Development of IDOT’s Proposed Smoothness Specification Based on the International Roughness Index

Lee, Hyung S.; Vavrik, William; Abdualla, Hesham

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https://hdl.handle.net/2142/108372 Copy

Description

Title

Development of IDOT’s Proposed Smoothness Specification Based on the International Roughness Index

Author(s)

• Lee, Hyung S.
• Vavrik, William
• Abdualla, Hesham

Issue Date

2020-09

Keyword(s)

• Smoothness
• International Roughness Index
• Incentive
• Specification

Abstract

The existing smoothness specification implemented by the Illinois Department of Transportation (IDOT) was based on profile-index measurement, which was also widely used by other agencies. There is a national and international trend, however, toward using the international roughness index (IRI) as a standard smoothness index for pavement management as well as construction acceptance. Therefore, the primary objective of this study was to develop an IRI-based smoothness specification for IDOT. It was desired that IRI thresholds be developed objectively by quantifying the benefit of pavement smoothness. The benefits quantified within the framework of life cycle cost analysis and benefit-cost analysis generally revealed that smoother pavements are anticipated to exhibit increased service life, reduced life cycle cost (including agency and user costs), and improved safety. IRI is also a crucial component of user comfort, especially for high-speed facilities. IDOT’s new IRI-based specification was developed while considering these benefits along with the increased cost quantified as the incentive payments to be made for smoother pavements. In addition, several aspects of IRI thresholds and the smoothness assessment schedule were investigated for achievability and risk. Although the risk of moving from a profile-index-based specification to an IRI-based specification was found to be relatively low (i.e., 4.4% and 6.6% risk assessed for high-speed and low-speed facilities, respectively), it indicated that IDOT and IDOT’s contractors may need to work together to adapt to the new specification and continue to refine the IRI-based specification as more experience is gained.

Publisher

Illinois Center for Transportation/Illinois Department of Transportation

Series/Report Name or Number

FHWA-ICT-20-009

ISSN

0197-9191

Type of Resource

text

Language

en

Permalink

http://hdl.handle.net/2142/108372

DOI

https://doi.org/10.36501/0197-9191/20-015

Sponsor(s)/Grant Number(s)

IDOT-R27-199

Copyright and License Information

No restrictions. This document is available through the National Technical Information Service, Springfield, VA 22161.

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