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Ontario’s Move to Hot Mix Asphalt Pavement Smoothness Acceptance Using High Speed Inertial Profilers


The Ministry of Transportation Ontario (MTO) implemented a smoothness specification for newly constructed hot mix asphalt paving in 1997. Smoothness data collected since have shown that the ride quality of newly constructed asphalt pavements on Ontario highways has improved by about 25 percent. Up until 2010, the smoothness of new asphaltic pavements was accepted based on Profile Index (PI), measured by California profilographs. These 7.6 m long manual profilographs are operated at walking speed, measure one wheel path at a time and require lane closures. Therefore, MTO and the Ontario hot mix asphalt industry sought an alternative device that would be faster and safer to operate, alleviating the need for lane closures. MTO conducted several studies to evaluate high speed inertial profilers which can measure both wheel paths simultaneously. Technical and financial comparisons were made between high speed profilers and California profilographs, leading to development of smoothness acceptance criteria based on inertial profiler measurements that were comparable to the existing smoothness criteria for California profilographs. The correlation between the data obtained by both devices was excellent and supported the phased-in use of high speed inertial profilers for acceptance on selected contracts in 2010 and 2011 with full implementation in 2012. MTO adopted the ProVAL software program to calculate International Roughness Index (IRI) and identify localized roughness. This paper presents the transition from the TxDOT algorithm in ProVAL to the Smoothness Assurance Module (SAM) of ProVAL version 3 to identify localized roughness. In the 2010 and 2011 construction seasons, MTO conducted extensive analyses in collaboration with the Ontario hot mix asphalt industry to develop comparable acceptance thresholds between the two algorithms. From these analyses, a two-category payment reduction system was developed, to replace the former three-category system, for localized roughness. This paper reports on studies supporting the transition from California profilographs to high speed inertial profilers, and the analysis that led to development of acceptance criteria for localized roughness based on the ProVAL Smoothness Assurance Module. The paper also provides an overview of the challenges that were faced during implementation of high speed profilers and how they were overcome.

Conference Paper Details

Session title:
Seyed Tabib
Chris Raymond
Alexander (Sandy) Brown
Pamela Marks