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LTPP Jargon File

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This jargon file will contain both LTPP jargon, and commonly used terms in the pavement engineering field.


see asphaltic concrete


An acronym for "Auxiliary Information Management System". The AIMS contains data that can not yet be properly handled by the IMS, such as digitized distress maps and FWD time history files.


a sticky, viscous liquid fraction found in most crude oils

asphaltic concrete

A material commonly used in pavements. It is primarily composed of crushed stone and asphalt


In the field of pavement engineering, the term backcalculation is used to refer to the process of determining the elastic moduli of layers in a layered system based on surface deformations due to applications of known loads. Datasets used in backcalculation are generally generated by falling weight deflectometers.


A material used to cement loose materials together


A material that is completely soluble in carbon disulfide. Asphalts and tars are the most common bituminous materials.

dynamic modulus

Generally, Dynamic Modulus is defined as a modulus calculated under non static loading conditions. In the context of pavement materials, Dynamic modulus is more narrowly defined as the value of peak-to-peak stress divided by peak-to-peak strain of a material under sinusoidal loading at a given frequency of loading.

falling weight deflectometer

A device that measures the deformation response of a pavement due to a load generated by the arrest of a falling mass.


See falling weight deflectometer

hydraulic cement

A cement that depends on a chemical reaction with water to produce a bond. The most common type of hydraulic cement is Portland cement.


An acronym for "Information Management System". The IMS is a database specification designed to contain virtually all (see AIMS) of the data collected by LTPP. The IMS has been evolving and growing since LTPP first began in 1988, and is scheduled to achieve sentience by 2021. The IMS is currently implemented in two forms, the NIMS, and the RIMS.

Long Term Pavement Performance

Commonly known by its acronym, LTPP, the Long Term Pavement Performance program is an extensive research project that is investigating the factors that affect the performance of pavements throughout the United States and Canada. For more information, please see the LTPP homepage.


See long term pavement performance.

mechanistic-empirical design

A design method which includes both fundamental engineering properties and empirical "calibration factors" as inputs. The calibration factors are meant to account for localized or otherwise difficult to model minor effects.


An acronym for "National Information Management System". The NIMS is a central database to which data from the four regional databases, or "RIMS" is uploaded. All public releases of LTPP data are from the NIMS. See also IMS.


An acronym for "Regional Coordination Office". This term has been superseded by "RCOC", which in turn has been superseded by "RSC"


An acronym for "Regional Coordination Office Contractor". This term has been superseded by "RSC"

resilient modulus

Stiffness of a material under cyclic loading calculated using only recoverable strain. In the field of pavement materials, the loading waveform used is generally "haversine" to better simulate actual wheel loading. LTPP has developed laboratory testing protocols for determining the resilient modulus of unbound materials and asphalt materials.


An acronym for "Regional Support Contractor". There are four RSCs: North Atlantic (NARSC), North Central (NCRSC), Southern (SRSC) and Western (WRSC). The RSCs are responsible for data collection and entry in their respective regions.


A subjective measure of a pavement's smoothness

seasonal monitoring program

A sub-program within LTPP, the seasonal monitoring program, or SMP studies seasonal effects on pavements through multiple rounds of FWD testing over the course of a year. SMP sites also include on-site automated weather stations (AWS), and permanently installed thermistors and time-domain reflectometry (TDR) equipment at multiple depths in the pavement structure.


See seasonal monitoring program


An acronym for "Technical Assistance Contractor". This term has been superseded by "TSSC"


An acronym for "Technical Support Services Contractor". The TSSC is responsible for performing Quality Assurance on LTPP data, operating the NIMS and development of the IMS.