Long-Term Pavement Performance Ohio SPS-1 and SPS-2 Dynamic Load Response Data Processing

8. UPDATES TO THE OHIO SPS-1 AND SPS-2 DLR TABLES

This chapter summarizes the key updates made to the Ohio SPS-1 and SPS-2 DLR tables in SDR 27.0.⁽¹⁾ The following updates were made to the five trace tables:

• A new gain adjust factor (average of the first 500 trace data points) column was added. A gain adjustment factor was subtracted from each raw trace data point to generate a normalized trace base zero on the y-axis-that is, under no load conditions-so that the resulting peak values represented the change due to load response. For the SPS-1 data, normalized raw or smoothed traces were used to extract the trace peaks and valleys. For the SPS-2 data that had significant noise in the raw traces, only normalized smoothed traces were used to extract the trace peaks and valleys even though the gain adjustment factor was determined using the raw trace data.
  
  
• A new data collection frequency column was added for the frequency at which the trace data point was collected by the corresponding sensor identified by the tag ID (sensor ID) field.
  
  
• For the SPS-1 data, TIME_RAW_* (timestamps) and STRAIN/LVDT/PRESSURE_VALUE_RAW_* (trace peak and valley location values) were updated using the data extracted from SPS-1 normalized raw traces.
  
  
• Also for the SPS-1 data, TIME_SMOOTH_* (timestamps) and STRAIN/LVDT/PRESSURE _VALUE_SMOOTH_* (trace peak and valley location values) were updated using the data extracted from SPS-1 smoothed traces.
  
  
• For the SPS-2 data, TIME_RAW_* and STRAIN/LVDT_VALUE_RAW_* columns were removed from the DLR database because the SPS-2 raw traces were too noisy to extract any meaningful peaks and valleys.
  
  
• Also for the SPS-2 data, TIME_SMOOTH_* (timestamps) and STRAIN/LVDT _VALUE_SMOOTH_* (trace peak and valley location values) were updated using the data extracted from SPS-2 smoothed traces.

In the five configuration tables, the following updates were made:

• Initially, some newly added SPS-1 and SPS-2 tests had missing sensor calibration information such as channel number, record status, input card, card gain, post gain, and gauge resolution. By matching State code, SHRP ID, and Tag ID (sensor ID) of existing tests that had sensor calibration information, those tests that had missing information could be populated regardless of test names.
  
  
• The sensor locations in terms of X, Y, and Z coordinates were updated using the X, Y, and Z data by matching section ID and sensor ID.
  
  
• The sensor layer number column was updated using the Z (sensor depth in inches) data and the layer column.
  
  
• The strain gauge orientation column in the DLR_STRAIN_CONFIG_AC/PCC tables was updated using the DirCosX (1 for longitudinal) and DirCosY (1 for transverse) data.

In the DLR_TEST_MATRIX table, the following updates were made:

• Run time (the time of the test as determined by the data acquisition computer's internal clock) was updated using the timestamp in cell A3 of each AJ*.* raw trace file by matching STATE_CODE, SHRP_ID, TEST_NAME, and RUN_NUMBER.
  
  
• Revision date (Date of latest revision to the information stored in the DLR_TEST_MATRIX table) was set to August 24, 2012, the date when the DLR study team submitted the newly created SPS-1 and SPS-2 DLR database.
  
  
• Actual speed (actual speed of the test truck) was newly added and populated using the Speed data in TruckPass.txt. The DLR study team believed that this column, in addition to the desired speed column, will provide valuable information for data users when interpreting DLR traces.
  
  
• WHEEL_PATH_OFFSET1_M (distance from the edge of pavement to the outside of the front tire track for OH data) was updated using the OFFSET1 data in TruckPass.txt.
  
  
• WHEEL_PATH_OFFSET2_M (distance from the edge of pavement to the outside of the rear tire track for OH data) was updated using the OFFSET2 data in TruckPass.txt.
  
  
• WHEEL_PATH_OFFSETX1_M (distance along the direction of traffic as referenced from the start of the southernmost first LVDT in the section to the location where the front axle wheelpath offset was measured) was newly added using the OFFSETX1 data inTruckPass.txt.
  
  
• WHEEL_PATH_OFFSETX2_M (distance along the direction of traffic as referenced from the start of the southernmost 1st LVDT in the section to the location where the rear axle wheelpath offset was measured) was newly added using the OFFSETX2 data in TruckPass.txt.
  
  
• When comparing the DLR_TEST_MATRIX table in SDR 22.0 to the five trace tables, the DLR study team found that 9 of the 724 records in DLR_TEST_MATRIX did not have any source data to populate the following columns: ACTUAL_SPEED, WHEEL_PATH_OFFSET1_M, WHEEL_PATH_OFFSET2_M, WHEEL_PATH_OFFSETX1_M, WHEEL_PATH_OFFSETX2_M, and MATRIX_INDEX. Consequently, the nine records, which are listed in table 23, were removed and are not in the final DLR_TEST_MATRIX table in SDR 27.0. 

Table 23 . Records in the DLR_TEST_MATRIX table in SDR 22.0 with no source data.

Run 1 of test J10E in table 23 is an example of a missing record. The available records in TruckPass.txt for run 1 are listed in table 24. Test section 390110 (test J10E run 1) is not on the list. Because the nine records in table 23 were removed from the DLR_TEST_MATRIX table, 54 traces that did not have a matching record in the DLR_TEST_MATRIX were removed from the 5 trace tables in SDR 27.0.⁽¹⁾

Table 24 . TruckPass.txt records for run 1.