Long-Term Pavement Performance Ancillary Information Management System (AIMS) Reference Guide

ANCILLARY INFORMATION

Ancillary information includes data, images, reference materials, resource documents, and other information that support and extend the data stored in the Pavement Performance Database (PPDB) related to understanding the performance of pavement test sections included in the LTPP program.⁽¹⁾ All of the electronic ancillary information is stored at the Federal Highway Administration (FHWA) Turner-Fairbank Highway Research Center (TFHRC) in McLean, VA, in what is called the Ancillary Information Management System (AIMS). AIMS comprises a set of internal tools used by LTPP staff to manage the vast amount of electronic data. While the majority of AIMS data are contained in PPDB in some form, some types of raw data that are summarized in the database are only available from AIMS.

Figure 1 illustrates the current terminology used by the LTPP program to describe the overall system to manage information intended for public dissemination for pavement performance research purposes. The total system is called the LTPP Information Management System (IMS), which includes products, PPDB, and AIMS as the major categories. Products are program results that can be used to improve pavement performance. PPDB is the formal database that contains the majority of research data on the performance of the LTPP test sections in an electronic relational database format. AIMS contains the larger electronic base of raw data files used to populate PPDB and other information not contained in PPDB.

Figure 1. Illustration. Major categories of the LTPP IMS.

LTPP provides access to its ancillary information in the interest of linkage between the collected raw data and the summaries of processed data contained in the publicly disseminated database. Accessibility to the raw base line measurement data increases the potential for reinterpretation using new future data concepts. A simple example of a data concept is the International Roughness Index (IRI). Providing access to the raw longitudinal profile (LPF) data allows other types of indices to be computed, such as an index based on dynamic truck loads. Note that IRI is based on passenger car suspension.

Ancillary information is provided without any indication of data quality. While some elements may have undergone quality reviews, some of the electronic files contained in AIMS are raw files that may not have been edited to correct errors discovered during database processing. AIMS also contains data that may not have been loaded into the database for quality concerns or other reasons (e.g., the data were collected after the out-of-study date). LTPP ancillary information users assume responsibility for performing their own checks on data quality and assessment of the appropriateness of the data or information for their intended purposes.

A brief summary of the ancillary data available from the LTPP program is presented in table 1. Not all of the data indicated in table 1 are available for all test sections, equipment evaluations, traffic measurements, etc.

Table 1. Summary of LTPP ancillary information.

The 1.4-inch (35-mm) photographic images of test section surfaces used as the primary basis for distress interpretation at the start of the program have not been completely converted into electronic format. This is currently the most significant issue in digitization to complete the electronic AIMS. While not all of the available film has been converted to an electronic format, the physical photographic media still contains greater resolution than the pixilated digital images. The following sections provide more information on the general nature of the available ancillary information following the categories listed in table 1. Appendix A provides additional details on general types of files and file naming conventions.

AUTOMATED WEATHER STATION

Automated weather stations (AWSs) were installed at selected Specific Pavement Study (SPS)-1, SPS-2, and SPS-8 experiment sites. AWS data available from AIMS include raw electronic data files downloaded from data loggers connected to the AWSs and data files produced by the pre-upload computer program used by the LTPP regional support contractors (RSCs) to review, edit, and create database upload files from the raw data for entry into PPDB.

DRAINAGE INSPECTION

Ancillary LTPP information includes the data from inspection of the subsurface drainage structures at SPS-1 and SPS-2 project sites. The inspection data includes measurements and information recorded on paper data collection forms and video images. The video images from a remote camera inserted into the drainage system outflow exits and passed as far into the subsurface drains as possible are available in digital format.

DYNAMIC LOAD RESPONSE

Dynamic load response (DLR) data were collected at the North Carolina SPS-2 site and the Ohio SPS-1, SPS-2, SPS-8, and SPS-9 sites. The available DLR ancillary information not contained in PPDB are the raw time-history data files in American Standard Code for Information Interchange (ACSII) format produced by the strain, pressure, and linear variable differential transformer measurements under moving truck wheel loads.

AIMS contains more DLR measurement files than those uploaded into PPDB due to processing issues. Data users interested in LTPP DLR data must contact the LTPP Customer Support Service Center (CSSC) in order to obtain the most current data and information on problems discovered with past releases of DLR data.

FALLING WEIGHT DEFLECTOMETER

Falling weight deflectometer (FWD) measurements were performed on test sections to measure the deflection response of the pavement structure. In addition to the raw data produced by the automated FWD measurement device, associated data include manual pavement temperature gradient measurements and FWD calibration data.

The raw electronic data files from the FWD device are stored in AIMS. While the test time, test location, equipment calibration settings, equipment configuration factors, air and pavement temperature, and peak deflection basin measurements are stored in PPDB, the time-history deflection and load sensor measurements are only available from AIMS.

When FWD measurements are performed on LTPP test sections, measurement of the subsurface temperature of the bound surface pavement layers at various depths are performed using external instruments. The paper data sheets used to record these data in the field have been electronically scanned and are stored in AIMS.

LTPP FWD data undergo a variety of quality control (QC) checks. Calibrations are performed using a combination of relative and reference procedures. Measurement data are also subjected to automated data checks prior to uploading into PPDB. AIMS includes the raw electronic files generated during these calibrations and pre-upload data checks.

FRICTION

Friction measurements are performed by participating highway agencies on a voluntary basis using their equipment. The measurements are recorded on paper data forms that are submitted to LTPP for entry into PPDB. The scanned images of the paper data collection forms used to report data are saved in electronic format in AIMS.

GROUND-PENETRATING RADAR

Ground-penetrating radar (GPR) measurements were performed in 2003 on all SPS-1 projects that were still in-service at the time. Measurements were also performed on selected SPS-2, SPS-5, and SPS-6 project sites.

The ancillary information from these GPR measurements includes the raw data files containing readings every 6 inches (152 mm), a graph of the data contained in the raw data file, a graph of the interpreted dielectric constant versus position, a graph of the interpreted layer thicknesses versus position in the right wheel path and center of the lane, and the upload files used to populate the table in PPDB that contains the interpreted results.

INVENTORY DATA

Inventory data include pavement age, general location, pavement type, layer thicknesses and types, material properties, composition, previous construction improvements, and other background information obtained from agency files for pavement structures in-service prior to LTPP monitoring. The data are reported to LTPP by participating highway agencies on paper data collection forms. Images of the paper data collection forms used to collect this data are saved in electronic scanned format in AIMS.

LPF

LTPP LPF measurement ancillary information includes raw data files from high-speed inertial profile measurements on pavement test sites and weigh-in-motion (WIM) scales and manual measurements on remote test sites using the dipstick device.

The majority of LTPP LPF measurement data were collected using high-speed inertial profilers. The raw data files and database files generated by the LTPP pre-upload data processing software are stored in AIMS. LTPP LPF data include measurements performed on pavement test sections and at WIM scale measurement sites.

A small subset of LPF measurement data was collected using a manually operated dipstick device. Ancillary information from dipstick measurements includes an image scan of the paper data collection forms and electronic data files generated during the pre-upload processing of these data.

The 1-inch (25-mm) interval longitudinal pavement profile data available from the more modern profilers are not contained in PPDB and are only available by request to LTPP CSSC. All LPF measurements at WIM scale sites are stored only in AIMS.

MAINTENANCE AND REHABILITATION

Maintenance data modules (MNTs) and rehabilitation data modules (RHBs) include data for maintenance and rehabilitation construction events performed after LTPP monitoring of the test sections had begun. These data are reported on paper data collection forms. Images of the paper data collection forms used to collect this data are saved in electronic scanned format in AIMS.

MATERIAL TESTS

This data type contains field tests and laboratory test results on material samples obtained from the LTPP test sections. The majority of these data are reported on paper data collection forms. Images of the paper data collection forms used to collect these data are saved in electronic scanned format in AIMS.

PAVEMENT DISTRESS

The major categories of LTPP pavement distress ancillary information are manual distress, automated photographic distress, manual TPF measurements, and data from automated quality review records.

The manual distress ancillary information includes scanned images of the paper field data distress maps, paper data collection sheets, and digitized images from photographs taken during a manual distress survey (MDS). The electronic database that documents the basic information on the location of each manual distress photographic image file is also contained in AIMS.

A significant exception to the definition of AIMS data being electronic files are the pavement images recorded on 1.4-inch (35-mm) black and white film. Two sets of film are available. One set of film was used to record the image of the pavement surface. These images were used as the basis for surface distress interpretations from raters. The other film set was used to measure the distortion in the pavement TPF using an optical image analysis process. All original raw 1.4-inch (35-mm) film media is stored in a climate-controlled facility at the Materials Reference Library. Approximately 2,000 images collected between 2002 and 2004 have been electronically digitized and stored in AIMS. Users desiring access to view raw film format must make arrangements through the LTPP CSSC.¹

Manual TPF measurements performed using the dipstick measurement device are recorded in the field on paper forms. The data from these paper forms are entered into a pre-upload processing software that checks the data, performs quality checks, and generates PPDB upload files. AIMS contains electronically scanned images of the field paper data collection forms and files generated by the data processing program.

Other pavement distress information stored in AIMS that are not available in PPDB includes images of the hand-drawn distress maps that indicate the location of the various distresses from the manual surveys, computer-generated maps from interpretation of 1.4-inch (35-mm) film, digitized images from photographs taken during MDSs, and digitized images from the 1.4-inch (35-mm) photography.

¹ The 1.4-inch (35-mm) film contains a continuous image requiring special equipment to view. One set of equipment for viewing this film exists at TFHRC.

RESILIENT MODULUS MATERIAL TESTS

Resilient modulus tests were performed on asphalt concrete cores and unbound aggregate/ subgrade material samples following the LTPP P07 and LTPP P46 test protocols.^(2,3) The LTPP P07 test protocol is a test procedure that includes resilient modulus, creep compliance, and tensile strength from asphalt concrete core samples tested in indirect tension. The LTPP P46 protocol is a resilient modulus test performed on unbound base and subbase materials in compression mode. The raw time history data files from the parts of these laboratory tests based on repeat cyclical load/response measurements are contained in AIMS.

Only a partial record of the raw LTPP P46 test protocol time-history data on unbound materials exists since the original laboratory contractors were not required to submit these data.

SEASONAL MONITORING PROGRAM

The data in the Seasonal Monitoring program (SMP) module contain processed raw and interpreted data from instrumentation and other measurements performed on these sites. The SMP ancillary information includes the raw electronic instrumentation data files, edit files from the software program that were used to perform primary quality checks on the raw data and produce the PPDB upload files, and scanned electronic paper data collection forms.

SPS

This module includes general and construction information collected from the test sections included in the SPS experiments. These data are entered on paper data collection forms. Images of the paper data collection forms used to collect the general and construction data contained in this module are saved in electronic scanned format in AIMS.

TEST SECTION COORDINATES

Test section coordinates are measurements or estimates of test section locations using Global Positioning System technology or other modern mapping techniques. These measurements are recorded on paper data collection forms. Images of the paper data collection forms used to collect this data are saved in electronic scanned format in AIMS.

TEST SECTION VIDEOS

The following types of test section videos have been electronically digitized and are available:

• Walking inspections of test sections: During the initial inspection of test sections at the start of the program, videos showing the test section surface and surrounding terrain were made on some sections. Walking inspection videos were also created during MDSs on some sections. The videos were taken by staff walking the length of each test section, and they contain an oral narrative of significant features.

• Through-the-windshield video from the high-speed profiler: Video cameras were mounted in some of the LTPP profilers, and videos of the test sections were recorded through the windshield during measurements. These videos were used to check on the general condition of each test section and to detect maintenance activities. These video recordings were performed by only some regional LTPP data collection contractors and are available for a subset of test sections.

TRAFFIC

LTPP traffic data ancillary information includes traffic measurement input files used by the LTPP Traffic Analysis Software (LTAS) files created by legacy LTPP traffic QC (LTQC) software and versions based on Statistical Analysis Software^® (SAS^®), files from the International Road Dynamics Inc. (IRD) iANALYZE^® software, and scanned paper data forms. The SAS^® binary file formats are no longer supported.

LTAS reads data files formatted in a FHWA Traffic Monitoring Guide (TMG) format for classification or weight data, performs traffic data QC checks, provides data graphs for semi-automated data checks by regional staff, creates a variety of quality assurance reports, and creates the annual traffic data statistics stored in PPDB.⁽⁴⁾ The internal database files created by LTAS are now part of the LTPP standard data release (SDR). The AIMS component of LTAS-related data contains output files in the TMG format.

The first contractor was selected to install WIM scales at select LTPP test section locations as part of the LTPP SPS Traffic Data Collection Pooled Fund Study. AIMS includes vendor proprietary binary raw data output and ASCII versions of the same data produced by the iANALYZE^® software.

The traffic ancillary information also includes electronic images of the paper data forms used to report basic traffic information, traffic scale calibration, historical traffic, and traffic estimates produced by the agency when no onsite measurements were performed.