DETERMINING PAVEMENT RIDE QUALITY

SCOPE

This IM describes procedures used to perform smoothness testing on new pavements surfaces. A certified person is required to perform the testing, evaluation, and reporting.

PROCEDURE

A. Apparatus

1. Inertial Profiler meeting the requirements of AASHTO M328 (this requires an auto start/stop) and currently certified on the Iowa DOT test strips or other state test strips approved by the Iowa DOT. For all surfaces other than dense graded HMA, a large footprint laser is required.

2. Ten-foot straight edge or a 10-foot straight edge software simulation.

3. Distance measuring wheel or tape.

4. Latest version of ProVAL software. http://www.roadprofile.com/proval-software/current-version/

5. Latest version of the Iowa DOT Spreadsheet, Profile Summary Sheet and the current ProVAL template.  https://iowadot.gov/construction_materials/Materials-forms

B. Profiler Approval

1. All profilers must be checked and approved by the Iowa DOT Materials Laboratory before each construction season for proper operation.  Profilers checked and approved in another state in the current year may be approved.  Submit a request to Special Investigations Engineer for consideration of approval.

2. ProVAL will be used to analyze the profiler files. The criteria for approval includes:

a) High pass and low pass filters set to 0. All other settings according to manufacturer’s recommendation (The settings used for approval will be the same used throughout the season).

b) Submittal of 5 good runs of the test strip as ProVAL readable files.

c) The DMI distance shall be within 0.15% of the actual test strip distance.

d) The equipment repeatability score with the IRI filter shall be 0.90 or greater.

e) The equipment accuracy score with the IRI filter shall be 0.88 or greater when compared to the reference profiler.

f) The average IRI shall be within 5% of the reference profiler IRI.

C. Calibration and Verifications

Checks, calibrations, and verification of subsystems vary by manufacturer. Follow the manufacturer’s recommended procedures and frequencies to ensure proper profile collection.

D. Test Procedure

1. The contractor (or sub-contractor) responsible for smoothness testing shall give the Project Engineer and the District Materials Engineer 48 hour notice prior to testing so the District Materials Office may provide verification testing.

2. Dirt and debris may affect collection of the profile. Excessive mud or caked mud must be removed prior to testing. A grader blade or power broom will knock concrete crumbs off longitudinal or transverse grooving.

3. Perform the warmup and checks of the profiler.

a) For most profilers, the tire pressures should be maintained at the same pressures as when the distance was last calibrated.

b) It is advisable to do a bounce test and vertical height test on the sensors before beginning testing.

4. Ensure computer settings are the same as when the unit was approved by the DOT.  The high-pass and low pass filter settings should be “0”.

5. Test in the direction of traffic whenever possible.

6. Test unit positioning.

a) Testing is to be done with the sensors in the wheel paths, 3 feet and 9 feet from the centerline or lane line, for lanes 11 feet to 12 feet wide unless noted otherwise in the contract documents.

b) For testing on wider lanes such as ramps and loops, position the driver side sensor 3 feet from the left edge line.  If the passenger side sensors is within 1 foot of a longitudinal joint.  Adjust the travel path to the right so the sensor is 2 feet from the joint line.

c) For testing tapers to and from a full lane, begin or end the section testing when the pavement is either 12’ or at the full lane width whichever is less.

d) Begin collecting profile data for ALR 50’ before the beginning header from old to new surface and 50’ beyond the header from new to old surface. Figure 1

e) Figure 2 and 3 show examples of how to analyze ALR at obstructions defined in 2317.03,B,2,b.

7. Ensure there is enough room before and after the section to be tested to allow for a 300 foot run-in and run-out area for the profiler before and after the test section according to the manufacturer’s recommendations.  The run-in allows the accelerometers, lasers, and computer to stabilize before the start of the section. Mark the intended start and stop location of the section and place reflective cones or strips to trigger the auto start/stop sensor on the profiler.

8. Use the event feature to mark on the file any reference points like, side road intersections, roadway signs, maintenance markers, stations markers, and mileposts. In the event of rough segments or ALR, this will help the grinding personnel locate the area to grind. (The as driven stationing from the profiler will rarely match the stationing on the roadway unless the roadway is completely flat with no curves.  The longer the run of the profiler, the farther the profiler stationing will be off from the plan stationing.)

9. During the profiler run, use the ignore feature at bridges and bridge approaches to mark areas on the file and exclude the data from the analysis.  The profiler still collects data and it can be recovered later during analysis if the key is pressed inadvertently.

10. Label the file so it can be easily found and retrieved later. (Project number, lane, and beginning station in the file name is one way to label)

11. When a segment is corrected by grinding to improve the segment MRI, the entire segment must be retested and a MRI determined to verify that the corrected segment is in specification compliance.

E. Analyzing and Reporting

1. Use the profiler software export function to export an unfiltered “ERD” file or use any other unfiltered ProVAL readable file.

2. Use the latest version of ProVAL to perform the MRI and ALR analysis on the files.

3. Report results on the DOT provided Excel spreadsheet (Figure 4).The sheet can be downloaded at https://iowadot.gov/construction_materials/Materials-forms. The test report is required on this form for project acceptance.

4. Any areas needing correction will be noted by the software on the spreadsheet. For segments that are ground to correct the MRI, show the corrected MRI and mark the box to the left of the segment to show grinding has been completed on that spreadsheet.

5. There are three types of reports:

a) Preliminary.  Used by the contractor to submit the report in the time period required in the specifications.  A final report must follow.

b) Final.  Used to indicate that the report is being submitted for acceptance.

c) Corrected.  Used to indicate that there was either an error in the original test report or that the section was corrected by grinding and retested.

6. Test report laboratory numbers must be continuous and increasing numerically as each succeeding test is performed. Laboratory numbers shall have a letter added to the end of the original laboratory number for corrected reports (i.e., original report number 01-218L-05, corrected report number 01-218L-05-A).

7. Submit all final and corrected reports to the engineer through DocExpress.  If the smoothness testing is done after the paving is completed, submit the ProVAL file(s) to DocExpress also. Label the ProVAL file(s) with the project as part of the file name.

8. Keep all ProVAL files not submitted to DocExpress until validation of the contractor test results has been confirmed.

9. An example of a completed report form is shown in Figure 4.

F. Certification

Use a trained, certified person to do the testing, evaluation, and reporting. The certification information is in Materials IM 213.

VALIDATION OF CONTRACTOR TEST RESULTS

In order to use the Contractor test results in the acceptance decision, the results must be validated. 

Normally the District Materials Office will perform verification testing within 1 month from receiving finals test reports and notification from the Contractor that the pavement is available for testing.  The validation tolerances are in IM 216.

When the Contractor test results cannot be validated, the District Materials Office will promptly notify the Contractor and begin the dispute resolution process. Testing disputes arising between the Contracting Agency and the Contractor shall be resolved in a reliable, unbiased manner. This may involve an evaluation performed by the Iowa DOT Central Materials Laboratory. Resolution decisions by the Iowa DOT Central Materials Laboratory will be final.

The District Materials Engineer will select some or all of the following steps for the dispute resolution:

1. Check all numbers and calculations.

2. Review testing procedures.

3. Compare profiles and dates of testing.

4. Check equipment operation, calibrations and tolerances.

5. Perform side-by side tests.

6. Involve the Central Materials Laboratory.

If the discrepancy cannot be resolved using the steps listed above, or if it is determined that the Contractor’s testing is in error, then the Agency test results will be used for the acceptance decision for the project.

Figure 4. Standard Spreadsheet for Reporting Results