The effect of faulting on IRI values for jointed concrete pavements

Abstract

This paper presents a study on the effects that faulting of joints and cracks in concrete pavements have on International Roughness Index (IRI) values for the pavements. Three methods for comparing faulting to IRI values for roadways are evaluated in this study. The first method is a parametric study on the effect that idealized faulted profiles consisting or rotated line segments having various slab lengths and fault sizes (a saw-tooth pattern) have on IRI values. The second method is a road profile based fault size estimation routine using data from non-contact moving road profilers. Profile based faulting estimates were obtained from over 1000 GPS3 pavement profiles. The third fault measurement method evaluated is the official LTPP field measurement of faulting using the Georgia Faultmeter. This direct measurement method uses the Faultmeter placed over each joint to measure fault sizes. Faulting and IRI can be presented in the same units, m/km (in/mi) for comparison purposes. Based on this study, faulting along the roadway has gain of about 1.75 when converted to IRI. In other words for each 1.58 m/km (100 in/mi) of faulting present, about 2.76 m/km (175 in/mi) of IRI will develop, with gain increasing slightly with increasing fault spacing. The IRI gains measured for real pavement faulting matches the gain values calculated for the ideal saw-tooth patterns. Faulting data can be reliably obtained from relatively inexpensive road profile data that is being obtained for major roadways.