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Project Details
STATUS

In-Progress

START DATE

06/29/17

END DATE

12/31/20

FOCUS AREAS

Infrastructure

RESEARCH CENTERS InTrans, AMPP
SPONSORS

Oregon Department of Transportation

Researchers
Principal Investigator
Ashley Buss

Faculty Affiliate

About the research

The first objective of the Phase II research is to facilitate implementation of the new chip seal design and accompanying performance specifications. In addition, there is a strong need to verify the design developed in Phase I. The primary objective of Phase II is to collaborate with the Oregon Department of Transportation to implement the findings of the new chip seal design methodology and performance specification by providing training and education. The second objective is to leverage the initial research investment to enhance the documentation of the chip seal performance tests sections and to verify that preliminary estimates developed using the design criteria are similar to actual field application rates.

Project Details
STATUS

In-Progress

START DATE

10/01/14

END DATE

06/30/16

RESEARCH CENTERS InTrans, CTRE
SPONSORS

Oregon Department of Transportation

PARTNERS

sub to Northern Arizona University

Researchers
Principal Investigator
Anuj Sharma

Research Scientist and Leader, REACTOR

About the research

This research will develop a realistic installation guideline that supports the requirements of advance traffic signal controller operations, hybrid detection installations, and non-invasive detection optimization. This guideline shall provide prototypical detection configurations and new timing standards with the goal of reducing or eliminating performance degradation. These guidelines will include a cost analysis that appropriately considers equipment and installation costs as well as the cost of increase delay to the motoring public due to the degradation of signal performance. The costs of this delay can be as much as ($18 per delay hour per/day per passenger vehicle) and as much as ($70 per delay hour per/day per interstate transit vehicle).

Subcontractor to Northern Arizona University on this project.

Project Details
STATUS

Completed

START DATE

06/28/11

END DATE

09/30/14

RESEARCH CENTERS InTrans, CTRE
SPONSORS

Federal Highway Administration State Planning and Research Funding
Oregon Department of Transportation

Researchers
Principal Investigator
Chris Williams

Director, AMPP

About the research

Recently, the Oregon Department of Transportation (ODOT) has identified hot mix asphalt concrete (HMAC) pavements that have displayed top-down cracking within three years of construction. The objective of the study was to evaluate the top-down cracked pavement sections and compare the results with the non-cracked pavement sections. Research involved evaluating six surface cracked pavements and four non-cracked pavement sections. The research included extensive field and laboratory investigations of the 10 pavement sections by conducting distress surveys, falling weight deflectometer (FWD) testing, dynamic cone penetrometer (DCP) testing, and coring from the cracked and non-cracked pavement sections. Cores were then subjected to a full laboratory-testing program to evaluate the HMAC mixtures and binder rheology. The laboratory investigation included dynamic modulus, indirect tensile (IDT) strength, and specific gravity testing on the HMAC cores, binder rheological tests on asphalt binder and aggregate gradation analysis. The FWD and DCP tests indicated that top-down cracked pavement sections were structurally sound, even some of the sections with top-down cracking showed better structural capacity compared to non-cracked sections. The study also found that top-down cracking initiation and propagation were independent of pavement cross-section or the HMAC thickness. The dynamic modulus testing indicated that cores from all the t op-down cracked pavement sections except one section (OR 140) possessed stiffer mixtures than that of non-cracked pavement sections. All four non-cracked pavement areas were found to be exhibiting fairly high IDT strength, and low variability in IDT strength and HMAC density when compared to top-down cracked sections as indicated by the IDT strength tests and air void analysis. Asphalt binder rheological test result indicated that asphalt binders from all the top-down cracked sections except OR140 showed higher complex shear modulus (stiffer binder) compared to non-cracked pavement sections. The study concluded that top-down cracking could be caused by a number of contributors such as stiffer HMAC mixtures, mixture segregation, binder aging, low HMAC tensile strength, and high variability in tensile strength or by combination of any.

Project Details
STATUS

Completed

START DATE

01/25/10

END DATE

09/30/14

FOCUS AREAS

Infrastructure

RESEARCH CENTERS InTrans, CTRE
SPONSORS

Federal Highway Administration State Planning and Research Funding
Oregon Department of Transportation

Researchers
Principal Investigator
Chris Williams

Director, AMPP

About the research

The Oregon Department of Transportation (ODOT) is in the process of implementing the recently introduced AASHTO Mechanistic-Empirical Pavement Design Guide (MEPDG) for new pavement sections. The majority of pavement work conducted by ODOT involves rehabilitation of existing pavements. Hot mix asphalt (HMA) overlays are preferred for both flexible and rigid pavements. However, HMA overlays are susceptible to fatigue cracking (alligator and longitudinal cracking), rutting, and thermal cracking. This study conducted work to calibrate the design process for rehabilitation of existing pavement structures. Forty-four pavement sections throughout Oregon were included. A detailed comparison of predictive and measured distresses was made using MEPDG software Darwin M-E (Version 1.1). It was found that Darwin M-E predictive distresses did not accurately reflect measured distresses, calling for a local calibration of performance prediction models. Darwin M-E over predicted total rutting compared to the measured total rutting and most of the rutting predicted by Darwin M-E occurs in the subgrade. For alligator (bottom-up) and thermal cracking, Darwin M-E underestimated the amount of cracking considerably as compared to in-field measurements. A high amount of variability between predicted and measured values was observed for longitudinal (top-down) cracking. The performance (punch-out) model was also assessed for continuously reinforced concrete pavement (CRCP) using Darwin M-E’s default (nationally calibrated) coefficients.

Four distress prediction models (rutting, alligator, longitudinal, and thermal cracking) of the HMA overlays were calibrated for Oregon conditions. It was found that the locally calibrated models for rutting, alligator, and longitudinal cracking provided better predictions with lower bias and standard error than the nationally (default) calibrated models. However, there was a high degree of variability between the predicted and measured distresses, especially for longitudinal and transverse cracking, even after the calibration. It is believed that there is a significant lack-of-fit modeling error for the occurrence of longitudinal cracks. The Darwin M-E calibrated models of rutting and alligator cracking can be implemented, however, it is recommended that additional sites be established and included in the future calibration efforts to improve the accuracy of the prediction models.

 

Project Details
STATUS

Completed

PROJECT NUMBER

Oregon DOT SPR 777

START DATE

07/18/14

END DATE

12/30/16

FOCUS AREAS

Infrastructure

RESEARCH CENTERS InTrans, AMPP, CTRE
SPONSORS

Federal Highway Administration State Planning and Research Funding
Oregon Department of Transportation

Researchers
Principal Investigator
Ashley Buss

Faculty Affiliate

Co-Principal Investigator
Chris Williams

Director, AMPP

Co-Principal Investigator
Doug Gransberg

Affiliate Researcher

About the research

Chip seals or seal coats, are a pavement preservation method constructed using a layer of asphalt binder that is covered by a uniformly graded aggregate. The benefits of chip seal include: sealing surface cracks, keeping water from penetrating the surface, provides an anti-glare surface, minimizes the effect of aging as it seals the pavement surface, provides a highly skid-resistant surface, and is cost effective.

This study summarizes performance and the methodology used for developing specifications and a rational chip seal design in Oregon. Test sections included both emulsified asphalt and hot-applied chip seal applications. The pre- and post-construction pavement performance information is presented and analyzed. Post-construction analysis of the chip seals includes macrotexture analysis, dynamic friction testing to measure microtexture, and pavement performance surveys. The underlying pavement conditions were classified from being very good to very poor performance. In this study, a comparison of field performance on test section is developed to recommend best practices and develop a rational design methodology. A comparative study between the application of McLeod method and New Zealand method is performed to evaluate the best chip seal design methodology for adoption into the State chip seal specifications. The results will also determine if the macro-texture based New Zealand chip seal performance specification is applicable for Oregon chip seals.

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