DGPS Survey for Highway Projects: Control, ROW and Utilities

What does a DGPS survey for highway projects deliver?

Fixed points along the corridor with trustworthy coordinates and height, from which every other measurement is taken. On a highway job they do three things at once. They control the topographic and aerial mapping, mark the existing and proposed right of way, and become the contractor's setting-out base.

IRC:SP:19, the Indian Roads Congress manual for survey and investigation of road projects, sets the general expectations for DPR surveys. We work to that or to the consultant's terms of reference, whichever governs, and say so in the method note.

Three kinds of highway job, three survey plans

The density and type of control depend on whether you are building new, widening, or managing an existing road.

Table note: after construction, the same control lets you record what was built; read questions to ask before an as built survey to plan that handover drawing early.

Where should the pillars go on a widening job?

Outside the future construction zone, where no excavator will reach them during the contract. Pillars set on the existing shoulder or median vanish in the first month; it is the most common widening mistake. We place pairs near the proposed right-of-way line on stable ground, inter-visible and tied to benchmarks for height.

On a greenfield alignment the band is wider. Pillars sit along the likely corridor before the final line is chosen, so options can be compared on the same DGPS (differential global positioning system) base.

Ground control for drone, LiDAR and survey vehicle data

Aerial and mobile mapping is only as good as the ground points it is pinned to. For a drone or drone LiDAR flight we measure targets across and along the corridor, plus independent check points left out of processing. The network survey vehicle records roughness, rutting and video with its own GNSS and inertial unit, and surveyed reference points let its chainage be checked against the project frame. India spans several UTM zones, so a long highway crossing a zone boundary may need a project grid to keep scale distortion small. We agree that with the consultant before issuing coordinates.

Along a live highway, take-off points sit well clear of the carriageway, and flights over moving traffic stay within the drone rules and the authority's site conditions.

Right of way, land plans and utility shifting

The same DGPS points fix where today's highway land ends and where the new land begins. Land for national highways is acquired under the National Highways Act, 1956, and the land schedules depend on accurate plans of the proposed boundary against village maps and land records. We set out existing boundary stones where they survive, record walls and encroachments inside the right of way, and prepare chainage-wise plans for the additional strip.

Utilities inside the widening zone, such as poles, water mains, sewers, gas and telecom cables, must be located and costed for shifting. The DGPS work records what is visible; buried lines need radar and locator work. For detail between pillars, follow the topographic survey for road process step by step, and read GPR survey deliverables for how buried lines are reported. NHAI has engaged Mezux Touch directly for corridor surveys, and highway contractors and consultants bring us further stretches.

How a highway control survey runs, week by week

Reconnaissance first, monuments second, observations third, and nothing issued until the network closes. An engineer first drives the corridor with the strip plan, chooses pillar sites with the landowner or highway office and notes surviving benchmarks. Pillars are cast and left to cure, because green concrete moves. In each session a GPS receiver stands on each pillar of a neighbouring pair at the same time, with a third on a reference station where possible. Each baseline is measured twice, on different days or satellite windows.

Processing keeps pace with field work, so a weak baseline is re-observed while the crew is nearby. Levelling runs in parallel between benchmarks. The register goes to the consultant only after the network adjustment passes, with a note on any pillar disturbed or replaced. A 25 km stretch takes two to three weeks of field time, depending on access, crops and traffic.

Rates for highway survey work

Control and corridor detail are priced separately so you can buy only what your DPR scope needs. All figures exclusive of GST:

• DGPS control points along the corridor: ₹3,000 per point.
• Route survey with centreline and cross-sections every 25 m: ₹12,000 per km, minimum ₹50,000.
• Topographic strip survey of the road corridor: ₹15,000 per km.
• Drone mapping: from ₹40,000 per site up to 25 acres, then ₹1,500 per acre; drone LiDAR ₹2,500 per acre, minimum ₹1,50,000.
• Network survey vehicle: ₹4,000 per lane-km, minimum ₹4,00,000.

Example: a 25 km two-lane to four-lane widening with a pillar pair every 500 m needs 51 pairs, or 102 points, which is ₹3,06,000. A topographic strip adds 25 × ₹15,000 = ₹3,75,000. Crews reach NCR corridors the same day or within 1 working day. In other states, our team member based along the corridor starts immediately or within 1 working day, and any mobilisation or travel cost, if applicable, is in the written quote.

Questions to settle before the survey starts

Five answers on paper prevent most disputes later. Which manual or terms of reference govern accuracy? Which coordinate system and height datum? How far apart are pillar pairs, and what type of monument? Who keeps the control register and who may add to it? Which benchmarks will be used for levelling? Our page on questions to ask before a DGPS survey expands on each point. When the brief is clear, talk to the survey desk with the corridor KMZ and chainage limits.

Frequently asked questions

Can DGPS replace total station on a highway survey?

Not fully. DGPS, a form of satellite based positioning, fixes control and open-ground detail quickly. A total station survey is still better under flyovers, near tall buildings and for structure detail.

How far apart should control pillars be on a highway?

It depends on the specification and terrain; pairs every few hundred metres are common on widening jobs, closer at junctions and bridges.

Do you provide benchmarks for the contractor?

Yes, levelled pillars double as benchmarks for construction layouts, and the register lists which ones carry levelled heights.

Is drone mapping accepted for highway DPRs?

Many consultants use it for topography, provided ground control and check points meet the specification they work to.

What about buried services in the widening zone?

They are located with GPR and locators and registered for excavation alerts; read see: Call before You Dig in India for the alert step.

Can you start before the alignment is final?

Yes, control along the likely corridor is useful for every option and stays valid when the final line is chosen.

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