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Publication Number: FHWA-RD-03-088
Date: November 2003

Introduction to The LTPP Information Management System (IMS)

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The Inventory (INV) module contains information on pavement structures that were in service up to 15 years prior to selection for monitoring as an LTPP test section. This includes all of the test sections classified in a GPS experiment or SPS maintenance and rehabilitation experiment for a CONSTRUCTION_NO of 1 as defined in the EXPERIMENT_SECTION table. For SPS projects, the information stored in the INV module represents the pavement structure prior to application of the experimental treatments. INV data include location of the section, pavement type, layer thicknesses and types, material properties, composition, previous construction improvements, and other background information.

The INV information is typically based on highway agency records for the construction project. The information may not represent specific conditions found at the portion of the project selected for monitoring. The information does not necessarily represent design values. The exception to this general rule is that the coordinate data are based on measurements taken by the LTPP program using global positioning system receivers.

LTPP Database Tip!

For SPS-3 and -4 projects that include a co-located GPS test section at the project site, information for the SPS project in the INV tables is coded to the GPS test section. The SPS_GPS_LINK table contains a mapping of SPS projects to data stored under the linked GPS test section.

7.1 INV TABLES

INV_ID: This table contains section location coordinates by route number and milepost, longitude and latitude, direction of travel, identification if the location is part of the FHWA Highway Performance Monitoring System, and county/parish name. Location information is provided in this table for sections classified in a GPS experiment or an SPS maintenance and rehabilitation experiment where CONSTRUCTION_NO = 1 in the EXPERIMENT_SECTION table. Location information for SPS projects that is based on construction of a new pavement structure is stored in the SPS_ID table.

INV_AGE: This table contains construction completion and traffic open dates for the original pavement structure based on highway agency records.

INV_LAYER: This table contains layer information from highway agency records. This information represents the pavement structure prior to LTPP monitoring. This table acts as a layer reference table for the other INV tables. INV tables that contain the LAYER_NO field reference the layer structure described in the INV_LAYER table. The layer structure in this table may differ from the actual layer structure found at the test site. The pavement structure data in this table are not recommended for use in analysis of performance monitoring measurements. The TST_L05* tables are the best representation of the actual pavement structure for each test section since they are based on field drilling and sampling measurements at the site.

INV_GENERAL: This table contains general information, including pavement type, lane width, number of lanes, subsurface drainage features, and an estimate of the depth to a rigid layer beneath the test section from agency records.

INV_GRADATION: This table contains data on the gradation of coarse, fine, and combined aggregates for PCC, AC, base, and subgrade. LAYER_NO in this table is used to link to the INV_LAYER table to indicate the type of layer. These data are based on agency project records.

INV_MAJOR_IMP: This table contains information on the type, quantity, and cost of major improvements to the test section prior to acceptance for LTPP monitoring.

INV_MODIFIER: This table contains information on asphalt modifiers used in plant-mixed asphalt (PMA)-bound layers.

INV_PCC_JOINT: This table contains information on formed joints in PCC layers, including joint type, joint spacing, load-transfer system, joint construction methods, joint seal ant, and tie bars.

INV_PCC_MIXTURE: This table contains PCC mix properties, including cement type, air entrainment, slump, and mix proportions.

INV_ADMIX: This table contains information on admixture type and amount for PCC layers.

INV_AGGR_COMP: This table contains information on aggregate composition for coarse, fine, and combined aggregates used in AC and PCC mixtures.

INV_AGGR_DUR: This table contains information on aggregate durability in AC and PCC mixtures.

INV_PCC_STEEL: This table contains information on steel reinforcement in PCC layers, including reinforcing steel type, diameter, design amount of longitudinal reinforcing, depth, and installation method.

INV_PCC_STRENGTH: This table contains available strength data from highway agency records for PCC layers, including flexural strength, compressive strength, and splitting tensile strength.

INV_PMA: This table contains information on PMA-bound layer aggregate properties, including bulk specific gravity , effective specific gravity, mineral fillers, and polish value.

INV_PMA _ASPHALT: This table contains information on the asphalt cement used in PMA-bound layers, including asphalt grade, source, specific gravity, viscosity, penetration, ductility, and softening point.

INV_PMA _COMPACTION: This table contains information on field compaction of PMA-bound layers, including type of compaction equipment, coverage, air temperature, compacted thickness, and curing period.

INV_PMA _CONSTRUCTION: This table contains information on field construction of PMA-bound layers, including mixing temperature and lay-down temperatures.

INV_PMA _ORIG_MIX: This table contains available agency information from laboratory- and field-compacted specimens on the mix properties of PMA-bound layers. Data included in this table are maximum specific gravity, bulk specific gravity , asphalt content , air voids, voids in the mineral aggregate, mix design stability, plant type, anti-stripping agents, and moisture susceptibility .

INV_PMA _ROLLER: This table contains details on the rollers used to compact AC layers, including roller weight, tire pressure, and roller speed.

INV_SHOULDER: This table contains shoulder composition, geometric, and structural properties, including surface material type, width, thickness, base type, and associated details for PCC shoulders.

INV_STABIL: This table contains data on stabilizing agents used in base and subbase layers.

INV_SUBGRADE: This table contains available information on the properties of the subgrade from highway agency records, including plasticity indices, soil classification, soil strength, laboratory moisture-density relationships, in situ properties, soil suction, expansion index, frost susceptibility, and key gradation properties.

INV_UNBOUND: This table contains available information on the properties of base layers from highway agency records, including plasticity indices, classification, strength, laboratory moisture-density relationships, and in situ properties.

INV_DEICE_SITE_DATA: This table contains general information on snow removal and the frequency of deicer use. Data stored in this table are primarily for GPS test sections in the North Atlantic, North Central, and Western LTPP regions. Data were collected once at the start of the program in support of the SHRP research on snow and ice control.

INV_DEICE_TYPES: This table contains a listing of the type of deicers used on test sections. Data stored in this table are primarily for GPS test sections in the North Atlantic, North Central, and Western LTPP regions. Data were collected once at the start of the program in support of the SHRP research on snow and ice control.

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The Federal Highway Administration (FHWA) is a part of the U.S. Department of Transportation and is headquartered in Washington, D.C., with field offices across the United States. is a major agency of the U.S. Department of Transportation (DOT).
The Federal Highway Administration (FHWA) is a part of the U.S. Department of Transportation and is headquartered in Washington, D.C., with field offices across the United States. is a major agency of the U.S. Department of Transportation (DOT). Provide leadership and technology for the delivery of long life pavements that meet our customers needs and are safe, cost effective, and can be effectively maintained. Federal Highway Administration's (FHWA) R&T Web site portal, which provides access to or information about the Agency’s R&T program, projects, partnerships, publications, and results.
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