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Variety of configurations
Over the years, the technology of profilers has advanced to improve their accuracy. "The information captured by today's profilers is much more accurate than that from profilographs," Klatt says.

The data gathered offers a true elevation profile that plots a California profilograph or rolling straightedge; and it calculates the International Roughness Index (IRI), a Profile Index (PI), Half-car Roughness Index (HRI), Ride Quality Index (RQI), and Ride Number (RN).

According to Reid, more states are going to IRI, since it better reflects what the public feels when driving on a road. "It's based on an algorithm that more heavily rates the short wavelengths like bumps at an expansion joint, but it still counts the longer wavelengths like rolling undulations," he says. "It's more of a true ride reflection."

To help obtain a more accurate IRI number prediction, Ames Engineering developed dual sensor profiler models, which make up the majority of the company's sales. These dual sensor models profile both the left and right wheel tracks as compared to only one wheel track measured with a single sensor system. This results in a more accurate smoothness reading.

Profiler manufacturers have also enhanced laser technology to improve profile accuracy. Initially, single point lasers were used to measure the pavement's smoothness, but contractors soon discovered that a pavement's texture can affect profile numbers.