Guidelines for Informing Decisionmaking to Affect Pavement Performance Measures: Final Report

CHAPTER 1. INTRODUCTION

Background

The Moving Ahead for Progress in the 21^st Century Act (MAP-21) legislation required that performance measures be established for the Interstate Highway System (IHS).⁽¹⁾ It also required that State departments of transportation (DOTs) develop and implement a risk- and performance-based Transportation Asset Management Plan covering the pavements and bridges within the National Highway System (NHS), as a minimum.

In January 2017, the Federal Highway Administration (FHWA) issued the Final Rule (effective February 17, 2017) to implement the performance management requirements of MAP-21 and the Fixing America’s Surface Transportation Act.⁽²⁾ The Final Rule established four pavement performance measures to assess pavement condition as follows:⁽³⁾

• Percentage of pavements on the IHS in good condition.
• Percentage of pavements on the IHS in poor condition.
• Percentage of pavements on the NHS (excluding the IHS) in good condition.
• Percentage of pavements on the NHS (excluding the IHS) in poor condition.

Condition of the pavements is to be determined based on the following metrics:⁽³⁾

• International Roughness Index (IRI).
• Cracking percent.
• Rutting.
• Faulting.

The pavement condition rating thresholds are provided in table 1.⁽³⁾ The overall condition of the pavement is determined based on the individual metric conditions as follows:

• For asphalt concrete (AC) and jointed portland cement concrete (JPCC) Highway Performance Monitoring System (HPMS) pavement segments, the pavement is classified as good condition if all three metrics are in good condition—IRI, percent cracking, and either rutting (AC) or faulting (JPCC), respectively. The pavement is classified as poor condition if two or more of the metrics are in poor condition. All other combinations of metric conditions classify a pavement as fair.⁽³⁾
  
  
• For continuously reinforced concrete pavements (CRCPs), if both metrics—IRI and percent cracking—are in good condition, the pavement is classified as good. The pavement is classified as poor if both metrics are in poor condition. All other combinations of metric conditions classify the pavement as fair.⁽³⁾

The Final Rule allows State DOTs to report Present Serviceability Rating (PSR) instead of metrics where the speed limit is under 40 mph.⁽³⁾ The pavement condition rating thresholds when using the PSR metric for all pavement types are provided in table 2.⁽³⁾

The Final Rule notes that each of the above pavement condition data metrics is to be collected on the full extent of the IHS in the rightmost travel lane in the inventory direction of mainline travel on an annual basis.⁽³⁾ For the non-interstate NHS pavements, data are to be collected on the full extent of the rightmost lane in one direction of travel on a biennial frequency.⁽³⁾ Percent cracking, rutting, and faulting are not required to be collected on the non-interstate NHS until the 2020/2021 data collection cycles.⁽³⁾

The efforts of the study that led to these guidelines were undertaken to validate the proposed pavement performance measures issued as part of the Notice of Proposed Rulemaking and ultimately to support the measures established in the Final Rule.⁽⁴⁾ Due to the completeness and volume of data contained in the Long-Term Pavement Performance (LTPP) Pavement Performance Database, the LTPP program was poised to assist in implementation of the MAP-21 legislation—both the validation of the performance measures as well as the development of these guidelines. The validation of the performance measures is documented in a companion report to these guidelines.⁽⁴⁾ Users of the guidelines presented in this report are encouraged to read the companion validation study report, as it provides the background and analysis that resulted in the recommendations presented herein.

Objective

The objective of these guidelines is to provide information and guidance to highway agencies on the following key pavement decisionmaking issues:

• Method to identify which condition metric is driving the performance measure.
• Temporal effects on performance measures.
• Effects of maintenance and rehabilitation (M&R) treatments on performance measures.

The goal of the guidelines is to illustrate to agencies what needs to happen to move the overall condition from poor to fair to good. In meeting this goal, the guidelines will enable highway agencies to address critical questions such as the following:

• What are the drivers of the performance measures?
• What are the effects of M&R treatments on condition metrics and overall condition?
• How can performance measures be improved from poor to fair, poor to good, and fair to good?

Figure 1 presents a flowchart summarizing the approach detailed in the guidelines. The flowchart begins with the development of performance measure drivers for both the metric condition and the overall condition. The performance measure drivers are then combined with the effects of M&R treatments on the metric and overall condition. These findings are then used to develop a list of M&R treatments that affect the condition. The final step in the process is the integration of the results with the pavement management system (PMS).

Guidelines Organization

The guidelines present recommended procedures for assessing the effectiveness of M&R treatments to improve overall condition and performance measures. The chapters included in these guidelines are summarized below along with a brief description of their contents:

1. Introduction—provides the background, objectives, and organization of the guidelines.
2. Development of Performance Measure Drivers—details how to develop the performance measure drivers.
3. Assessing the Effects of M&R Treatments—presents the effects of M&R treatments on metric and overall conditions.
4. Treatments Affecting Performance Measures—combines the effects of M&R treatments with the performance measure drivers to develop a list of M&R treatments that affect condition.
5. Summary, Challenges, and Recommendations—summarizes the findings from the previous chapters. In addition, challenges for integrating the findings of the guidelines with PMS results are presented and recommendations made.

The examples, conclusions, and recommendations developed in these guidelines are based on LTPP data. Highway agencies should review and analyze their own data to confirm that the LTPP-derived information is applicable to their agency and, if not, make the needed adjustments based on the examples provided in the guidelines.

Source: FHWA.
Figure 1. Flowchart. Guidelines general approach.