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METHOD 01 · ROADS

Ground-penetrating radar for roads

A vehicle-mounted GPR sees inside the pavement over long corridors, at traffic speed and without closing the road.

THE METHOD

How it works

An array of GPR antennas is mounted on a vehicle. Each antenna sends very brief electromagnetic waves into the ground and records what comes back. At each change of material (asphalt, aggregate, soil), part of the wave is reflected. The return time gives the depth of the interface, and the signal strength indicates the condition of the layer.

Several antennas side by side cover the full width of a lane in a single pass. A precision GNSS receiver (RTK) gives each measurement a centimetre-level position. The data is then processed in the office, interpreted by a geophysicist, and delivered as maps and profiles.

WHAT IT IS FOR

The problems the method solves

  • Know the thickness of each layer of the pavement without systematic coring.
  • Spot voids, potentially wet zones and delamination before they turn into potholes or subsidence.
  • Highlight the homogeneous and weak sections of a route to prioritise works.
  • Check thickness compliance after rehabilitation or construction works.
  • Target a few cores and test pits at the right places, instead of spreading them at random.
WHAT YOU RECEIVE

The results we deliver

Layer thicknesses

Thickness maps and profiles for the wearing, base and subbase courses, with interface continuity.

Anomaly map

Location of voids, potentially wet zones and delamination, identified along the corridor and ranked by intensity.

Usable data

Georeferenced data, exportable to GIS and CAD, interpretation report and optional georeferenced 3D model (BIM).

Reference practice: IDRRIM guide and ASTM D4748 standard (pavement thickness).

HOW TO USE IT

What this changes for your decisions

  • A map of the zones to treat first, with their exact position, to plan maintenance and estimate its budget.
  • An objective basis to justify a funding request to a funding partner.
  • A dated baseline of the network: a new campaign a few years later makes it possible to measure the evolution.
  • Data that fits into your existing tools (GIS, plans, digital models).
OUR EQUIPMENT

The equipment selected

IMPULSERADAR · RENTED (GEOREVA)

Raptor 3D

Multichannel GPR array mounted on a vehicle, designed for the inspection of roads and structures.

At a glance

  • Raptor-45 version: 18 channels, centre frequency 450 MHz (range 225–625 MHz)
  • Acquisition speed above 100 km/h according to the manufacturer; we adapt the speed to traffic safety
  • Positioning by GNSS, wheel odometer or total station

Why this choice

A single pass covers the full width of a lane: depending on the site, tens of kilometres can be inspected per day, without cutting traffic. A single-antenna GPR covers only a narrow strip and therefore needs many more passes, more time and more staff exposure to traffic.

EMLID · GNSS RTK

Emlid Reach RS3

Precision GNSS receiver that provides a position for each measurement.

At a glance

  • Centimetre-level positioning with RTK
  • Compatible with common GIS and CAD software

Why this choice

An anomaly is only useful if you know exactly where it is. Georeferencing makes it possible to return to the precise point, compare two campaigns and integrate the results into plans.

Equipment selected for our first campaigns, being acquired, rented or provided through partnerships depending on the instrument; availability is confirmed when the order is placed. Characteristics as stated in the manufacturers' data sheets; they depend on configuration and terrain.

LIMITS

What the method does not do

  • Investigation depth depends on frequency and soil: very thin layers require higher-frequency antennas.
  • GPR provides thicknesses and anomalies, not bearing-capacity or strength values. A few calibration cores improve accuracy.
  • A very wet pavement or a high salt content reduces the usable depth.

A corridor or structure to inspect? Let's talk about your need.

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Other methods

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