Purdue radar technology estimates location, orientation, radius of underground pipes

WEST LAFAYETTE, Ind. — Purdue University engineers have developed a patent-pending method to decrease hazardous strikes to underground utility pipes during construction projects. This could lower related financial losses, service disruptions, injuries and fatalities.

Hubo Cai and Yuxi Zhang are improving upon traditional ground-penetrating radar (GPR) data to better estimate the location, orientation and radius of underground utility pipes. Cai is a professor and the associate head of Purdue’s Lyles School of Civil and Construction Engineering and Zhang is a doctoral candidate in civil engineering.

Cai said GPR provides a nondestructive technique to locate pipes by analyzing the electromagnetic wave reflections and resulting hyperbolic reflections. But it often overlooks inherent uncertainties and issues related to data quality.

“Our uncertainty-aware model compensates for this gap by robustly quantifying uncertainty in order to create a buffer zone,” he said. “With this improvement, construction contractors, utility-locating service providers and excavator manufacturers can better interpret GPR data, supporting safer and more effective underground utility mapping.”

Cai and Zhang’s research has been published in the January 2026 issue of Advanced Engineering Informatics.

They disclosed the innovation to the Purdue Innovates Office of Technology Commercialization, which has applied for a patent to protect the intellectual property. Industry partners interested in developing or commercializing the algorithm should contact Parag Vasekar, business development and licensing manager — physical sciences, at psvasekar@prf.org about track code 71294.

Validating the Purdue solution

Cai and Zhang’s research uses a Bayesian framework for quantifying uncertainty in estimating underground pipe depth, horizontal position, orientation and radius.

“A forward model was developed for predicting electromagnetic wave travel times from 3D pipe geometries,” Cai said. “We also created a statistical inference framework for quantifying uncertainties in estimated pipe parameters. The framework was shown to output credible intervals and provide measures of estimation reliability.”

Cai and Zhang also developed diagnostic metrics for GPR data quality, including quantitative measures of completeness and consistency.

“The forward model achieves an RMSE (root mean square error) of 0.454 ns when validated against high-fidelity simulations, demonstrating strong predictive accuracy with reduced computational cost,” Cai said. “Among all configurations, the VI+MCMC (Variational Inference and Markov Chain Monte Carlo) approach using a normal likelihood model yielded the highest average coverage rates — 97.5% on simulated data and 77.5% on field data — validating the effectiveness of the framework.”

The National Science Foundation supported Cai and Zhang’s work with a grant.

The cost of damaged underground pipes

Zhang said the Common Ground Alliance estimated in 2019 that the annual total social costs of underground infrastructure damage in the United States reached approximately $30 billion.

“According to the 2022 Damage Information Reporting Tool, 87.84% of these incidents resulted from inaccurate location information,” she said.

The lack of complete and reliable records also creates a bottleneck in transportation project delivery attributed to utility conflicts, construction activities or phasing, existing utilities, or failing to comply with accommodation policies and safety regulations.

“Failure to promptly identify and resolve utility conflicts leads to cost overruns, schedule delays, public safety hazards and service outages,” Zhang said. “Therefore, effective tools for locating underground pipelines are the first step toward building a digital twin of the massive underground infrastructure.”

About Purdue Innovates Office of Technology Commercialization

The Purdue Innovates Office of Technology Commercialization operates one of the most comprehensive technology transfer programs among leading research universities in the U.S. Services provided by this office support the economic development initiatives of Purdue University and benefit the university’s academic activities through commercializing, licensing and protecting Purdue intellectual property. In fiscal year 2025, the office reported 161 deals executed with 269 technologies licensed, 479 invention disclosures received, and 267 U.S. and international patents received. The office is managed by the Purdue Research Foundation, a private, nonprofit foundation created to advance the mission of Purdue University. Contact otcip@prf.org for more information. 

About Purdue University

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