hands and hand tools must take over.

Which kinds of excavation should be scanned first?

Any cut in ground that holds services carries strike risk, but some excavations meet buried lines far more often than others. The table below shows where we usually start.

For whole plots before setting out, our construction site GPR survey is the better fit, and planned bores are covered by the HDD route survey.

How does a utility strike prevention survey run on the day?

A utility strike prevention survey follows a fixed sequence, so nothing depends on one operator's memory:

1. Walk the zone. The crew notes every surface clue – valve covers, chambers, poles, feeder pillars, marker stones, patched road strips and cable risers – because each one hints at what lies below.
2. Sweep with the EM locator. A passive sweep picks up cables carrying current. Where the client can give access at a pillar, chamber or exposed end, we apply a signal and trace that specific line.
3. Run radar lines. GPR covers the full footprint and margin in parallel lines, then across them, picking up plastic pipes, ducts and drains that EM cannot detect.
4. Compare and resolve. Radar and EM results are checked against each other, and any reflection that does not fit is rescanned before it is marked.
5. Mark and brief. Finds are painted in the colour code agreed with the client, depths are written alongside, and the supervisor is walked through the marks before the crew leaves.

The difference between the two instruments is explained in our article on EM cable locators versus GPR.

What does an underground hazard detection survey look for besides cables?

Live services are the obvious danger, but they are not the only thing that stops a dig. An underground hazard detection survey also reports:

• Gas pipelines, which carry the gravest consequence if struck; steel lines respond to EM, while polyethylene pipes rely on radar and sometimes on a tracer wire.
• Voids and soft pockets under a road or footpath, often left by leaking pipes or washed-out backfill, which can collapse when a machine stands over them. Our void detection service deals with these in more depth.
• Abandoned lines that may not be abandoned at all – a cable thought dead can still be fed from another end.
• Buried chambers and old foundations that stall a trench or deflect a pile.
• Earthing strips and rods close to substations and poles.

Each is listed with its own note, so the site team can treat a void differently from a cable.

Where does scanning stop and hand digging take over?

Radar and EM give approximate positions and depths, not millimetre answers. Signal reach falls in wet clay and saline ground and improves in dry sandy soil, and very small or deep lines can be faint. A responsible pre-dig scan therefore ends with a clear handover:

• Near any mark, the crew should expose the service by hand or with hand tools before a bucket goes in, within whatever safe distance your own safety rules set.
• Where the report gives low confidence for a line, treat the whole uncertain band as occupied.
• If the alignment shifts after the scan, the new stretch should be scanned before it is dug.
• When a depth has to be proved, trial pits or boreholes can be ordered at the critical points.

Why this discipline matters, and how strikes usually happen despite drawings, is discussed in our blog on utility mapping and strike prevention.

How is pre-excavation scanning priced?

Scanning is charged by the metre of radar line run over the dig zones. The standard rate is ₹24 per metre; where a depth profile of the detected services along a trench is required as an L-section, the rate is ₹32 per metre. An order is never billed for less than 4 km. Inside Delhi NCR that is the only minimum; elsewhere, each project also carries a ₹1,00,000 minimum bill. GST is added to the total.

• 25 km of road cutting in Delhi NCR, standard: ₹6,00,000 before GST.
• 2 km of trench outside NCR: billed as 4 km (₹96,000), then raised to the ₹1,00,000 project minimum.
• 10 km trench with L-section: ₹3,20,000 before GST.
• 150 km of duct cutting in one programme: 25% off every metre, so ₹27,00,000 before GST.

Orders above 500 km get 40% off and above 1,000 km get 50% off, applied to the whole length. Each of these sits outside the metre rate and is quoted on its own: mobilisation, night-shift working, traffic arrangements or permits, and CAD/GIS drawings. Many small pits across a city can be grouped into one order so they clear the minimum together. Check any length against the slabs with the calculator on our GPR survey price list.

Why do contractors book pre-dig scans with Mezux Touch?

Excavation programmes move fast, and a scan that arrives late is no use. We have been doing this work since 2003 and keep the capacity in-house:

• 58 company-owned GPR systems and 18 HDD rigs, with no hired machines and no sub-letting – see our owned machinery.
• 1.5 lakh+ km of GPR survey completed across 28+ States and UTs, with peak output of 100 km a day on open corridors using day and night shifts.
• ISO 45001:2018 for occupational health and safety, alongside ISO 9001:2015 and ISO 14001:2015.
• Crews and systems mobilise from Faridabad, so road-cutting programmes in NCR and other states can be covered by the same team.

For a quote, send the dig locations and dates to kumar@mezux.in or ring +91 99100 10209.