DMRC and NCRTC GPR Survey for Pier, Station and Ramp Works

What does a metro utility diversion survey do?

It finds every underground service where a metro structure will go, such as a pier footing, station box, entry building or ramp, and records its position and depth. The diversion team then knows exactly what must move, how far and in what order, before piling or excavation starts.

Delhi Metro Rail Corporation is a joint venture of the Government of India and the Government of NCT of Delhi, set up in 1995. It opened its first section in December 2002 and is now building Phase 4. The National Capital Region Transport Corporation is owned jointly by the Government of India and the states of Delhi, Haryana, Rajasthan and Uttar Pradesh. It runs the Delhi–Ghaziabad–Meerut RRTS, whose Namo Bharat trains began service on the first section in October 2023. Both build through the busiest roads in the region, where decades of utilities lie under every metre.

Why do pier footings need a grid, not a line?

Because a pile group occupies an area, and a service crossing anywhere inside it is a clash. An elevated viaduct sits on piers in the road median or along one edge of the carriageway. Each footing, with its pile cap and working space, covers a patch several metres across. A single scan line through its centre can miss a cable passing at the corner.

We therefore scan each footing location as a grid, with lines in both directions at close spacing, extended over the working area of the piling rig. Ground penetrating radar (GPR) suits this. Each pass fires radar pulses into the median and the receiving antenna logs every echo, so the grid builds high resolution imaging of the footing. Between footings, a lighter pattern picks up services running along the median that may need diversion as a whole. Medians often hide more than people expect. Street-light and signal cables, irrigation lines and sometimes a trunk main or duct bank sit there, because it was the only free space.

What changes for an underground station box?

The area is much larger, the services are deeper and the diversion is staged around traffic. Underground stations are commonly built as cut-and-cover boxes, with the road above diverted in phases. Every utility crossing the box footprint, and every one running alongside it within the zone of the diaphragm walls, must be moved or supported.

1. We scan the full box footprint plus a margin on each side.
2. Deep or uncertain services are flagged for trial pits, since GPR depth in Delhi's alluvium varies with moisture and soil conditions.
3. The drawing is split by traffic phase, so each phase's diversion can be planned separately.
4. Entry and exit structures, ventilation shafts and chiller areas are scanned as separate small grids.

Metro diversion survey at a glance

Most diversion delays trace back to a few repeat errors on site; we have collected the common digging mistakes Delhi NCR explained in a separate post.

Which utilities cause the most trouble?

Telecom ducts, because there are so many of them and so few records. A single arterial road in Delhi can carry ducts from several operators, plus old copper cables, and owners must be traced before anything can move. The scanning is the same as for any fibre route; see what we do: OFC route GPR survey for the method. Since operators are the owners most often contacted for diversion, our page on telecom operator projects also explains how they handle their own routes.

Large water pipes and sewer mains are fewer but harder to move, and their depth matters most for pile and wall design. HT cables of the distribution companies need planned shutdowns. Gas lines, where present, need their owner's supervision.

Abandoned services are the hidden cost. An old cast iron main or a dead cable left in the ground is still a buried object on the radar, and it still blocks a pile. Owners are often reluctant to confirm that a line is dead, so we record every target, live or not, and let the diversion team settle its status with the owner.

How do we work on live metro corridors?

Mostly at night, inside the contractor's barricading, under its traffic management plan. Arterial roads in Delhi, Ghaziabad, Gurugram and Faridabad rarely allow daytime lane closures. Our crews are used to short night windows: set up quickly, scan the footings released for that night, mark them and clear the road before the morning peak.

Where barricading is already in place for the works, we can scan by day inside it. Every crew member wears high-visibility clothing, and our safety system is certified to ISO 45001.

What does a diversion survey cost?

We charge per metre of scan line: ₹24 for standard scanning and ₹32 for an L-section, plus GST. The minimum order is ₹50,000 in Delhi NCR and ₹1,00,000 elsewhere. Orders above 100 km get 25% off the whole order, above 500 km 40% and above 1,000 km 50%.

• A 6 km viaduct stretch, scanned along both sides of the median, is 12 km of lines: 12,000 × ₹24 = ₹2,88,000 plus GST.
• A station box of about 220 m by 25 m, scanned closely in both directions with margins, might need around 6 km of lines. That is roughly ₹1,44,000 plus GST.

Exact quantities depend on the grid spacing agreed with your designer. See GPR survey rates details for all slabs.

Who engages us on metro and RRTS work?

DMRC and NCRTC on direct work orders, plus the civil contractors, diversion sub-contractors and design consultants on their packages. Company names on this page are used only to describe the type of work; all trademarks belong to their owners. Our crews are our own and our staff live across Delhi NCR, so most corridor sites see radar on confirmation day, or by the close of the next business day. Share the footing schedule or station layout and book a survey slot.

Frequently asked questions

Can you scan only the footings released each night?

Yes. We plan the scan list nightly with your site team and report each footing separately.

How deep can you see under Delhi roads?

In dry alluvium often 2–3 m, less in wet or clay-rich ground, where electrical conductivity is higher. Deeper services are confirmed by trial pits.

Do you trace the owner of each duct?

Our data collection records markers, chamber covers and any visible labels. Ownership is confirmed with the agencies during diversion.

Can you survey a trenchless crossing for a diverted utility?

Yes. We run an L-section along the bore line; there are details of HDD route survey on our service page.

Do you scan inside depots?

Yes. A GPR survey of the depot covers cable trenches, drains and foundations ahead of new works and adds to its underground utility mapping.

Is daytime work possible?

Inside existing barricading, yes. Open carriageways need night work in most cases.

Written by Saniya Parveen · Technically reviewed by Rahul Rai · Updated 8 November 2026