Development and Implementation of Stop-and-Go Inertial Profiler Certification Procedure in California

The ride quality of a road in California is often determined by evaluating pavement smoothness using an inertial profiler (IP). Conventional IP technology, per California Test (CT) 387, requires IP operators to maintain a minimum speed of 15 mph to collect pavement-smoothness data. However, maintaining a minimum speed of 15 mph in busy urban areas or on hilly terrains can be difficult and unsafe, often requiring traffic control. Caltrans and industry have identified a new technology, the “Stop-and-Go” (SAG) IP, for collecting pavement-smoothness data at low speeds (under 15 mph) without traffic control. The previous version of CT 387 did not allow for the use of SAG IPs. To address this issue, the Pavement and Materials Partnering Committee (PMPC) evaluated SAG IP and updated CT 387. A certification procedure for SAG IP was developed, and included in CT 387, based on a series of runs using speed profiles under various braking and acceleration conditions simulating urban traffic conditions. Any SAG profiler can be certified if it meets the requirements of AASHTO R 56 and CT 387. The certification procedure was validated using qualification runs at the Caltrans certification track, along with field testing, demonstrating that SAG IPs provide similar results to conventional IPs. Based on the validation, along with the subsequent update of CT 387, the PMPC approved the implementation of SAG IPs for optional use by Caltrans and industry. These developments helped California become one of the first states to develop and implement a certification procedure for SAG IPs.