Use of cellphone application to measure pavement roughness

Pavement roughness is the surface unevenness which adversely affects ride comfort. Basically, roughness is computed by measuring the vehicle suspension motion. It is expressed by International Roughness Index (IRI) with a unit of inch/mile or m/km. Roughness is very important information to the pavement management group, and maintenance and rehabilitation decisions are usually taken considering IRI and other distress data. Generally, transportation agencies do not collect IRI data annually for the entire roadway network because it requires a significant financial investment. Different types of tools are currently used to measure IRI, but these are either costly or inefficient. Recently, researchers at the Massachusetts Institute of Technology used accelerometers in cellphones to identify localized pavement defects. In the student presented herein it is shown that a smartphone based application shows great potential to capture pavement roughness as characterized by IRI. The IRI of a pavement section can be conveniently measured in a rapid and highly economical manner using this approach. In this study, three 2-mile long test sites were selected, where each having different levels of pavement distresses and roughness. IRI data was collected using an inertial profiler, and vehicle vertical acceleration data was collected using an android-based cellphone mounted on the dashboard of an inertial profiler van. Acceleration data was analyzed to obtain IRI for every 0.1-mile pavement section. Subsequently, acceleration data was collected from the same test sections using a passenger car. Results showed that the IRI estimated by the inertial profiler and cellphone application to be very similar. Results also compared favorably between trials conducted with the profiler van vs. the passenger car. Updated IRI data can be used to arrive at more effective pavement designs, maintenance, and rehabilitations decision making.