U.S. Department of Transportation
Federal Highway Administration
1200 New Jersey Avenue, SE
Washington, DC 20590

Skip to content
Facebook iconYouTube iconTwitter iconFlickr iconLinkedInInstagram

Federal Highway Administration Research and Technology
Coordinating, Developing, and Delivering Highway Transportation Innovations

This report is an archived publication and may contain dated technical, contact, and link information
Back to Publication List        
Publication Number:  FHWA-HRT-13-050    Date:  November 2013
Publication Number: FHWA-HRT-13-050
Date: November 2013


Pavement Remaining Service Interval Implementation Guidelines



Many decisions need to be made in order to successfully provide and manage a pavement network. The main decision is the prediction of future construction events, which is the fundamental basis of engineering design and management of pavement structures. Future construction events include the do nothing alternative, routine reactive maintenance, preventive maintenance and preservation activities, alternative rehabilitation treatments, and reconstruction.

The goal of pavement management is to optimize agency resources while providing a maximum level of service to users. Accomplishing this goal requires monitoring the condition of the pavement network and forecasting future pavement performance in order to effectively plan future pavement construction events. Predicting RSL of the segment units that make up the pavement network is of paramount importance to pavement management planning. Knowing or estimating the future condition of pavement sections is the rational basis of informed pavement infrastructure planning.

Remaining service is typically defined as the period over which a pavement section adequately performs its desired function or performs to a desired level of service. RSL is the time from the present (i.e., today) to when a pavement reaches an unacceptable condition and requires construction intervention. The central role of RSL in pavement management business decisions is predicting the change in pavement condition as a function of time, traffic loading, and environment. The basic difference in the RSL models used at the project, network, and contract administration levels is data requirements related to level of technical detail, extent, quality, precision, and accuracy.

While the prediction of time until a construction treatment should be applied is a critical component at all levels of pavement management decisions, many issues exist in the current RSL terminology, which confuse, confound, and complicate proper interpretation, interagency data exchange, and use.

One common RSL definition is the time until the next rehabilitation or reconstruction event; however, 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. Rehabilitation treatments are typically applied before a pavement has suffered extensive structural damage, while reconstruction treatments are generally warranted after a pavement has reached an advanced degree of deterioration. Attempting to interpret combined RSL estimates from mixed rehabilitation and reconstruction units provides little information to decisionmakers. Also, the timing of the next rehabilitation or reconstruction event will depend on what future lower-level treatments are applied.

Another common RSL definition is the time until a condition index threshold limit is reached. This definition not only has the same issues as rehabilitation and reconstruction RSL units, but it also introduces other service and safety condition indices that further complicate the meaning of RSL. Setting threshold limits for pavement conditions that are not based on human subjective ratings, such as cracking, can be complicated to justify. Moreover, interpretation of a single RSL number becomes even more complicated when it is based on multiple condition states. For example, if RSL for roughness is 2 years, RSL for cracking is 5 years, RSL for friction is 7 years, and RSL for rutting is 20 years, expressing that the current pavement RSL equals 2 years can lead to faulty construction decisions since the construction treatment to correct roughness may ignore the more serious cracking issue expected to occur soon after the roughness threshold is reached. Since there are many construction treatments that can be used to correct excessive pavement roughness that can be classified as pavement preservation, this approach adds maintenance-type activities to RSL units.

Another intriguing aspect of RSL based on threshold limits is negative RSL. When a Pavement Condition Index (PCI) limit is reached, the number of years it remains in service after this time could be considered a negative service life, which is counterintuitive. One approach is to set negative values to zero, thus not allowing a negative RSL value to be provided by the process. Another approach is to consider negative RSL as overdue needs, in which case the number of years overdue can be considered as useful information to decisionmakers if they know the basis of the condition in need of attention.

Another approach to RSL is based on agency management rules on the time between applications of corrective pavement construction treatments. For example, a State highway agency (SHA) with a relatively small number of interstate highway lane-miles may decide, based on past performance, to apply a resurfacing, rehabilitation, or reconstruction treatment every 8 years to each construction segment unit on the system to keep their highest level functional class pavements in the best condition. The RSL becomes the difference in time between the construction frequency established and how long it has been since the last treatment was applied. While this approach simplifies the decisionmaking and project selection process, it does not typically result in the most cost effective solution.

An unintentional consequence of using current RSL terminology is that it tends to promote “worst-first” approaches to correcting pavement deficiencies. By expressing pavement condition in terms of RSL, it is expected that pavements in the worst condition get treated first; however, construction treatments on pavements in the worst condition tend to cost the most. Applying a life-extending corrective rehabilitation treatment before the pavement condition gets too bad tends to cost less than reconstruction treatments. Optimum allocation of annual pavement resurfacing, rehabilitation, and reconstruction budgets will include pavements with differing remaining lives and should not be based solely on a worst-first approach.

Reformulating RSL Terminology

The objective of this document is to provide a definition and process for determining pavement RSL that will promote consistency in the use of the terminology. Currently, many RSL definitions are used to describe different events in the construction history of a pavement. Construction-related history best describes the use of RSL models at all levels of the pavement management decision process because the primary purpose of predicting pavement RSL within the context of pavement management is to plan for future field construction event(s) (i.e., maintenance, preservation, rehabilitation, reconstruction, or other treatments to correct some attribute of the pavement structure).

A major source of uncertainty in the current definition is the use of the term “life” to represent different points in the construction history. 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, after construction of the pavement structure, the as-constructed properties become more important in pavement life expectations than the assumed inputs into the original design process. A pavement structure can be thought of as a system whose components include subgrade treatments, subsurface drainage features, base layers, shoulders, bound structural load bearing layers, and surface layers. As a repairable system, the life of the system is not defined by correctable component failures.

The proposed solution is to remove the word “life” from the lexicon since it is the basis for confusion. Instead of using RSL, it is recommended to adopt the term RSI, which indicates the time remaining until a defined construction treatment is required.

Adoption of a definition related to construction treatments opens up the vocabulary to treatments related to other factors besides pavement condition. For example, if a construction cycle is defined in terms of the time until the next construction event requiring lane closures, then capacity improvements, shoulder widening, utility construction, and realignment construction activities can be included in the construction event. In turn, this broadens the application of the definition in the future. In some situations, capacity issues can have more of an effect on the service provided by a pavement structure than the condition of the pavement surface, or the pavement has reached a level where the next utility cuts and resulting repairs can be performed within a defined time period. This shifts the emphasis on the life remaining in a pavement structure to the time remaining until the next planned construction lane closure is required or future construction is needed.


This report provides a more refined construction activity needs analysis terminology and approach to reduce potential confusion over the use of the RSL nomenclature. To accomplish this task, this report is organized into the following sections:

These guidelines have been developed based on the results of the effort carried out under the Federal Highway Administration (FHWA) project, “Definition and Determination of Remaining Service and Structural Life.” These results have been documented in the FHWA publication, Reformulated Pavement Remaining Service Life Framework.(1) Users are encouraged to read this report prior to implementing the RSI concept, as it provides the foundations for the concept along with other valuable information such as basic pavement design and management concepts, RSL models, and the results of the literature review performed as part of the project.