Run a Roughness Report

Use the Roughness Report to obtain an indication of pavement roughness and how it affects the ride quality of the vehicle. The report obtains road profile information from imported .pav files and displays the IRI for points or segments along the alignment. The Roughness Index Report allows you to identify sections of the alignment that may require corrective action. The Roughness Index Report also calculates the smoothness of pavement using a Profile Index (PI) for the designed surface.

Prerequisites:

Licensed module; See the Subscription Plans page. For a license matrix by command, see the License page in the TBC Community. Also see View and manage licensed features.
Imported paving runs (.pav)
Alignment

To access the command:

Select Corridors > Roughness Report under Reports.
The Report View displays.

Options:

Reference alignment - In the Plan View or Project Explorer, pick the alignment for which the paving runs (.pav) were imported.
Objects - In the Plan View or Project Explorer, select the paving runs you want to generate IRI values for. It is not necessary to select an inside and outside wheel path pair as IRI values are computed for each wheel path.
Analysis type - Select the method required to report IRI:
- Overall - One IRI value is calculated over the entire run.
- Continuous: IRI values are generated for each measurement in the pav file.
- Fixed distance: IRI values are calculated across user defined segment lengths.
Segment Length - Type the distance you want the IRI calculated over. The segment length will affect the IRI value as it determines the amount of data that is averaged.
Note: The distance between measured sample points may not exactly align with the segment length specified. The report will use the sampled points that are closest to the segment length.
If you selected Overall or Continuous as the analysis type this field is not applicable.
Only include subsection - Check this box to specify a station range to report on. Type the start station and end station. Use this option when continuous is selected to avoid reporting on every measurement in the road profile.
Note: A sample may not have been taken at the specified start station. The report will start at the sampled station that is closest to the start station.

International Roughness Index

Threshold - Select the maximum acceptable IRI for the pavement.
If you selected Overall as the analysis type, this field is not applicable.
Apply Filter - Check this box to eliminate spikes from loose rocks on the surface. Type the filter size.

Profilograph Index

Blanking band - Specify the width of the blanking band used to dismiss small deviations in the profile trace.
Minimum scallop width - Specify the smallest allowable scallop width (outside of the blanking band) on the trace of the profile.
Minimum scallop height - Specify the smallest allowable scallop height (outside of the blanking band) on the trace of the profile.

Scenarios:

If Overall is selected as the analysis type the report generated shows the overall roughness index.
If Continuous is selected as the analysis the report shows a line graph representing the IRI value at each measurement point along the alignment. The red line is the maximum allowable IRI value for the pavement as specified in the Threshold field. You can view the points on the alignment where the threshold is not achieved. In the Defects section IRI values are reported for stations which above the threshold.
If Fixed distance is selected as the analysis the report shows a bar graph with intervals specified by the segment distance. In the Results section IRI values are reported for all segments. Segments with IRI values above the threshold are displayed in red.

Note: the IRI value is displayed in m/km or inches/mile depending on the distance setting in the Units group in Project settings.

Example

A paving run file has been recorded and imported into a Trimble Business Center project. A Roughness Index Report has been run over a fixed distance of 528 ft. Most of the segments have an IRI value below the threshold specified. One segment has an IRI value above the threshold. To determine the stations that are causing the high IRI value, run another roughness report selecting continuous as the analysis type. Type the station range for the segment with the high IRI value. The report will display the individual IRI values at each measurement point. The stations where the IRI value is above the threshold are shown in red. Look for large spikes that may be causing the high IRI value. Corrective action may be required at these stations.