U.S. Department of Transportation
Federal Highway Administration
1200 New Jersey Avenue, SE
Washington, DC 20590

Skip to content

Federal Highway Administration Research and Technology
Coordinating, Developing, and Delivering Highway Transportation Innovations

About LTPP | Data Collection | Analysis | Products | Pooled Fund Studies | Operations/Analysis Feedback Reports | Publications | Projects |
Customer Survey
| Contact



LTPP Publications


Publication Details

Quantification of Smoothness Index Differences Related to Long-Term Pavement Performance Equipment Type

Primary Topic: Surface and Other Considerations

Description: The main objective of this project is to quantify and resolve the differences in the longitudinal profile and roughness indices that are attributable to the different profiling equipment that have been used in the LTPP program. The Long-Term Pavement Performance (LTPP) program was designed as a 20-year study of pavement performance. A major data collection effort at LTPP test sections is the collection of longitudinal profile data using inertial profilers. Three types of inertial profilers have been used since the inception of the LTPP program: (1) K.J. Law Engineers DNC 690 incandescent profilers, (2) K.J. Law Engineers T-6600 infrared-system profilers, and (3) ICC laser profilers. The following analyses were performed for this research project: (1) investigate data collection characteristics and compare profile data collected by the different inertial profilers, (2) compare International Roughness Index (IRI) values obtained by the different inertial profilers, (3) investigate factors that contribute to differences in IRI for data obtained from profilers and DipstickĀ®, and (4) identify problems with equipment functionality and current data collection and processing procedures. The analysis indicated good agreement of IRI values among the different inertial profilers that have been used in the LTPP program.

FHWA Publication Number: FHWA-HRT-05-054

Publication Year: 2005

Document Links: HTML  PDF (file size: 3 mb)

PDF files can be viewed with the Acrobat® Reader®



Office of Infrastructure R&D Links

» Office of Infrastructure R&D
» Infrastructure R&D Program
»Long-Term Bridge
  Performance Program

»Long-Term Pavement
  Performance Program
» Infrastructure R&D Experts
» Infrastructure R&D Laboratories
» Infrastructure R&D Projects
» Infrastructure R&D Publications
» Infrastructure R&D Topics


LTPP Email Distribution List

» Contact LTPP Customer Support Service Center at ltppinfo@dot.gov if you would like to be added to our email distribution list for LTPP Newsletters and other announcements.


FHWA Pavement Links

» Design
» Construction
» Preservation
» Maintenance
» Management
» Rehabilitation


More Information



» LTPP Team Leader
Jean Nehme
» Customer Service
Federal Highway Administration | 1200 New Jersey Avenue, SE | Washington, DC 20590 | 202-366-4000
Turner-Fairbank Highway Research Center | 6300 Georgetown Pike | McLean, VA | 22101