Development of Canadian asphalt pavement deterioration models to benchmark performance

2003 ◽  
Vol 30 (4) ◽  
pp. 637-643 ◽  
Author(s):  
Chris Raymond ◽  
Susan Tighe ◽  
Ralph Haas ◽  
Leo Rothenburg
Keyword(s):  
Univariate Analysis ◽  
Pavement Performance ◽  
Site Location ◽  
Site Factors ◽  
Asphalt Overlay ◽  
Pavement Roughness ◽  
Pavement Deterioration ◽  
Individual Project ◽  
Asphalt Overlays

The Canadian Long Term Pavement Performance (C-LTPP) study, initiated in 1989, involves 65 sections located at 24 sites constructed with various asphalt overlay rehabilitation treatments. This study investigates the impacts of the various alternative rehabilitation treatments on pavement roughness progression. A series of models are developed for predicting the rate of pavement deterioration occurring for the first 8 years of service. The models examine both within-site factors and between-site factors. Site location is found to be the primary influence on the rate of pavement deterioration. Overlay thickness and the amount of cracking prior to rehabilitation are also determined to influence pavement deterioration at a strong statistical level. Models are provided for benchmarking the performance of pavements across Canada, for comparison with individual project designs, and for estimating the performance of designs with different overlay thickness.Key words: Canadian Long Term Pavement Performance program, roughness, pavement deterioration, site effects, asphalt overlays, benchmark, univariate analysis.

Evaluation of subgrade and climatic zone influences on pavement performance in the Canadian Strategic Highway Program's (C-SHRP) Long-Term Pavement Performance (LTPP) study

2002 ◽  
Vol 39 (2) ◽  
pp. 377-387 ◽  
Author(s):  
Susan Tighe
Keyword(s):  
Climatic Factors ◽  
Pavement Performance ◽  
Valuable Insight ◽  
Pavement Rehabilitation ◽  
Traffic Loading ◽  
Subgrade Soils ◽  
Pavement Roughness ◽  
Subgrade Soil ◽  
Asphalt Overlays

Sixty-five sections in 24 provincial test sites received pavement rehabilitation comprising of various thicknesses of asphalt overlays, as part of the Canadian Long-Term Pavement Performance (C-LTPP) study, which was initiated in 1989. This paper describes the impacts of the various alternative rehabilitation treatments on pavement performance in terms of roughness progression under comparative climatic, subgrade soil, and traffic loading conditions. Some findings from this study include (i) in wet, high-freeze zones, thinner overlays show a higher rate of roughness progression than thicker overlays, regardless of subgrade type; (ii) in dry, high-freeze zones, roughness progression for medium and thick overlays is relatively small; (iii) in wet, low-freeze zones, thinner overlays combined with fine subgrade soils show the highest rate of roughness progression; and (iv) traffic, in terms of equivalent single axle loads (ESALs), seemed to have a limited effect on all of the above; this was attributed largely to the fact that all of the traffic essentially fell into one level, where 200 000 ESALs per year was designated as the boundary between low and high traffic levels. The methodology developed in this paper provides valuable insight into how subgrade and climatic factors influence pavement performance and can be applied to performance trend analysis of other pavements with similar climatic, subgrade, and traffic loading conditions.Key words: subgrade type, climatic zones, pavement roughness, international roughness index (IRI), Long-Term Pavement Performance (LTPP).

Determining the Age and Smoothness of Asphalt and Concrete Pavements at the Time of First Rehabilitation using Long-Term Pavement Performance Program Data

2018 ◽  
Vol 2672 (40) ◽  
pp. 176-185 ◽  
Author(s):  
Mary Robbins ◽  
Nam Tran ◽  
Audrey Copeland
Keyword(s):  
Life Cycle Cost ◽  
Evaluation Process ◽  
Concrete Pavement ◽  
Asphalt Pavements ◽  
Pavement Performance ◽  
Concrete Pavements ◽  
Pavement Roughness ◽  
And Performance ◽  
Program Data

Initial performance period is an important input in life-cycle cost analysis (LCCA). An objective of this study was thus to determine actual initial performance periods, as the pavement age at first rehabilitation, for asphalt and concrete pavements using Long-Term Pavement Performance (LTPP) program data. In addition, most agencies use International Roughness Index (IRI), a measure of pavement roughness applicable to both asphalt and concrete pavements, in their decision-making and performance-evaluation process. A secondary objective was, therefore, to determine the pavement roughness condition at the time of first rehabilitation using the same dataset. Based on surveys of highway agencies, initial performance periods frequently used in LCCA for asphalt pavements are between 10 and 15 years, while the average asphalt pavement age at time of first rehabilitation in the LTPP program was found to be approximately 18 years. For concrete pavements, most initial performance periods used in LCCA are between 20 and 25 years, whereas the average concrete pavement age at the time of first rehabilitation in the LTPP program is about 24 years. This suggests initial performance period values used for LCCA do not adequately represent the actual age of asphalt pavements at the time of first rehabilitation, while they are generally representative of actual concrete pavement age at the time of first rehabilitation. Also, it was found that asphalt pavements are typically rehabilitated when they are in good or fair condition according to Federal Highway Administration (FHWA) IRI criteria whereas concrete pavements are typically not rehabilitated until the pavement is in fair or poor condition.

Performance of Flexible Pavement Rehabilitation Treatments in the Long-Term Pavement Performance SPS-5 Experiment

2003 ◽  
Vol 1823 (1) ◽  
pp. 93-101 ◽  
Author(s):  
Kathleen T. Hall ◽  
Carlos E. Correa ◽  
Amy L. Simpson
Keyword(s):  
Asphalt Pavement ◽  
Fatigue Cracking ◽  
Flexible Pavement ◽  
Asphalt Pavements ◽  
Pavement Performance ◽  
Recycled Asphalt ◽  
Pavement Rehabilitation ◽  
Pretreatment Condition ◽  
Asphalt Overlay

The results of a study conducted to assess the relative performance of different flexible pavement rehabilitation treatments, including the influence of pretreatment condition and other factors, are presented. The data used in the study were drawn from the Long-Term Pavement Performance Studies' Specific Pavement Study (SPS) SPS-5 and General Pavement Study (GPS) GPS-6B experiments. The rehabilitation treatments used in the SPS-5 experiment are 2- and 5-in. overlays with virgin or recycled asphalt concrete mixes with or without preoverlay milling. Overlay thickness and preoverlay roughness levels were the two factors that most influenced the performance of the asphalt overlays of asphalt pavements in the SPS-5 experiment with respect to roughness, rutting, and fatigue cracking. Over the long term, the 5-in. overlays outperformed the 2-in. overlays with respect to roughness, rutting, and fatigue cracking. Overlay mix type (virgin versus recycled) and preoverlay preparation (with or without milling) had slight and inconsistent effects. The average initial postoverlay international roughness index of an asphalt overlay of an asphalt pavement was found to be 0.98 m/km. The data show a slight but statistically significant tendency for asphalt pavements overlaid when they were rougher to have more initial roughness after overlay than asphalt pavements overlaid when they were smoother. The data show that, on average, about 6 mm of rutting develops in the first year or so after placement of an asphalt overlay of an asphalt pavement. This is presumably due to compaction of the mix by traffic and appears to be independent of the overlay thickness, mix type, preoverlay preparation, and preoverlay rutting level.

Performance of Rigid Pavement Rehabilitation Treatments in the Long-Term Pavement Performance SPS-6 Experiment

2003 ◽  
Vol 1823 (1) ◽  
pp. 64-72 ◽  
Author(s):  
Kathleen T. Hall ◽  
Carlos E. Correa ◽  
Amy L. Simpson
Keyword(s):  
Performance Studies ◽  
Concrete Pavement ◽  
Pavement Performance ◽  
International Roughness Index ◽  
Rigid Pavement ◽  
Pavement Rehabilitation ◽  
Pretreatment Condition ◽  
Diamond Grinding ◽  
Asphalt Overlays

The results of a study conducted to assess the relative performance of different jointed rigid pavement rehabilitation treatments, including the influence of pretreatment condition and other factors, are presented. The data used in the study were drawn from the Long-Term Pavement Performance Studies' Specific Pavement Study (SPS) SPS-6 and General Pavement Study (GPS) GPS-7B experiments. The rehabilitation treatments used in the SPS-6 experiment were minimal and intensive nonoverlay repair, 4-in. asphalt overlays with minimal and intensive preoverlay preparation, 4-in. overlays with sawed and sealed joints, and 4- and 8-in. asphalt overlays of cracked and seated concrete slabs. Overall, the rigid pavement rehabilitation treatments in the SPS-6 experiment could be ranked from most to least effective in the following order: 8-in. overlay of cracked or broken and seated pavement, 4-in. overlay (of either intact or cracked or broken and seated pavement, with or without sawing and sealing of joints and with either minimal or intensive preoverlay repair), concrete pavement restoration with diamond grinding, and concrete pavement restoration without diamond grinding. Concrete pavement restoration with diamond grinding yielded an initial posttreatment international roughness index (IRI) of 1.05 m/km, on average, whereas restoration without diamond grinding yielded no benefit in IRI and in fact tended to leave the pavement rougher than before. In the long term, both restoration and overlay treatments reduced long-term roughness, rutting, and cracking levels compared with those on the control sections, but the conditions of the restored test sections are approaching those of the control sections faster than those of the overlay sections.

Deterioration of Asphalt Pavement at Long-Term Pavement Performance Program Site 49-1001 in Utah

2005 ◽  
Vol 1933 (1) ◽  
pp. 121-125
Author(s):  
Brandon J. Blankenagel ◽  
W. Spencer Guthrie
Keyword(s):  
Base Layer ◽  
Pavement Performance ◽  
Falling Weight Deflectometer ◽  
Water Drainage ◽  
Base Materials ◽  
Pavement Deterioration ◽  
Pavement Base ◽  
Aggregate Base ◽  
Falling Weight

Highway 191 near Bluff, Utah, features a well-monitored section of the long-term pavement performance (LTPP) program. Constructed in 1980, this section of flexible pavement performed well for nearly 13 years. Through this time, cracking of the asphalt layer was minimal. In the fourteenth year, however, the extent of longitudinal cracking in the wheel path increased and necessitated placement of a chip seal on the pavement surface. The purpose of this research was to determine the cause of pavement deterioration using LTPP data. Deflection basins obtained from falling-weight deflectometer testing were analyzed to investigate the extent to which structural degradation influenced deterioration of the pavement. Pavement layer modulus values were plotted against time and clearly show that weakening of the pavement base layer immediately preceded the occurrence of cracking. The geography of the site, as documented in photographs, supports the conclusion that inadequate water drainage at the site permitted saturation of the aggregate base layer during a period of midsummer flooding. This finding emphasizes the importance of specifying non-moisture-susceptible base materials and providing necessary drainage works in pavement design.

Evaluation of Long-Term Pavement Performance Data Using HDM-III Probabilistic Failure-Time Models for Crack Initiation in Bituminous Pavements

1997 ◽  
Vol 1592 (1) ◽  
pp. 125-133 ◽  
Author(s):  
Thomas J. Van Dam ◽  
Andrew D. Chesher ◽  
David G. Peshkin
Keyword(s):  
Crack Initiation ◽  
Failure Time ◽  
Climatic Factors ◽  
Pavement Performance ◽  
General Applicability ◽  
Highway Design ◽  
Depth Analysis ◽  
Pavement Deterioration ◽  
Bituminous Pavements

Cracking is perhaps the most important distress in bituminous pavements. It plays a key role in modeling bituminous pavement performance in the World Bank’s Highway Design and Maintenance Standards Model Version III (HDM-III) with the belief that a cracked pavement is susceptible to moisture ingress, which accelerates pavement deterioration. Strategic Highway Research Program Long-Term Pavement Performance (LTPP) data were analyzed by using the probabilistic failure-time crack initiation models previously developed for use in HDM-III. On the basis of that analysis, it is concluded that the HDM-III models do not accurately capture the climatic factors that play a role in linear cracking initiation typically observed in North America. When considering only fatigue-related cracking, HDM-III models could be successfully fit to the data, but concerns related to the shape parameter call into question their general applicability. It is concluded that although some aspects of this analysis suggest that HDM-III models adequately model fatigue-related crack initiation in LTPP pavement sections, overall the results are inconclusive and a more in-depth analysis needs to be conducted.

Incorporating Variability into Pavement Performance, Life-Cycle Cost Analysis, and Performance-Based Specification Pay Factors

2005 ◽  
Vol 1940 (1) ◽  
pp. 13-20 ◽  
Author(s):  
Leanne Whiteley ◽  
Susan Tighe ◽  
Zhanmin Zhang
Keyword(s):  
Life Cycle ◽  
Service Life ◽  
Cost Analysis ◽  
Life Cycle Cost ◽  
Service Performance ◽  
Pavement Performance ◽  
Life Cycle Cost Analysis ◽  
Asphalt Overlay ◽  
Design Life

This paper describes a recent research study that examined how changes in design life affected the pavement life-cycle cost and ultimately how the reduction in or addition to life-cycle cost attributed to superior or inferior in-service performance could be used as a basis for establishing a pay factor for a performance-based specification. Previous models were developed with data from the Canadian Long-Term Pavement Performance Program, which indicated that overlay thickness, total prior cracking, annual freezing index, annual days with precipitation, and accumulated equivalent single-axle loads (ESALs) after 8 years affected the slope of pavement deterioration for asphalt overlay pavements. One of these models, as well as data from the U.S. Long-Term Pavement Performance test sites, is used to determine the service life of asphalt overlay pavements. This paper examines how the variability associated with overlay thickness, total prior cracking, and accumulated ESALs after 8 years affects the service life of asphalt overlay pavements. Furthermore, this paper considers the variability associated with the discount rate and incorporates all associated variability into the life-cycle cost analysis (LCCA). LCCA is performed by using Monte Carlo techniques. On the basis of a recent study, distributions for service life and life-cycle costs are developed by using both normal and lognormal distributions for overlay thickness. With the LCCA values for typical design lives, a sensitivity analysis is subsequently performed to evaluate the impact of 10%, 20%, and 30% differences in the in-service performance as compared to the design life. These LCCA differences are then used as a basis for establishing pay factors. Overall the paper attempts to relate design to in-service performance life-cycle cost and the ultimate use of pay factors.

scholarly journals Clinical outcome of endoscopic therapy in patients with symptomatic pancreas divisum: a Dutch cohort study

2021 ◽  
Vol 09 (07) ◽  
pp. E1164-E1170
Author(s):  
David M. de Jong ◽  
Pauline M. Stassen ◽  
Jan Werner Poley ◽  
Paul Fockens ◽  
Robin Timmer ◽  
...  
Keyword(s):  
Acute Pancreatitis ◽  
Cohort Study ◽  
Endoscopic Therapy ◽  
Clinical Success ◽  
Pancreas Divisum ◽  
Univariate Analysis ◽  
Clinical Success Rate ◽  
Recurrent Acute Pancreatitis ◽  
Pancréas Divisum

Abstract Background and study aims Although the majority of patients with pancreas divisum (PDiv) are asymptomatic, a subgroup present with recurrent pancreatitis or pain for which endoscopic therapy may be indicated. The aim of this study was to evaluate success rates and long-term outcomes of endoscopic treatment in patients with symptomatic PDiv. Patients and methods A multicenter, retrospective cohort study was performed. Patients with symptomatic PDiv presenting with recurrent acute pancreatitis (RAP), chronic pancreatitis (CP), or chronic abdominal pancreatic-type pain (CAP) who underwent endoscopic retrograde cholangiopancreatography (ERCP) between January 2000 and December 2019 were included. The primary outcome was clinical success, defined as either no recurrent episode of acute pancreatitis (AP) for RAP patients, no flares for CP patients, or absence of abdominal pain for patients with CAP after technically successful ERCP. Results In 60 of 81 patients (74.1 %) a technically successful papilla minor intervention was performed. Adverse events were reported in 30 patients (37 %), with post-ERCP pancreatitis in 18 patients. The clinical success rate for patients with at least 3 months of follow-up was 42.6 %, with higher rates of success among patients presenting with RAP (44.4 %) as compared to those with CP (33.3 %) or CAP (33.3 %). Long-term sustained response was present in 40.9 % of patients with a technically successful intervention. In patients with RAP who did not completely respond to treatment, the mean number of AP episodes after treatment decreased significantly from 3.5 to 1.1 per year, and subsequently the interval between AP episodes increased from 278 to 690 days (P = 0.0006). A potential predictive factor of failure of clinical success after technically successful ERCP, at univariate analysis, was male sex (OR = 0.25, P = 0.02). Conclusions Endoscopic therapy in patients with symptomatic PDiv is moderately effective, with its highest yield in patients presenting with RAP. Future studies are needed to assess factors predictive for success of endoscopic therapy and potential risk factors for relapse after ERCP.

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