Technology & methods

Reading a radargram: basics for project managers

GPR software shows cross-sections of reflections versus travel time or estimated depth. You do not need to pick hyperbolas by hand—but you should know what honest interpretation claims, and what it does not.

Published Oct 22, 2025 Updated May 10, 2026 ~7 min read By Carter Williams

Scope & limitations

This article orients non-geophysicists. It is not training to override a qualified interpreter on your project.

What you are looking at. A radargram stacks reflected energy along a line on the ground. Bright bands and curved shapes (“hyperbolas”) often mark discrete reflectors—pipes, ties, changes in stratigraphy, or clutter. The vertical axis may be time or depth; depth requires a velocity model that can be wrong if moisture changes.

Why one feature is not one pipe. Migrated or processed views can look cleaner than raw data. Multiple targets can interfere. That is why field correlation—covers, vaults, occupancy, potholing when scoped—still matters for high-consequence digs.

Public-domain example

Wikimedia Commons hosts GPR profile examples useful for orientation—e.g. LINE21.jpg (historic cemetery depth section, Alabama) with annotated hyperbola discussion on the file page. We are not embedding it here; follow the link for the reference image.

From lines to deliverables

When your PO includes PDFs, expect limitations language that matches the data—not certainty to the inch. Pair this note with deliverables after a GPR locate and limitations in GPR reports.

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