a Currently indoors only.

NCDC: National Climatic Data Center Service; NWS: National Weather Service.

A thorough record of the logistical data recorded during APT is essential for relating the test results to climatic regions, seasons, actual traffic, and environmental changes. The following data should be recorded during testing.

• Names of the staff involved in the test;
• Road number or location description (where tests are conducted on existing highways);
• Position on the road (in terms of distance beacons or other relevant parameters that are permanent features used in a geographic information system);
• Lane identification (inner/outer wheel track of slow/fast lane);
• Dimensions of the test section (length and width);
• Longitudinal and transverse crossfall or gradient;
• APT machine used (in terms of type of machine and serial number, if relevant);
• Start and finish dates;
• Type of trafficking mode used (e.g., uni-directional/bi-directional, channelized/wandering), together with details of the settings for obtaining the specific mode (where applicable);
• Trafficking speed and variability during trafficking;
• Trafficking cycles per day (e.g., 12-h trafficking with 12-h resting periods);
• Trafficking cycles per week (e.g., 5 days of trafficking with 2-day stoppages);
• Trafficking wheel load and tire inflation pressure;
• Measurement wheel load and tire inflation pressure (if not equal to trafficking wheel load);
• Wheel speed during measurements;
• Stoppages for repair or major maintenance;
• Tire type used (e.g., single/dual cross-ply/radial, automobile/aircraft);
• Contact stress pattern (if available);
• Pavement structure;
• Depth of water table and its variation during the test(s) with a description of methodology used;
• Material classification data as obtained through laboratory tests for the entire relevant pavement layers;
• Instruments used, and reference to their description and specification for use;
• Layout of positions on or in the pavement where instruments are placed;
• Environmental conditions (e.g., heated or cooled, water artificially applied or dry-tested), including pavement environmental parameters during the test (e.g., layer temperature and moisture content);
• Test program used;
• Extraordinary circumstances that might affect the outcome of the test;
• General weather conditions; and
• Number of load applications to date.

Surface deflection basins should be recorded at selected positions (transverse or longitudinal) on the test section with either a road surface deflectometer or a falling weight deflectometer, or both. In addition to the "general" data discussed above, the following should be recorded:

• Instrument used, with reference to description and specification for use;
• Resolution of the instrument used;
• Positional relation between the load applied and the measuring point;
• Units in which the measurement was made;
• Distance between points on the deflection bowl;
• Test wheel load, tire inflation pressure, and temperature at which the measurement was made;
• Positions at which the measurements were made;
• Number of repetitions of the same measurement, and
• Total number of measurements on the test section.

Elastic transient deflection and permanent deformation can be measured at predetermined depths by using linear variable differential transformer (LVDT) instruments (e.g., a device such as the multidepth deflectometer. The following should be recorded:

• Number and geometric positions of the LVDTs;
• Depths at which LVDTs were installed;
• Resolution of the LVDTs;
• Positional relation between the load applied and the measuring point;
• Units in which the measurement was made;
• Distance between points on the deflection bowl;
• Test wheel load, tire pressure, and temperature at which the measurement was made;
• Geometric positions at which measurements were made;
• Number of repetitions of the same measurement;
• Total number of measurements on the test section;
• Response measurements in terms of strains or loads (stresses where possible or applicable); and
• Any movement relative to a permanent immovable fixed benchmark, such as a permanent anchor buried 4 m deep.

Strain gauges and load cells can be used to measure pavement response under traffic loading. These may be installed during or after construction of the pavement. These devices are usually installed for special test sections and are generally not used for testing of in-service highways, with the exception of weigh-in-motion devices, which may be installed postconstruction. Response-measuring devices, such as strain gauges on axles, may also be installed on the APT machinery. The following should be recorded:

• Number and geometric positions of the response-measuring device(s);
• Depths at which response-measuring devices were installed;
• Positional relation between the load applied and the measuring point;
• Three-dimensional orientation of the installed device;
• Resolution of the device;
• Units in which the measurement was made;
• Test wheel load, tire pressure, and temperature at which the measurement was made;
• Geometric positions at which the measurements were made;
• Number of repetitions of the same measurement; and
• Total number of measurements on the test section.

The recording of visual information (degree and extent) is essential for obtaining the maximum benefit from APT. It may include some or all of the following:

• Transverse rutting;
• Longitudinal deformation;
• Surface crack growth;
• Bleeding of the surface;
• Raveling;
• Pumping;
• Potholing; and
• Surface wear.

Photographs may also be taken from preset fixed positions. The surface distress (cracking, bleeding, etc.) can be digitized to allow ease of data processing and exchange.

A cross section of surface rutting should be recorded at selected positions on the test section. The distance between readings on the cross section should be short enough to capture critical changes in the profile (less than 10 mm). The following should be recorded:

• Instrument used, with reference to description (infrared, laser, dipstick, other) and specification for use;
• Resolution of the instrument;
• Units in which the measurement was made;
• Distance between points on the cross-profile;
• Positions at which the measurements were made;
• Number of repetitions of the same measurement or the closure error if a topographic survey is used; and
• Total number of measurements on the test section.

A longitudinal section in the wheelpath should be recorded at selected positions on the test section. The distance between readings on the longitudinal section should be short enough to capture critical changes (normally 150 mm). The following should be recorded:

• Instrument used, with reference to description (infrared, laser, dipstick, other) and specification for use;
• Resolution of the instrument;
• Units in which the measurement was made;
• Distance between points on the longitudinal profile;
• Positions at which the measurements were made;
• Number of repetitions of the same measurement or the closure error if a topographic survey is used; and
• Total number of measurements on the test section.

The following weather data should be recorded:

• Ambient air temperature (every 15 min or other appropriate time intervals);
• Test-section temperature, measured by using thermocouples (every 15 min or other appropriate time intervals); and
• Rainfall (daily).

In characterizing the properties of the pavement materials, the following standard laboratory tests are typically performed and recorded:

Seals

• Aggregate hardness
• Binder type
• Aging index
• Description of the seal type and general condition

Asphalt (asphaltic mix)

• Grading
• Binder type and content
• Volumetric properties
• Indirect tensile strength
• Resilient modulus
• Dynamic creep modulus
• Superpave tests, such as dynamic shear rheometer, simple shear, frequency sweep, etc.
• Fatigue testing of beams or briquettes

Granular materials

• Grading
• Atterberg limits
• Cohesion and internal friction (where applicable)
• CBR

Material classification

• Resilient modulus
• Moisture/density relationship
• Cemented materials
• Unconfined compression strength (UCS)
• Material classification
• Type and content of stabilizer

Soils

• Grading
• Atterberg limits
• Cohesion and internal friction
• CBR

PART 3. VARIABLES OR ITEMS NOT COVERED IN THE SURVEY

The foregoing information needs to be reviewed and further critiqued by the Committee, APT respondents, and users. In addition the following items need further attention. Some items are simply requests for more information about APT programs and their data collection methods. Other items address the scope of this standardization effort.

• In measuring rutting, the length of the straight edge with which the ruts are being either measured or calculated needs to be ascertained. For example, the TxMLS uses the transverse profilometer data to calculate rut depth. Data covering a 1.2-m section is used to calculate the rut depth (or the raised upheaval) for each wheel path. The survey did not provide this important information.
• One survey respondent suggested gathering more information about the database structures. He suggests obtaining the following information: (a) whether the database management is manual or computerized; (b) if computerized, then what type of system (MAC, PC, other); and (c) the name of the computer software. The Committee needs to establish whether and to what extent the standardization effort will include database management.
• Details regarding the diagnostic trenching procedures and the data collection efforts should be provided.
• Details regarding testing of concrete pavements still need to be provided.
• Details regarding longitudinal profiles still need to be provided. The spacing between data points, as well as the locations of the profile measurements of various programs, needs to be examined.
• The importance of material testing and characterization cannot be overemphasized. APT users need to understand the important link between these and performance under APT trafficking.