IRI Smoothness Testing for Quality Assurance and Warranty Construction Alberta Transportation CUPGA November 15 th, 2009 Moncton, NB

AT Construction Smoothness Practices Alberta Transportation (AT) has used the California Profilograph since the early 1980’s. –Full implementation of End Product Specifications for smoothness by the early 1990s. –Profile Index (PrI) assessment based upon 100 m sublot –PrI criteria for: Multi-lift Single lift Curb & gutter –Bump/Dip assessment (> 8 mm outside 7.62 m baseline)

Future Construction Smoothness AT will be moving to IRI using high speed inertial profilers –IRI (International Roughness Index) is a measure based on true road profile –Profilograph Index (PrI) is based on a profile relative to a moving reference –Profile can be collected at highway speeds, increases safety, reduces time, –IRI is already used by AT for P3 projects and PMS

IRI Smoothness Specification Study Study completed in 2009 by EBA Eng. Consultants provided: –Scan of practices and specifications of other agencies using inertial profilers. –Discussion on ProVal software and ability to provide various statistics and indices (IRI, HRI, MRI and Simulated PrI). –Discussion on Half Car IRI (HRI) vs Mean IRI (MRI) indices.

IRI Smoothness Specification Study Study completed in 2009 by EBA Eng. Consultants provided: –Conversion approximations for HRI & MRI vs PrI. –Discussion on assessments based upon discrete segments (100 m) vs continuous segment. –Use of Localized Roughness calculation in ProVal for bump/dip determination.

Current North American Agency Pavement Smoothness Specification by Type (2008)

Simulated Profilograph Index - ProVal

Discrete versus Continuous Segmentation

2009 Comparison Analysis MRI vs PrI Seven paving projects from 2008 were identified that were tested by California Profilograph which had corresponding IRI testing (network level monitoring). A payment assessment schedule for MRI based measurements was modeled after existing PrI tables. Compared bonus/penalty assessment ($) using the MRI vs PrI.

Initial Assessment Schedule Smoothness MeasurementAssessment ($/ 0.1 km) PrI (mm/0.1km)MRI (m/km)Multi Lift (C1) 0 ≤ to to to to to … … to to to to > 23> 1.40Reject

Assessment Comparison $ assessments using MRI criteria was somewhat similar to PrI values. –Six of the seven projects had a net increase in penalties ranging from $10/sublot to $34/sublot. –One project had a net increase in bonus of $12/sublot. –Increased number of reject or “must fix” sublots on six of the projects. Minor tweaking of the Initial Assessment Schedule will result in closer bonus/penalty agreement, however these are two different indexes.