Asphalt Concrete Overlay Design Case Studies

1996 ◽  
Vol 1543 (1) ◽  
pp. 3-9 ◽  
Author(s):  
Linda M. Pierce ◽  
Joe P. Mahoney
Keyword(s):  
Case Studies ◽  
Design Procedure ◽  
Washington State ◽  
Falling Weight Deflectometer ◽  
Department Of Transportation ◽  
Design Procedures ◽  
Overlay Design ◽  
Washington State Department ◽  
Falling Weight ◽  
The University

During the late 1980s, the Washington State Department of Transportation (WSDOT), the University of Washington, and the Washington State Transportation Center developed a mechanistic-empirical flexible overlay design procedure. Following development, WSDOT implemented this overlay design procedure and has been evaluating flexible overlay projects for approximately the past 8 years. WSDOT rehabilitates about 100 projects each year; approximately 20 to 30 percent of the total projects are designed using the WSDOT overlay design procedure and the AASHTO overlay design procedure (using DARWin). These two procedures are discussed in general, and two case studies illustrate each of the overlay design procedures. Also included is the backcalculation of layer moduli from falling weight deflectometer data.

Examination of Washington State Department of Transportation Transfer Functions for Mechanistic-Empirical Asphalt Concrete Overlay Design

1996 ◽  
Vol 1539 (1) ◽  
pp. 25-32
Author(s):  
Joe P. M ahoney ◽  
Linda M. Pierce
Keyword(s):  
South African ◽  
Transfer Functions ◽  
Fatigue Cracking ◽  
State Department ◽  
Washington State ◽  
Pavement Management ◽  
Department Of Transportation ◽  
Overlay Design ◽  
Pavement Testing ◽  
Washington State Department

A review of transfer functions for mechanistic-empirical design procedures is addressed. Specific emphasis is placed on those transfer functions currently used by the Washington State Department of Transportation (WSDOT) and shift factors that relate estimates of laboratory to field fatigue cracking. To achieve this goal, brief discussions about how the WSDOT transfer functions were developed or chosen are presented. A comparison of WSDOT with South African transfer functions is presented. This comparison is of special interest because the South African transfer functions have been updated recently and are in part based on extensive accelerated pavement testing. Finally, mechanistic-empirical overlay designs have been performed by WSDOT for more than 10 years, and a selection of prior overlay projects is reviewed to examine fatigue cracking shift factors. Only projects exhibiting fatigue cracking or its early manifestation are used. The annual visual distress surveys contained in the WSDOT Pavement Management System make this review a bit easier because all pavement sections on the WSDOT route system have been systematically monitored for the preceding 26 years. The conclusion is that the laboratory-based tensile strain relationship currently used by WSDOT must be shifted to predict field fatigue cracking. Such shift factors appear to fall most commonly into a range between 4 and 10.

Mechanistically Based Flexible Overlay Design System for Idaho

1996 ◽  
Vol 1543 (1) ◽  
pp. 10-19 ◽  
Author(s):  
Fouad M. Bayomy ◽  
Fawzi A. Al-Kandari ◽  
Robert M. Smith
Keyword(s):  
Design Procedure ◽  
Failure Criteria ◽  
The State ◽  
Design System ◽  
Falling Weight Deflectometer ◽  
Overlay Design ◽  
Pavement Damage ◽  
Critical Strains ◽  
Falling Weight ◽  
User Friendly

A study was conducted on a mechanistically based overlay design procedure that incorporates the in situ pavement layer modulus values evaluated by deflection-based nondestructive testing using falling weight deflectometer data. The proposed overlay design procedure addresses the seasonal variation in the state of Idaho and adjusts the modulus values accordingly. The performance of the pavement is calculated in terms of critical strains based on the elastic multilayer theory. The study adopts the Asphalt Institute fatigue and rutting failure criteria to calculate the life of the pavement. Damage analysis is performed based on the past and expected future traffic to calculate the required overlay thickness. The procedure developed has been implemented in an event-driven, user-friendly computer program FLEXOLAY, which runs in the DOS environment. The program was tested and compared with other overlay design methods using pavement sections from the state of Idaho. The overlay thickness determined by FLEXOLAY was found to be close to some of the existing methods and far from others, depending on the existing pavement conditions.

Efforts by North Carolina Department of Transportation to Develop Mechanistic Pavement Design System

1996 ◽  
Vol 1539 (1) ◽  
pp. 18-24
Author(s):  
Judith B. Corley-Lay
Keyword(s):  
North Carolina ◽  
First Generation ◽  
Design Procedure ◽  
Pavement Design ◽  
Design System ◽  
Falling Weight Deflectometer ◽  
Department Of Transportation ◽  
North Carolina Department ◽  
Falling Weight ◽  
Repetitions To Failure

A first generation mechanistic empirical pavement design procedure was developed using falling weight deflectometer deflections taken over a 3-year period at 16 test sections in Siler City, North Carolina. Information available for use in developing the procedure included deflection data, surface and air temperature, coring thicknesses at each test location, pavement performance records regarding rate of cracking, and traffic records. Jung's method, based on the curvature of the deflection bowl, was used to calculate strain at the bottom of the asphalt layer as a measure of fatigue. This calculated strain was used to obtain a calculated number of load repetitions to failure. Comparision of actual loads to failure with calculated loads to failure resulted in a table of shift factors by pavement type.

Using Large Linked Field Data Sets to Investigate Density’s Impact on the Performance of Washington State Department of Transportation Asphalt Pavements

2021 ◽  
pp. 036119812110061
Author(s):  
Ryan Howell ◽  
Stephen Muench ◽  
Milad Zokaei Ashtiani ◽  
James Feracor ◽  
Mark Russell ◽  
...  
Keyword(s):  
Aggregate Size ◽  
Large Data ◽  
State Department ◽  
Washington State ◽  
Maximum Aggregate Size ◽  
Test Case ◽  
Data Sets ◽  
Department Of Transportation ◽  
Clear Trend ◽  
Washington State Department

Large data sets of Washington State Department of Transportation (WSDOT) pavement construction and condition data are linked together and used to investigate an implemented change in in-place density to lower specification limit (LSL) from 91% to 92%. This serves as a test case for using such large in-service data sets to create analysis value for a state DOT. Findings include: (1) WSDOT field density has remained relatively steady at 93% for over 20 years; (2) raising the density LSL to 92% will likely result in more contractor effort to achieve higher densities; (3) no clear trend links density with better pavement condition; (4) raising the density LSL will likely result in fewer problematically low densities; and (5) there is no evidence of differing pavement performance based on asphalt content, gradation, or nominal maximum aggregate size.

Direct Method for Evaluating Structural Needs of Flexible Pavements with Falling-Weight Deflectometer Deflections

2003 ◽  
Vol 1860 (1) ◽  
pp. 41-47 ◽  
Author(s):  
Mario S. Hoffman
Keyword(s):  
Direct Method ◽  
Flexible Pavements ◽  
Falling Weight Deflectometer ◽  
Simple Method ◽  
Traffic Demand ◽  
Structural Evaluation ◽  
Overlay Design ◽  
Subgrade Modulus ◽  
Simple Equations ◽  
Falling Weight

A direct and simple method (YONAPAVE) for evaluating the structural needs of flexible pavements is presented. It is based on interpretation of measured falling-weight deflectometer (FWD) deflection basins using mechanistic and practical approaches. YONAPAVE estimates the effective structural number (SN) and the equivalent subgrade modulus independently of the pavement or layer thicknesses. Thus, there is no need to perform boreholes, which are expensive, time-consuming, and disruptive to traffic. Knowledge of the effective SN and the subgrade modulus together with an estimate of the traffic demand allows the determination of the overlay required to accommodate future needs. YONAPAVE’s simple equations can be solved using a pocket calculator, making it suitable for rapid estimates in the field. The simplicity of the method, and its independence from major computer programs, make YONAPAVE suitable for estimating the structural needs of a road network using FWD data collected on a routine or periodic basis along network roads. YONAPAVE can be used with increased experience and confidence as the basis for nondestructive testing structural evaluation and overlay design at the project level.

Flexible Pavement Overlays: The State Experience

1997 ◽  
Vol 1568 (1) ◽  
pp. 139-147
Author(s):  
Peter E. Sebaaly ◽  
Stephen Lani ◽  
Sohila Bemanian ◽  
Christopher Cocking
Keyword(s):  
Design Method ◽  
Design Procedure ◽  
Survey Method ◽  
Department Of Transportation ◽  
Significant Discrepancy ◽  
Design Engineers ◽  
Routine Basis ◽  
Final Design ◽  
Overlay Design ◽  
Nondestructive Testing Method

The design and construction of flexible overlays has become a popular exercise. However, there is not a simple, straightforward, and yet reliable design procedure that the design engineer can implement on a routine basis. The data needed for overlay design are not easily accessible to the design engineer, and yet the accessible data are not fully reliable in most cases. The process by which the design engineers at the Nevada Department of Transportation handle overlay design is presented. The various steps followed and the obstacles that the design engineer encounters in the search for the necessary data and the final design process are described. Major assumptions must be made along the way that could significantly affect the final design. Three case studies are presented. Each project was designed using three different design methods, including the AASHTO nondestructive testing method, the AASHTO condition survey method, and the Nevada Department of Transportation (NDOT) mechanistic overlay design method. All three methods used the same data gathered by the design engineer for each project. The analysis indicates that there is a significant discrepancy between the two AASHTO methods, whereas the NDOT method and the AASHTO condition survey method agreed on one project.

Calibration of NCHRP 1–37A Software for the Washington State Department of Transportation

2006 ◽  
Vol 1949 (1) ◽  
pp. 43-53 ◽  
Author(s):  
Jianhua Li ◽  
Stephen T. Muench ◽  
Joe P. Mahoney ◽  
Nadarajah Sivaneswaran ◽  
Linda M. Pierce
Keyword(s):  
State Department ◽  
Washington State ◽  
Department Of Transportation ◽  
Washington State Department

Parks Highway Load Restriction Field Data Analysis: Case Study

1998 ◽  
Vol 1615 (1) ◽  
pp. 32-40 ◽  
Author(s):  
Lutfi Raad ◽  
Eric Johnson ◽  
Dave Bush ◽  
Stephan Saboundjian
Keyword(s):  
Field Data ◽  
Traffic Data ◽  
Falling Weight Deflectometer ◽  
Department Of Transportation ◽  
Truck Traffic ◽  
Weigh In Motion ◽  
Pavement Damage ◽  
Field Data Analysis ◽  
Falling Weight ◽  
Thaw Period

The loss of pavement strength during spring thaw could result in excessive road damage under applied traffic loads. Damage assessment associated with the critical thaw period is essential to evaluate current load restriction policies. The Alaska Department of Transportation and Public Facilities proposed a plan that will provide an engineering analysis of field conditions with 100-percent loads on the Parks Highway for 1996. Extensive data were collected and analyzed in an effort to monitor pavement damage during the spring of 1996 and to determine loss of pavement strength. Field data included truck traffic data from scalehouse and weigh-in-motion (WIM) stations, pavement temperature data, profilometer data for roughness and rutting, and falling weight deflectometer data. Analyses were performed to compare WIM and scalehouse traffic data and to determine the fraction of overweight axle-loads and corresponding pavement damage during spring thaw. Northbound and southbound truck traffic and its effect on pavement damage were considered. Ground temperature measurements were analyzed to determine when thaw initiates and how long seasonal load restrictions are required. In addition, comparisons of remaining life with and without load restrictions using mechanistic methods were conducted.

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