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ITD Vault: 25 Years Ago
Oct./Nov. 1990

Profiler to measure road wear, ruts

Department engineers believe they have a great new tool for collecting pavement management data required by the Federal Highway Administration. It’s a deceptively simple profiler that uses Polaroid camera technology to measure pavement roughness. The South Dakota Road Profiler is the next generation of pavement-roughness measuring equipment, which will also measure rut depths at highway speeds.

The SDR Profiler will help the Department meet FHWA requirements for collecting roughness data, according to Bryon Breen, a pavement management engineer at ITD.

“In addition to meeting the federal requirements, we think this equipment will be a very valuable tool for ITD’s pavement management system,” Breen said.

The equipment is mounted in a van and uses ultrasonic technology to measure pavement roughness and rut depth in each wheel path. Five ultrasonic transducers similar to those used in Polaroid cameras, which provide automatic focus, are mounted in a specially-made front-bumper attached to the van.

The transducers, two mounted in front of the wheels, one in the center and two existing approximately 1.5 feet beyond the width of the van, bounce sound waves off the pavement to take measurements. Two accelerometers are also installed in the bumper in order to remove the van’s vertical movements from the readings.

Breen believes the accuracy of roughness measurements should be greatly improved over the present system.

“The Cox Roadmeter is less accurate than the Profiler because it relies on the movements of the vehicle in which it is installed,” he said. “The readings from the Profiler are independent of the vehicle.”

The ability to gather rut depth measurements at highway speeds should also be useful information, Breen added.

With the information gathered from the Profiler, the Department can predict what sections of road will need rehabilitation due to roughness of the road. By charting the deterioration, roads can be repaired before they get too bad.

From now until the end of the year, crews will be performing calibrations and correlating the readings against the Cox Roadmaster. Statewide testing will begin next summer.

Editor’s 2015 Note: The South Dakota Road Profiler was the precursor to the Pathways RoadRunner Profile van ITD uses each year between spring and fall to gauge Idaho roadways. ITD's Profiler Van is pictured below. South Dakota was the first state to develop a mobile profiler, a machine mounted in a vehicle to measure the roughness, or up-and-down profile, of a roadway in a moving operation. All others developed thereafter were known as South Dakota-type profilers. The current system uses lasers and high-definition cameras to collect roughness, rutting and cracking information on the road surface.