IRI Smoothness Testing for Quality Assurance and Warranty Construction

Alberta Transportation

CUPGA

November 15th, 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 Measurement Assessment ($/ 0.1 km)

PrI (mm/0.1km) MRI (m/km) Multi Lift (C1)

0 ≤ 0.70 30

1 to 10 0.71 to 1.01 0

11 1.02 to 1.04 -40

12 1.05 to 1.07 -70

13 1.08 to 1.10 -100

14 … 20 1.11 ….1.31 -130 to -320

21 1.32 to 1.34 -350

22 1.35 to 1.37 -380

23 1.38 to 1.40 -410

> 23 > 1.40 Reject

Assessment Distribution Comparison for HWY 18:10 Westbound Lane

0

10

20

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40

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70

80

90

100

Assessment ($/ 0.1 km)

Per

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Profilograph

MRI

97 sublotsPrI Net $250

Assessment Distribution Comparison for HWY 18:10 Westbound Lane

0

10

20

30

40

50

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70

80

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100

Assessment ($/ 0.1 km)

Per

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Profilograph

MRI

97 sublotsPrI Net $250MRI Net $1390

Assessment Distribution Comparison for HWY 43:03 Eastbound Lanes

0

10

20

30

40

50

60

70

80

90

100

30 0 -10 -40 -70 -100 -130 -160 -190 -220 Reject

Assessment ($/ 0.1 km)

Per

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Profilograph

174 sublotsPrINet -$540

Assessment Distribution Comparison for HWY 43:03 Eastbound Lanes

0

10

20

30

40

50

60

70

80

90

100

30 0 -10 -40 -70 -100 -130 -160 -190 -220 Reject

Assessment ($/ 0.1 km)

Per

cen

tag

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Profilograph

MRI

174 sublotsPrINet -$540MRINet -$3170

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.