Long-Term Pavement 

Performance Program

Accomplishments and Benefits 1989–2009 

The Long-Term Pavement Performance (LTPP) program began 

in 1987 as part of the Strategic Highway Research Program 

(SHRP). Its primary purpose was to establish a national longterm pavement database to support pavement research 

and improved pavement performance. When SHRP ended as 

planned in 1992, the LTPP program continued under the Federal 

Highway Administration with the participation of highway 

agencies in all 50 States, the District of Columbia, Puerto Rico, 

and 10 Canadian Provinces.

Since 1989, the LTPP program has monitored nearly 2,500 

pavement test sections throughout the United States and 

Canada. Approximately 950 test sections are still being monitored today. By collecting and analyzing data from these pavement test sections over time, researchers are gaining insight on 

how and why pavements perform as they do—learning how to 

build better, longer lasting, more cost-effective pavements.

Developing Pavement Performance Data

Over the past 20 plus years of data collection, LTPP has produced 

a wide array of accomplishments and benefits and has created a 

variety of innovative products for highway agencies and researchers 

to utilize. Through partnership with key program stakeholders, the 

LTPP program has worked to fulfill each of its original objectives, 

SUMMARY 

with the ultimate goal of extending pavement life through better 

understanding of the factors that affect performance. 

The program’s single most significant product to date, as well as 

the largest source of information for current and future research, 

is the LTPP database. The database contains more research-quality 

data than have been collected anywhere before on the rate, type, 

and extent of pavement deterioration due to age, traffic loads, 

and weather, together with information on the design features 

and construction methods used to construct or rehabilitate the 

pavements.

LTPP data has contributed to more cost-effective highway 

pavements by providing 

•	 More realistic pavement design models.

•	 Improved understanding of how and why pavements perform

as they do. 

•	 High-quality data on which to base pavement management

and rehabilitation decisions.

•	 Guidance to support selection of the most cost-effective

pavement design features for a given set of design constraints. 

•	 A knowledge base on which to develop educational curricula

for future generations of pavement practitioners. 
What Have We Learned?

Researchers have examined many questions about pavement performance in the more than 600 publications produced using LTPP 

data. Many of their findings have led directly to cost-saving changes 

in highway agency practices. Here are a few examples:

•	 TheColoradoDepartment ofTransportation (DOT) has been examining performance at its LTPP test sections and making improvements based on these evaluations. Two findings, derived directly 

from LTPP data, have led to improved practices for constructing 

portland cement concrete pavement: 1) widening a slab from 12 ft 

to 14 ft (3.7 m to 4.3 m) provides the structural equivalent of 

increasing slab thickness by 1 in. (2.54 cm); and 2) a single 1/8-in. 

(0.32-cm) cut is as effective as Colorado DOT’s previous standard 

3/8-in. (0.95-cm) double cut for PCC joints and provides a savings 

of $0.57 per linear foot ($1.87/m) of joint. 

•	 In Texas, researchers analyzed the relative cost-effectiveness of

various maintenance treatments using ride quality and distress 

score data from LTPP test sites. Analysis showed that chip seals 

were a more cost-effective alternative compared to slurry seal 

and a 1-in. (25-cm) overlay. 

•	 The use of LTPP centers for calibrating falling-weight deflectometer (FWD) equipment by highway agencies and consultants 

revealed that many FWDs were significantly out of calibration. 

Proper calibration of this equipment has resulted in significant 

construction savings in situations where design is driven by 

FWD measurements. The Indiana DOT, for example, discovered 

that an FWD out of calibration by only 1 mil resulted in additional construction and maintenance costs of $17,900/mi. 

($11,187/km).

•	 LTPP performance data in a national study revealed that recycled

asphalt pavement (RAP) and virgin hot-mix asphalt used in 

overlays of flexible pavements show approximately the same

performance across a wide range of climates, traffic, and existing 

pavement conditions over a service life ranging up to 17 years. 

This major finding should give agencies confidence in specifying 

RAP mixtures for overlays when economic and other conditions 

warrant.

The single most significant product to date from the LTPP program, 

as well as the largest source of information for current and future pavement research, 

is the LTPP database.

Innovations and New Products

The LTPP program has generated savings across a wide range of 

pavement management activities, improving field data collection 

equipment and operations, establishing data variability and reliability, 

and providing quality data sets to be used for baseline comparisons 

against agency data. Many advances in data collection practices developed through LTPP research have been adopted by State/Provincial 

and local agencies—90 percent of State highway agencies report 

having used LTPP data collection equipment or test methods.

Numerous LTPP data collection procedures have been adopted 

by the American Association of State Highway and Transportation 

Officials (AASHTO) and industry, with the most widely implemented 

being the Distress Identification Manual. 

For bound and unbound resilient modulus testing, the LTPP 

program established laboratory startup procedures to ensure that 

accurate, comparable results can be obtained. The procedures were 

developed specific to the resilient modulus protocols, but can 

broadly be applied to setting up closed-loop servo-hydraulic testing 

equipment. This procedure has been adopted by equipment manufacturers as a quality control check during equipment production.

Direct measurements at Seasonal Monitoring Program projects 

and automated weather station locations have provided designers 

and researchers with an abundance of high-quality environmental 

data. The further step of developing virtual weather stations has 

already paid significant dividends (an estimated $50 million per year 

for LTPPBind alone), and all environmental data will support significant future savings.

Improving material characterizations for bound and unbound layers 

is critical for advancing mechanistic-based designs. The LTPP program 

has provided many advances across this spectrum—from establishing 

testing protocols and increasing uniformity between testing labs to 

providing quality data for analysis activities. The Materials Reference 

Library will provide future analysts with the means to compare new test 

methods with actual performance using materials from LTPP projects.

For traffic and loading information, the LTPP Weigh-in-Motion 

(WIM) Cost Online and the LTPP WIM Smoothness Index software 

provide agencies with tools to evaluate the cost and pavement 

smoothness requirements for WIM installations. In addition, LTPP 

guidelines on calibrating and validating equipment allow loading 

and classification information to be used with confidence. 
LTPP’s Critical Role in Pavement Design

The LTPP database has played a critical role in the development and 

evaluation of every major pavement design methodology developed 

over the past 20 years. This includes the 1993 and 1998 AASHTO 

design procedures, SuperPave®, and—most recently—AASHTO’s 

Mechanistic-Empirical Pavement Design Guide (MEPDG). This new 

pavement design procedure gives engineers improved tools for 

specifying the optimum mix, layer configuration, and thickness for 

new and rehabilitated pavements. 

The MEPDG would not have been possible without LTPP data for 

many inputs. Calibrated nationally with LTPP sections, the MEPDG has 

shown significant reductions in the initial cost for heavily trafficked 

pavement designs, and its use is expected to generate annual savings 

of $1 billion. 

The LTPP database is also serving as a critical tool in implementing 

the new design guide. For the MEPDG to be an effective resource for 

individual agencies, the national models need to be evaluated against 

local and regional performance to determine whether local calibration 

is required. Local validation and calibration will rely heavily on the LTPP 

database as many agencies do not otherwise have the data necessary 

to complete this endeavor. 

Beyond overall design procedures, the LTPP data has supported 

and will continue to support model development and validation for 

a wide array of performance predictors and indicators.

A Foundation for Advancement

The LTPP database will continue to be the single largest benefit from 

the LTPP program. Providing reliable pavement performance data to 

thousands of requestors throughout the academic community and 

the public and private sectors, the database has been the foundation 

for fundamental and applied research and the nucleus for advancements in pavement design and management processes. With the 

LTPP program continuing to enhance the quantity, quality, and 

accessibility of LTPP data, the database will be the catalyst for pavement advancements over the foreseeable future.

Future benefits will be achieved primarily through the exposure 

of engineers and researchers to the LTPP program and to the LTPP 

database. This has already begun, as many universities are incorporating the LTPP database in their undergraduate curricula. Familiarity 

with the program will facilitate the implementation of LTPP products—and increased exposure to LTPP products will result in applications beyond those currently envisioned.

The Road Ahead

Looking to the future, rehabilitating and maintaining existing pavements will become a much larger part of agencies’ pavement programs and budgets. The LTPP program has many rehabilitated test 

sections that were monitored for several years before rehabilitation 

and that likely have several more years of service life after rehabilitation. 

Capturing the full performance life of these projects through continued 

monitoring in the coming years will lead to a deeper understanding 

of the treatment options and yield future savings.

Furthermore, because projects in Specific Pavement Studies 1 

and 2, which examine structural factors in flexible and rigid pavements, are most relevant to learning how specific design features 

influence pavement performance, and many of these projects are

not close to the end of their design lives, monitoring will continue. 

Data exist to support early conclusions, but additional information is necessary to learn the true impacts of these features over a 

pavement’s entire design life.

The LTPP program is an ongoing activity that will yield additional 

benefits as data are added to the database and as new data analysis 

efforts are completed.

Learn More

For more information on the LTPP program and how its products are 

being used to improve our highway system and ensure that our 

highway dollars are well spent, refer to the expanded version of this 

report, Long-Term Pavement Performance Program: Accomplishments 

and Benefits 1989–2009, and other resources at the LTPP Web site 

(www.fhwa.dot.gov/pavement/ltpp). In addition, an extensive database of LTPP reports, products, and research results is posted at 

http://ltpp.org/user_corner.shtml. Questions about LTPP data, products, and services can be directed to the LTPP Customer Support 

Service Center at ltppinfo@dot.gov.

Whether in the field or lab, LTPP measurement innovations 

and related products are benefiting the pavement community.
LTPP Highlights

The following is a sampling of products developed from the LTPP program. For more information, 

visit www.fhwa.dot.gov/pavement/ltpp/product.cfm.

DataPave Online

A specialized software application developed to help researchers and practitioners make sense 

of the large amount of data collected over the past 20 years and stored in the LTPP database. 

More than 3,000 researchers from 77 countries have already accessed the LTPP database and are 

using the data in local studies and analyses.

www.ltpp-products.com/DataPave

Rigid Pavement Design Software

A spreadsheet that automates the design and analysis procedures for improved guidelines for 

portland cement concrete pavements. The application makes it easier for highway managers and 

engineers to implement the guidelines developed under National Cooperative Highway Research 

Program research and validated with LTPP data.

www.fhwa.dot.gov/pavement/ltpp/rigid.cfm

Regional Falling-Weight Deflectometer Calibration Centers 

Established for the LTPP program and available for use by highway agencies and private firms 

for calibration testing. The costs of an incorrectly calibrated FWD quickly add up: the Indiana 

Department of Transportation found that an FWD that was only 1 mil out of calibration resulted 

in additional construction and maintenance costs of $17,900/mi.

www.fhwa.dot.gov/pavement/ltpp/fwdcont.cfm

Distress Identification Manual 

Provides a standardized means of identifying and recording cracks, rutting, spalls, potholes, and 

other evidence of pavement distress. The manual is now used by about half of the country’s 

State highway agencies, the FHWA, and many local agencies. 

www.tfhrc.gov/pavement/ltpp/reports/03031

LTPPBind Software Package

Allows highway agencies to select the proper grade of asphalt binder for a specific location. 

Temperature models developed under the LTPP program make it possible to consider the extreme 

high and low temperatures expected at a pavement site in the binder selection process. Highway 

agencies are saving more than $50 million each year using the LTPPBind software package.

www.fhwa.dot.gov/pavement/ltpp/ltppbind.cfm

Materials Reference Library

Offers researchers samples of the materials used to construct LTPP test sections. The library consists 

of more than 1,000 tons of materials, including pavement cores, asphalt cement, portland cement, 

and aggregate. The library ensures that materials used in LTPP sections will be available for future 

research projects.

www.ncenet.com/ltpp/mrl

Publication No. 

FHWA-HRT-10-072

HRDI-13/08-10(1M)E

Research, Development, and Technology

Turner-Fairbank Highway Research Center

6300 Georgetown Pike

McLean, VA 22101-2296 Recycled

Recyclable

Photo credits: Cover image, 

©istockphoto.com/SandSun. 

Images this page, Federal 

Highway Administration.