David R Luhr

Structured Approach to Managing Quality of Pavement Distress Data: Virginia Department of Transportation Experience

The Virginia Department of Transportation (VDOT) Pavement Management Program has examined and improved the quality of condition data to carry out pavement performance analysis and multiyear work planning. In 1995 the agency changed the way it gathered pavement condition data, moving from subjective windshield surveys to using automated condition survey equipment. In 1997 the agency acquired the staff and resources to examine these data and respond to concerns of district personnel that the data were inconsistent and not representative of actual conditions. At that time, VDOT acknowledged the need for a formal and large-scale quality assurance program for its pavement condition data. It was shown in 1998 that standardization of test methods and calibration of equipment for roughness measurement yielded data of much higher quality than that in previous years. Quality data are crucial to the sound functioning of a pavement management system. It has been found that (a) distress data quality is a serious problem and the data can potentially be bad enough to be completely useless and (b) improving or reengineering distress data quality requires a significant effort. A structured approach to develop and implement a pavement distress data quality program at VDOT is described, including the processes, statistical details, and a clear vision of needs. Most important, this reengineering effort involves attending to the data collection process by building controls at critical junctures during the project in order to deliver a quality data product in time and on budget.

Pavement Performance Modeling Using Piecewise Approximation

A successful pavement management system requires an accurate pavement performance prediction model. A novel pavement performance model using the piecewise approximation approach was developed to estimate the pavement serviceable life. It can be broadly applied to estimate pavement performance of any distress types or indexes. The basic theory of the piecewise approximation is to divide the whole pavement serviceable life into three zones: Zone 1 for early age pavement distress, Zone 2 in rehabilitation stage, and Zone 3 for overdistressed situations. Historical pavement performance data are regressed independently in each time zone. This approach can accurately predict pavement distress progression trends in each individual zone by eliminating possible impacts from biased data in other zones. This paper describes the theoretical piecewise approximation process of data classification and model regression and then demonstrates an implementation for a group of Washington State Department of Transportation asphalt concrete pavements. The results are compared with the Mechanistic–Empirical Pavement Design Guide incremental damage approach, the current Washington State Pavement Management System (WSPMS) exponential model, and ordinary regression on all data points. Results indicate that the proposed approach is able to estimate the most accurate rehabilitation due year and to predict the performance trends for each divided zone. The piecewise approximation approach is planned for implementation into the WSPMS and will play an important role in decision making for future pavement rehabilitations.

Preservation Strategies for Concrete Pavement Network of Washington State Department of Transportation

The Washington State Department of Transportation (DOT) has about 2,400 lane miles of mainline concrete pavements. The pavements have far exceeded their design lives and have carried several times the estimated traffic loading. Initial Washington State DOT estimates place the cost of reconstructing and rehabilitating the concrete pavement network in the next 10 years at approximately

Pavement Preservation Funding and Performance in Washington State

1.1 billion. However, as for most DOTs, Washington States roadway preservation budget has been reduced. Maintaining a good performance level with reduced funding requires innovative techniques and the best investment choices. A preservation strategy was developed for the Washington State DOTs concrete pavement network to allow delay or avoidance of capital construction spending. The strategy accounts for current pavement conditions, predicted future conditions, and financial constraints. The DOTs pavements division uses a detailed four-step process to select the proper preservation methods for a project: (a) monitor the current concrete pavement performance annually, (b) use updated indices to evaluate pavement conditions, (c) scope the rehabilitation needs by the least life-cycle cost, and (d) propose preservation strategies within various scenarios of constrained funding. The states pavement management system provides a framework for evaluating and monitoring the performance of the Washington State DOTs roadway investments.

Modeling and Analyzing Budget-Constrained Pavement Preservation Strategies

The Washington State Department of Transportation (WSDOT) maintains more than 18,000 lane miles of state highway pavement, consisting of three pavement surface types: hot-mix asphalt, bituminous surface treatment (or chip seal), and portland cement concrete pavement. WSDOT has by legislative direction in state law maintained a specific budget item within the agencys capital budget for pavement preservation. Although these funds have not kept pace with inflation and are subject to other transportation spending priorities, such as maintenance, traffic operations, safety, congestion relief, and environmental retrofit, the end result is encouraging. But challenges loom. That point is illustrated by examination of what funds were spent by biennium and pavement type. This is followed by an overview of the current condition and performance of the state-managed pavements and where there are growing needs. A combined view of expenditures and performance suggests that the WSDOT process works reasonably well.

Cost-Effective Performance Management for Washington State Pavement Assets

The Washington State pavement management system (WSPMS) has a long and well-known history of describing network condition, predicting necessary rehabilitation, and guiding the Washington State Department of Transportation (DOT) to the best possible value for pavements meeting an acceptable level of service. By definition, lowest life-cycle cost (LLCC) is the most economical way to manage roadways to a required level of service. What does an agency do when it is currently, and projected to be, funded at less than half of what LLCC calculations recommend? This deceptively difficult question reflects the situation that the Washington State DOT currently faces with its preservation budget. To assist the agency in answering this question, the WSPMS developed a tool called the Forecaster, allowing definition of a forecast scenario that enables the user to define a yearly budget with optional allocations, preservation techniques, prioritization of roadways and activities, and more, and analyzes the results of the forecast by using several different performance measures. Presented are an overview of the new WSPMS tool to create forecasts, a general overview of the forecast process, and the performance measures that the WSPMS gives to users to analyze the results of a forecast. Finally, several funding scenarios are compared by the expected performance measure outcomes, and a specific prioritization methodology is recommended for the severely constrained preservation budget of the Washington State DOT.

What we don’t know about pavement preservation

The Washington State Department of Transportation (DOT) manages 18,230 lane miles (29,332 lane kilometers) of main-line roadway. In the past several years, the Washington State DOT has gone through an evaluation and modification of its pavement management practices. This paper presents the historical perspective on past Washington State DOT pavement practices and several strategies that were developed to improve the management of pavement assets. The Washington State DOT has been successfully preserving the long life of flexible pavements by applying thin hot-mix asphalt (HMA) mill and inlays on the basis of the concept that cracking in thicker HMA sections will primarily be top-down. Furthermore, using the framework developed by the evaluation of cost-effectiveness, several strategies have been implemented to improve the management of Washington State DOT pavement assets. These strategies are (a) converting 3,000 lane miles (4,827 km) from asphalt to chip seal resurfacing before the year 2025, (b) planning

STRUCTURAL ANALYSIS OF AASHO ROAD TEST FLEXIBLE PAVEMENTS FOR PERFORMANCE EVALUATION

850 million to

SENSITIVITY ANALYSIS OF PREDICTED PAVEMENT PERFORMANCE

1.0 billion for rehabilitation and reconstruction for the aging concrete pavement network for the next 10 years with 50% of the concrete slated for reconstruction to be converted to flexible pavement using a crack and seat plus asphalt overlay process, and (c) applying strategic maintenance to reduce the annual cost by extending the service life of flexible pavements. These cost-effective strategies are expected to generate an overall annual cost savings of

SIMPLIFIED RATIONAL PAVEMENT DESIGN PROCEDURE FOR LOW-VOLUME ROADS

80 million per year by 2025.