Evaluation of Technologies for Road Profile Capture, Analysis, and Evaluation

Many transportation agencies in the United States are transitioning to using the International Roughness Index (IRI) in pavement smoothness evaluation as part of an incentive/disincentive program for contractors paving roads. This study evaluates the use of digital levels, inertial profilers, inclinometer-based profilers, and terrestrial laser scanning (TLS) in pavement profile capture and analyses. Traditionally, analyses evaluated elevation differences between profiles. However, evolving standards and procedures perform incremental slope-based analyses to calculate IRI and correlate between profiles, which correspond better to vehicle response. The results of this study show consistent elevation profiles between all of the devices, when operated properly. However, digital levels cannot be used efficiently to capture the road profile at high sampling (<10 cm) intervals for long profiles. Thus, TLS shows additional advantages compared with the other techniques, including the ability to collect a large, dense set of data relatively quickly for the entire roadway and surrounding areas; hence, the data can serve multiple purposes, including validation of other design parameters such as transverse and longitudinal slope. However, TLS requires substantially more processing and training.