TECHBRIEF Pavement Remaining 

Service Interval 

FHWA Publication No.: FHWA-HRT-13-039

FHWA Contact: Nadarajah Sivaneswaran, HRDI-20, (202) 493-3147, 

n.sivaneswaran@dot.gov.

This document is a technical summary of the Federal Highway 

Administration reports, Reformulated Pavement Remaining Service 

Life Framework (FHWA-HRT-13-038) and Pavement Remaining Service 

Interval Implementation Guidelines (FHWA-HRT-13-050).

At the heart of pavement management decisions is the prediction 

of future construction events; however, many issues exist with the 

current remaining service life (RSL) terminology. The major source of 

uncertainty is the use of the term “life” to represent different points in 

the construction timeline. The path to consistency involves adopting 

terminology of time remaining until a defined construction treatment 

is required (i.e., RSL is replaced by remaining service interval (RSI)). 

The term RSI has the ability to unify the outcome of different approaches for determining needs by focusing on when and what treatments are needed as well as the service interruption created. This 

TechBrief introduces the RSI concept and its implementation process.

Background

Many decisions are necessary in order to successfully provide and 

manage a pavement network. At the heart of those decisions is the 

prediction of future construction events, which requires monitoring 

the condition of the pavement network and forecasting future performance. Predicting RSL of the network segments is critical; knowing or 

estimating future pavement condition is the rational basis for informed 

decisions. Many issues exist in the current RSL terminology that 

confuse and complicate its usage. 

One common definition of RSL is the time until the next rehabilitation 

or reconstruction event. These are two different events in terms of 

the condition of the pavement at the time of construction as well as 

the associated construction costs. Also, the timing of the next rehabilitation or reconstruction depends on future lower-level treatments 

applied.

Another common definition of RSL is the time until a condition 

threshold limit is reached. This approach shares the same issues as 

rehabilitation and reconstruction RSL units, but it also introduces other 

service and safety condition indices, which further complicate the RSL 

meaning. Interpretation of a single RSL number gets more complicated 

when it is based on multiple condition states. 

A third approach to RSL is based on agency management rules on 

the time between applications of corrective pavement construction 

treatments. In this approach, an agency creates policy rules on the 

Research, Development, and 

Technology

Turner-Fairbank Highway 

Research Center

6300 Georgetown Pike

McLean, VA 22101-2296

 www.fhwa.dot.gov/research
2

maximum time between applications of corrective 

treatments (e.g., place an overlay every 9 years). RSL 

becomes the time until the next treatment is scheduled. However, this approach does not provide for 

optimal distribution under a limited funds constraint 

scenario.

An unintentional consequence of using current 

RSL terminology is that it may promote the more 

costly “worst-first” approaches to correcting pavement deficiencies where the pavement is allowed to 

deteriorate to poor condition or its “threshold limit” 

before taking steps to rehabilitate it. By expressing 

pavement condition in terms of RSL, laymen and 

politicians expect that pavements in the worst condition are treated first, which tends to cost the most.

From a communication standpoint, while the engineer who computed a RSL value has full knowledge 

of what that life end point means, the current RSL 

terminology leads to possible misinterpretation by 

the recipient of the information. When RSL information is communicated, the details of the end point may 

not be obvious, and the recipient may interpret what 

that end point means. Compounding the issue, there 

are multiple definitions and interpretations for RSL 

that further aggravate the potential for misinterpretation. Even within pavement engineers and managers, 

RSL may have one meaning to those in preservation 

and another to those in design or budgeting.

Reformulating the RSL Concept

The major source of uncertainty in the current RSL 

definition is the use of the term “life” to represent 

different points in the construction history. The term 

“life” is interpreted differently by different stakeholders. In the pavement design context, “life” is used to 

represent the time until the as-designed pavement 

structure reaches an unacceptable condition. In the 

pavement management context, the as-constructed 

properties become more important in pavement life 

expectations. Moreover, as a repairable system, system life is not defined by the failure of a correctable 

component.

The proposed solution to the problem is to remove 

the word “life” from the lexicon since it is the basis 

for confusion. The recommended solution involves 

adopting a terminology of time remaining interval 

until a defined construction treatment is required (i.e.,

RSI replaces RSL). RSI has the ability to unify the outcome of different approaches to determine needs by 

focusing on when and what treatments are needed 

as well as the service interruption created. Adoption 

of a definition related to construction treatments 

also opens up the vocabulary to treatments related 

to other factors besides pavement condition.(1,2) 

RSI Concept Overview

The basic process to determine future pavement 

construction needs is illustrated in figure 1. Most 

pavement construction activity planning is based on 

an annual fiscal time cycle used by an agency. The 

process starts with input data that are fed into the 

performance prediction curves to produce predictions 

of future change in the construction trigger models. 

The outputs from the predictions are used to select 

the most appropriate construction strategy, which 

is used to develop construction plans and specifications. Monitoring measurements are performed to 

provide updated inputs for the next planning cycle 

and also to refine the prediction models.

Within the context of the process illustrated in 

figure 1, the fundamental elements required to 

replace the existing RSL terminology include the 

following:

•	 A controlled vocabulary to define pavement 

construction events. 

•	 A common basis for when the future construction event is needed. 

•	 Determination of how future needs are 

established (i.e., different levels of business 

decisions).

•	 Location and extent of the needed treatment.

Figure 1. Future pavement construction needs 

process.

Inputs

Prediction

Models

Strategy

Selection

Construction

Monitoring
3

The objective of the vocabulary is to uniquely define 

the type of future construction event need. The vocabulary requires identification of three attributes—time 

when a treatment is needed, type of construction 

treatment, and reason for the construction treatment. The following examples highlight construction 

event definitions based on the expanded paradigm 

of common pavement improvements included in 

many pavement management systems:

•	 Crack sealing: Application of sealants in surface 

cracks.

•	 Reconstruction: Removal and replacement of all 

bound layers of an existing pavement.

An indication of the reasons why a future construction

event is predicted is also needed to complete the 

definition since pavement improvements are based 

on different needs. The following examples explain 

the basis of predicted time to a threshold event: 

•	 Roughness exceeds limiting International 

Reference Index value.

•	 Cracking exceeds limit requiring reconstruction.

Typically, an agency will develop a decision matrix 

to use as part of its pavement management, which 

relates reason(s) for construction with types of construction events.

RSI Implementation Framework

The framework for implementing the new RSI terminology is illustrated in figure 2. The key components of the framework that should be addressed by 

highway agencies include generic and RSI implementation issues. The generic issues address the establishment of the agency’s RSI protocol, the identification 

of an RSI coordinator, and the dissemination of the 

RSI concept within the agency. These issues need 

to be addressed once with periodic monitoring and 

revisions to ensure that they are still appropriate.

The RSI implementation issues focus on a step-bystep approach necessary to successfully establish the 

concept within the agency. The six implementation 

steps are as follows:

1. Setting construction triggers: Construction triggers are measurable aspects or other aspects of a 

pavement’s condition that can be used to indicate

the need for a corrective treatment. Examples 

of construction triggers that may be considered 

by an agency include level of service, pavement 

distress, structural considerations, safety aspects, 

and agency time-based rules. 

2. Setting threshold limits: Threshold limits are 

used to indicate when a construction trigger

reaches a condition and when a construction treatment is needed. There are two general types of 

threshold limits—one related to road users (e.g.,

ride quality) and one based on agency economics

(e.g., cracking and faulting). Methods that can be 

used to establish threshold limits include subjective, engineering, empirical, economic analysis, 

and a combination of these methods.

3. Selecting or developing performance prediction 

curves: These curves are used to predict the time 

when the pavement condition will reach a construction trigger threshold. The current practice 

is to base the curves on the analysis of pavement 

performance observations, which requires longterm pavement condition data. When empirical 

data are not available, the creation of curves 

based on best available information can be used 

as a surrogate starting point to judge the relative 

performance of pavements. Performance prediction curve options include models based on 

design equations, empirical models, and agency 

time-based rules.

4. Identifying collection of inputs: The collection of 

data on the condition state of pavements under 

an agency’s jurisdiction should be based on the 

same construction triggers that form the basis 

for project-level decisions on construction needs. 

Potential inputs to the RSI process include pavement roughness, distress, structural response, 

traffic loads, and climate. In addition to these 

and other data inputs, it is important to give 

Figure 2. Agency RSI implementation.

Generic Agency Issues

1. RSI Protocol

2. RSI Coordinator

3. RSI Dissemination

RSI Implementation Issues

1. Construction Triggers

2. Threshold Limits

3. Performance Curves

4. Collection of Inputs

5. Strategy Selection

6. Assessments and Updates
4

Researchers—This study was performed by AMEC Environment & Infrastructure, Inc.

Distribution—This TechBrief is being distributed according to a standard distribution. Direct 

distribution is being made to the Divisions and Resource Center.

Availability—This TechBrief may be obtained from the FHWA Product Distribution Center by e-mail 

to report.center@fhwa.dot.gov, fax to (814) 239-2156, phone to (814) 239-1160, or online at http://www.

fhwa.dot.gov/research. The full report is available online at: http://www.fhwa.dot.gov/research.

Key Words—Remaining service life, Remaining life, Remaining service interval, Life-cycle cost 

analysis, Pavement management, Pavement rehabilitation decisions.

Notice—This document is disseminated under the sponsorship of the U.S. Department of 

Transportation in the interest of information exchange. The U.S. Government assumes no liability 

for the use of the information contained in this document. The U.S. Government does not endorse 

products or manufacturers. Trademarks or manufacturers’ names appear in this report only because 

they are considered essential to the objective of the document.

Quality Assurance Statement—The Federal Highway Administration (FHWA) provides highquality information to serve the Government, industry, and public in a manner that promotes public 

understanding. Standards and policies are used to ensure and maximize the quality, objectivity, utility, 

and integrity of its information. FHWA periodically reviews quality issues and adjusts its programs and 

processes to ensure continuous quality improvement.

may 2013 FHWA-HRT-13-039

HRDi-20/05-13(700)E

consideration to the missing data, measurement 

variability, sampling intervals, and frequency 

issues.

5. Establishing a strategy selection process: 

Selecting the most appropriate construction 

strategy has many facets and considerations that 

start with pavement condition subject to other 

constraints such as budget. At the network level, 

the objective is to characterize the current condition state of pavements in the network that 

require consideration of appropriate corrective 

treatments. The recommended practice is to use 

life-cycle cost concepts to optimize the selection of construction projects in the next cycle 

and forecast future construction needs. At the 

project level, the objective is to provide detailed 

decisions on what corrective construction treatments are needed for each project identified 

from network-level needs analysis. Life-cycle cost 

analysis can be supplemented with cost engineering considerations specific to the project.

6. Performing periodic assessments and updates: 

Formal assessments should be performed periodically to identify improvement opportunities. 

Based on the assessment results, updates to the 

models and processes used in the pavement 

management process are needed to adapt to 

technology change. 

Summary

The RSI concept does not provide an alternative 

to assessing the health of the network or making 

decisions about where to spend available funds. The 

concept provides a clear terminology and a logical 

process to move away from erroneous statements 

(i.e., “this pavement has only 5 remaining years of 

life”) and toward a consistent construction eventbased terminology and understanding. This promotes a common and consistent understanding of an 

agency’s pavement network assessment and funding 

needs among multiple and diverse stakeholders. An 

added benefit of adopting the RSI terminology is that 

it provides a readily available way to communicate 

impacts of alternate budget scenarios. 

References

1. Elkins, G.E., Thompson, T.M., Groeger, J.L., 

Visintine, B., and Rada, G.R. (2013). Reformulated 

Pavement Remaining Service Life Framework, 

Report No. FHWA-HRT-13-038, Federal Highway 

Administration, Washington, DC.

2. Elkins, G.E., Rada, G.R., Groeger, J.L., andVisintine, 

B. (2013). Pavement Remaining Service Interval 

Implementation Guidelines, Report No. FHWAHRT-13-050, Federal Highway Administration, 

Washington, DC.