Detecting and Correcting Localized Roughness Features

Transcription

1 0 0 Detecting and Correcting Localized Features Gary J. Higgins Earth Engineering Consultants, LLC Greenfield Drive Windsor, Colorado 00 Tel: 0--0; Fax: 0--0; garyh@earth-engineering.com Word count:, words text + tables/figures x 0 words (each) =, words August, 0 (Revised November, 0)

2 Higgins 0 0 Abstract Data collected by inertial profilers on new asphalt pavements in Colorado in 0 were used to analyze the effectiveness of the localized roughness specification in Colorado. For the analyzed projects, data was collected before any corrections were made as well as after diamond grinding had been performed to remove areas of localized roughness. The data indicated that localized roughness features having a Half Car Index (HRI) below in/mi are rarely addressed during correction. However, about half of the localized roughness features that have an HRI to 00 in/mi are being successfully addressed during correction. Localized roughness features having an HRI over 00 in/mi appear to be successfully addressed during correction. The analysis indicated there is a significant difference in the localized roughness locations identified by AASHTO specification R () and the Colorado Department of Transportation (CDOT) method of detecting localized roughness. Where the CDOT procedure specifies a minimum length for a roughness feature that is to be corrected, AASHTO R does not. This paper shows collecting accurate profile data and analyzing the data to determine localized roughness locations is not enough. The identified locations must be correctly marked on the pavement in the field to eliminate the feature causing the localized roughness. This paper presents a procedure for not only collecting accurate data but also to accurately mark the roughness features in the field, and shows that it is possible to accurately locate and correct localized roughness to the current thresholds as set by AASHTO R. Keywords: Smoothness, Localized, Areas of Localized Detection, Quality Control (QC)

3 Higgins INTRODUCTION The Colorado Department of Transportation transitioned from a California profilograph smoothness specification to an inertial profiler smoothness specification. With this transition, reported smoothness data changed from the profile index (PI) to the international roughness index (IRI). Both of these indices measure and report the smoothness data in each wheel path and both indices can be used to locate areas of imperfection within the roadway causing objectionable ride quality, however, in two very different ways. Swan and Karamihas report in Use of a Ride Quality Index for Construction Quality Control and Acceptance Specifications () that the California profilograph measures smoothness by accumulating surface deviations from a short planar surface and the IRI measures smoothness by passing a vehicle over the road profile to measure roughness that causes vehicle vibrations. Swan and Karamihas () also state that these two measurement approaches are rarely sensitive to the same surface deviations and are not compatible. The Colorado PI specification measured the accumulation of surface deviations in each wheel path and reported in inches/mile readings for each one-tenth mile segment of new pavement with a California type profilograph operating at a maximum speed of miles per hour (mph). Areas of localized roughness, bumps, or dips were identified by any surface deviation greater than two-tenths of one inch. The method for locating on the pavement surface areas of defined localized roughness was to return to location using stationing numbering and place a tenfoot straight edge on the pavement. The area of localized roughness would be the area having the greatest surface deviation as displayed with the straight edge. This area would then be diamond ground to remove the large surface deviation. The IRI specification in Colorado uses the inertial profiler operating at or near the posted speed limit, up to 0 mph. The inertial profiler measures surface deviations causing vehicle vibrations, i.e. roughness in the roadway, and reports roughness in inch/mile readings for each one-tenth mile segment of new pavement. Areas of localized roughness are identified by surface deviations causing vehicle vibrations over a set threshold using the US FHWA sponsored Profile Viewing and Analysis (ProVAL) () software as per CDOT Specification 0.0 Conformity to Roadway Smoothness Criteria of HMA (). The method for locating, on the pavement surface, areas of localized roughness requires additional ProVAL analysis to determine the exact location of each of the identified disturbances. This additional ProVAL analysis will give the exact location of the roadway feature causing the unwanted vehicle vibrations, which may or may not be the greatest area of vertical surface displacement. ProVAL will also predict whether the feature can be corrected by diamond grinding and will specify the exact start and stop location for grinding which is necessary to correct the roughness. The specified locations from the ProVAL software program must be correctly identified on the pavement surface for diamond grinding to correct the deficient area. A study was performed to assess the effectiveness of the CDOT localized roughness specification.

4 Higgins SMOOTHNESS SPECIFICATIONS AASHTO R-0 Localized roughness is defined as any foot segment of roadway that contributes disproportionately to the overall roughness index. Areas of localized roughness are identified using a report of continuous IRI with a base length of feet. Any segment where the continuous report exceeds a threshold value is considered a defective segment requiring correction. Typical threshold values are stated to range between IRI values of 0 to 0 in/mi, 0 to 0 in/mi, and 0 to 0 in/mi depending on whether the roadway is interstate, state primary, or state secondary roadway, respectively. CDOT Colorado specifies the half-car roughness index (HRI) be used for reporting smoothness data. The HRI reporting averages the left and right inertial profile points (left and right wheel path), point for point for every given distance value then runs the averaged profile through the IRI algorithm. The IRI is known as the quarter-car roughness index and reports each wheel path separately thus producing both left and right wheel path ride numbers for each segment. An approximate conversion from IRI to HRI is stated by Sayers and Karamihas in The Little Book of Profiling () as HRI = 0.*IRI. The specific relationship is site specific, however, HRI will always be less than IRI. Colorado specifies HRI be reported in inches/mile reading for each onetenth mile segment of new pavement in addition to a localized roughness specification. Incentive or disincentive payment is calculated for each tenth-mile segment or fraction thereof only. Corrective action on any tenth-mile segment is mandatory if the HRI exceeds the project specific threshold values. Areas of localized roughness with an HRI over a project specific threshold, and also greater than.0 feet in length, shall be considered deficient and mandates corrective action of the specific localized roughness feature. Corrective action (diamond grinding) is specified to the entire lane width with the HRI reporting. CDOT specification requires ProVAL software be used for the determination of localized roughness. Areas of localized roughness are defined where the HRI readings are above in/mi to 0 in/mi, depending on project specification, and greater than feet in length, as indicated on the ProVAL report of continuous ride quality using an averaging length of feet. The report of continuous ride quality indicates where the ride quality is above the CDOT defined threshold of localized roughness. This report does not indicate where diamond grinding should be conducted on the pavement surface to eliminate the localized roughness. The method for identifying areas of defined localized roughness on the pavement surface for corrective action requires the use of the ProVAL Smoothness Assurance Modular (SAM). The specific project parameters for localized roughness, the maximum depth of allowed grinding, and the specific grinder configuration are used as input parameters to SAM.

5 Higgins FIGURE Typical SAM Grinding Inputs Figure displays a typical set up for creating grinding strategies with the ProVAL software. A grinding strategy is necessary for locating the exact areas on the pavement surface where diamond grinding would eliminate or improve areas of defined localized roughness. The specific grinder type that will be utilized on the project should be selected. If given exact specifications on the grinder head position, wheel base, and tandem spread, enter information in the appropriate locations. If only the grinder type is known, use the default settings under the grinder type. The basic grinding strategy is defined as a single pass in the forward direction with a zero head height at the start. The owner-agency may specify a limit on the depth of grinding, if so enter value into the maximum grinding depth column. ProVAL will only give a warning message when the depth of predicted grinding will exceed the user set limit and will apply the deep grind. However, in deep grind areas the operator of the grinder will only remove material up to the maximum depth as stated in the jurisdictional specification. Because of this difference, it should be expected that predicted results will reflect better ride quality than actual ride quality results for areas defined by ProVAL as deep grinding and where the owner-agency specifies a maximum depth of removal. With the project specific parameters set in SAM, the profile data can be analyzed to determine the effectiveness of the grinding process. The Auto Grind feature in SAM is used to produce a template for grinding. The Auto Grind will identify every area where grinding could be considered to yield an overall smoother riding surface regardless of specified threshold values. Unselect all grind locations and view the filtered profile in the Short Continuous display where the ride quality graph can be compared to the elevation profile. Areas of localized roughness rise above the set threshold line on the top graph and the roadway elevation profile is displayed in the bottom graph. Simultaneously viewing the ride quality graph with the elevation profile allows a means to quickly determine what type of defect - bump or dip - is causing roughness on the roadway. A filtered elevation profile removes grade and pavement texture from the profile while retaining the roadway characteristics responsible for ride quality. Therefore, the filtered elevation profile with respect to the specific features causing roughness should accurately be depicted as bumps or dips on the elevation profile. The filtered elevation profile will not match exactly the visible roadway because the grade has been removed by filtering, however, the specific undulating roadway surface pattern at each specific area of localized roughness has been retained within the filtered profile. Therefore, the specific undulation pattern at an area of

6 Higgins roughness is visible on the roadway surface. It is this pattern, visible on the roadway surface, that the experienced operator can use as confirmation that the roadway area matches the ProVAL simulation area. FIGURE SAM Grinding Simulation: Short Continuous 0 Figure shows the ride quality profile on the top graph and the elevation profile trace in the lower graph. The threshold value for localized roughness is set at HRI and is represented by the horizontal red line on the top graph, ride quality exceeding this value is considered localized roughness. The short continuous ride quality graph (top) displays a foot long area in violation of the set threshold and the exact location is shown within the circled area on the summation table to the left of the graph. However, this is not the location which will be located on the roadway for grinding. To determine the exact location for grinding on the roadway, one must navigate to the grinding page of SAM and select from the user created auto grind list as displayed in Figure below.

7 Higgins FIGURE SAM Grinding Simulation: Grinding Figure displays the grinding page within SAM. The exact area for locating and marking for grinding on the roadway surface is determined on the grinding page. The short continuous ride quality graph displays a foot long area of roughness. The grinding page determines that this area of roughness is a bump and can be eliminated with a foot long, single pass in the forward direction, zero head height grind. The location of this grind, from 0, feet to 0,0 feet, should be identified on the roadway surface for grinding. It is required that this sequence be followed for each area identified over a set localized roughness threshold as the locations determined on the Grinding page will be the exact areas to locate on the roadway for diamond grinding. The experienced user will understand that some areas of localized roughness cannot be corrected and some areas could be made worse with grinding. Only by consulting the ProVAL after grind simulation graphic can it be determined where each specific grind should start and stop to improve the ride quality. The locations selected from SAM for diamond grinding must be located on the pavement surface for the completion of grinding. Accuracy at locating on the pavement surface, the defined areas for corrective work is critical to the success of the grinding operation and critical to matching the predicted ProVAL SAM results. DATA FOR ANALYSIS To assess the Colorado localized roughness specification, inertial profiler data was requested and obtained from CDOT. The obtained data was limited to inertial profiler data which was submitted to or collected by CDOT on new or newly rehabilitated asphalt pavement projects, with the profile data consisting of data collected before any corrections were made to the surface and data collected after corrections were made with grinding. CDOT provided lane miles of profile data meeting the criteria which was collected during the 0 paving season and the data was from various projects and collected by various Colorado certified inertial profiler units operated by certified operators. No attempt was made to specifically identify projects, inertial profilers, or operators and no data from Earth Engineering Consultants, LLC is included in this data set. CDOT also provided the localized roughness reports generated for each project, from both before and after grinding operations.

8 Higgins DATA ANALYSIS To assess the effectiveness of the grinding operations, the before grinding profiles were analyzed with the ProVAL SAM Software tool. These profiles were run through ProVAL s SAM module using AASHTO R () specification and then again using CDOT Specification 0.0 Conformity to Roadway Smoothness Criteria of HMA () for localized roughness thresholds for each individual project. The objective of the analysis with the two different specifications, CDOT and AASHTO, is to highlight: a) the effect a minimum length requirement has on defined localized roughness features, and b) to show it is possible to correct localized roughness as defined by the more stringent AASHTO R which does not specify a minimum length requirement. The foot grinder was selected with ProVAL default settings and applied to all grinding simulations. The ProVAL SAM results are assumed to be the maximum theoretical effectiveness for corrective (grinding) results. CDOT also provided the after grinding localized roughness report for each project. The actual project results were then compared to the ProVAL predicted results to determine the effectiveness of the project grinding efforts. Table displays the ProVAL SAM prediction for correcting localized roughness compared to the 0 Colorado asphalt paving projects success at correcting localized roughness. As the ProVAL SAM results indicate, all localized roughness features cannot be corrected with diamond grinding. Several factors influence the grinding effectiveness: a) CDOT specification limits the depth of material removal to 0.0-inch; b) specific roughness feature does not allow contact with the cutting drum of grinder with the roadway; c) roughness is improved but still over threshold (this situation may occur due to a single grinding pass, where adjusting the head depth slightly downward can significantly improve the ride quality, however, removing 00% of material in a given grind length, for a single pass grind will not improve ride quality); d) roughness incorrectly located on the pavement for corrective action. Column : Represents the HRI grouping selected for analysis. Column : Displays the count of areas of localized roughness, prior to correction, based on AASHTO R specification for the lane miles of CDOT data. Column : Displays the count of areas of localized roughness remaining, after project grinding, based on AASHTO R specification for the lane miles of CDOT data. Column : Displays the predicted count of areas of localized roughness remaining after running the ProVAL SAM simulated grinding analysis. Column : Percent of areas of localized roughness improved by project grinding efforts. Column : Percent of locations that ProVAL SAM indicates could be improved with grinding based on simulation.

9 Higgins 0 0 TABLE - 0 Colorado Asphalt Paving Projects Success at Correcting Localized Compared to the ProVAL SAM Software Prediction for Correcting Localized Based on AASHTO R Definition Localized Threshold Grouping HRI Range (in/mi) Deficient Locations from Uncorrected Profile Deficient Locations after Project Grinding Deficient Locations after ProVAL SAM Simulated Grinding Locations Improved Based on Project Data (%) to 0 0% % 0 to 0 % % to 00 % % Over 00 0% % Total 0 % % ProVAL SAM Predicted Locations Improved (%) As Table indicates, localized roughness with an HRI between in/mi to 0 in/mi showed only 0% of the locations were improved, where the ProVAL prediction was % should have been improved. For HRI between 0 in/mi to in/mi actual data showed only % of the locations were improved, where the ProVAL prediction was % should have been improved. For HRI between in/mi to 00 in/mi actual data showed only % of the locations were improved, where the ProVAL prediction was % should have been improved. For HRI over 00 in/mi actual data showed 0% of the locations were improved, and the ProVAL prediction was % should have been improved. The results indicate localized roughness below an HRI of 00 in/mi are problematic for corrective action. A portion of the discrepancy between the results obtained from actual data collected in Colorado and simulated results obtained by ProVAL s SAM module can be explained by the procedures indicated in Colorado s smoothness specification. Starting in 0, the CDOT definition of localized roughness states areas of localized roughness greater than.0 feet shall be considered deficient, and require corrective work ().The effect on areas of localized roughness when the specified longitudinal minimum distance is applied is shown (Table ). TABLE - Effect on Areas of Localized When a Longitudinal Minimum Distance of is Applied Localized Threshold Grouping HRI Range (in/mi) Deficient Locations from Uncorrected Profile No Minimum Length of Deficient Locations from Uncorrected Profile ft Minimum Length of to 0 % 0 to 0 % to 00 0% Over 00 0% Total 0 % Reduction in Defined when ft Minimum Length of is Applied (%)

10 Higgins As Table shows, almost all of the features in the HRI range of in/mi to 0 in/mi category appear to be short duration ride quality violations (i.e., length of unacceptable vehicle vibration causing the localized roughness threshold to be violated is less than feet) but still defined as areas of localized roughness per AASHTO R which has no minimum length requirement. Because of the CDOT requirement that the localized roughness threshold must be violated for a minimum of longitudinal feet to require corrective action, the locations for corrective action drops from locations to only locations requiring corrective action between HRI of in/mi and 0 in/mi. In addition to the % reduction of defined localized roughness between HRI of in/mi to 0 in/mi, a % reduction of defined localized roughness between HRI of 0 in/mi to in/mi is observed. The 0 CDOT data set, for both actual results, ProVAL predicted results, and removing localized roughness features which are.0 feet in length or less, as specified in the 0 CDOT specification applicable at the time this data was collected is summarized (Table ). Column : Represents the HRI grouping selected for analysis. Column : Displays the count of areas of localized roughness, prior to correction, based on CDOT specification 0.0 for the lane miles of CDOT data. Column : Displays the count of areas of localized roughness, after correction, based on CDOT specification 0.0 for the lane miles of CDOT data. Column : Percent of areas of localized roughness improved by project grinding efforts. Column : Percent of locations that ProVAL SAM indicates should be improved with grinding based on simulation. TABLE 0 Colorado Asphalt Paving Projects Success at Correcting Localized Based on 0 Colorado DOT Specification Defining a Minimum Length of Localized Localized Threshold Grouping HRI Range (in/mi) Deficient Locations from Uncorrected Profile ft Minimum Length of Deficient Locations from Corrected Profile ft Minimum Length of Locations Improved Based on Project Data (%) to 0 % % 0 to 0 % % to 00 % % Over 00 % % Total % % ProVAL SAM Predicted Locations Improved (%) Table displays the effectiveness at addressing localized roughness based on the 0 CDOT specification. Localized roughness HRI between in/mi to 0 in/mi actual data showed only % of the locations were improved, where the ProVAL prediction was % should have been improved. For HRI between 0 in/mi to in/mi actual data showed only % of the locations were improved, where the ProVAL prediction was % should have been improved. For HRI between in/mi to 00 in/mi actual data showed only % of the locations were improved, where the ProVAL prediction was % should have been improved. For HRI

11 Higgins over 00 in/mi actual data showed % of the locations were improved, and the ProVAL prediction was % should have been improved. The results indicate localized roughness below an HRI of 00 in/mi are problematic for corrective action even after a large percentage of localized roughness is removed by Colorado specification language. DETAILED PROJECT LEVEL ANALYSIS Data collected on lane miles of an interstate project where a new asphalt pavement was built was analyzed to study the issue of localized roughness. The data was collected by Earth Engineering Consultants, LLC in 00 and 00. CDOT specification 0.0, at the time this project was completed, did not specify a minimum longitudinal length to the definition of localized roughness. The collected data was submitted to CDOT. Thereafter, a grinding strategy was generated by Earth Engineering Consultants personnel using ProVAL SAM to determine the grinding limits necessary to remove the identified localized roughness features on the pavement surface. The input parameters for SAM analysis included an -foot grinder using the ProVAL default grinder configuration. The ProVAL SAM suggested grinding locations were then identified and marked with paint on the pavement surface in the field. Upon completion of the locating and marking on the pavement surface, the -foot diamond grinder was directed to grind, within the paint markings, the entire lane width per CDOT specification. Inertial profiler data was then collected after grinding. This data was compared in similar fashion as described previously to determine the effectiveness of the project grinding efforts. Tabular results of the lane miles of data showing effectiveness at correcting localized roughness based on 00 CDOT definition, having no specified minimum length for defined areas of localized roughness are shown (Table ). Column : Represents the HRI grouping selected for analysis. Column : Displays the count of areas of localized roughness, prior to correction, based on 00 CDOT specification 0.0 for the lane miles of Earth Engineering Consultants data. Column : Displays the count of areas of localized roughness, after correction, based on 00 CDOT specification 0.0 for the lane miles of Earth Engineering Consultants data. Column : Percent of areas of localized roughness improved by project grinding efforts. Column : Percent of locations that ProVAL SAM indicates should be improved with grinding based on simulation.

12 Higgins TABLE Tabular Results of Actual and Predicted Effectiveness at Correcting Localized of the Approximate Lane Miles of Data Provided by Earth Engineering Consultants, LLC Showing Success at Correcting Localized Based on 00 CDOT Definition Localized Threshold Grouping HRI Range (in/mi) Deficient Locations from Uncorrected Profile Deficient Locations from Corrected Profile Locations Improved Based on Project Data (%) to 0 0 % % 0 to % 0% to % % Over 00 0 % % Total 0 % % ProVAL SAM Predicted Locations Improved (%) The results of grinding effectiveness for this project indicates very good correlation with actual results and ProVAL SAM predicted results, correcting % of the defined areas of localized roughness at or below an HRI level of in/mi level. Obtaining 00% correction of localized roughness at or below an HRI level of in/mi level may not be possible due to the fact that a portion of the HRI features over the 00 in/mi threshold, when diamond ground, are improved but not fully corrected. Therefore, a portion of these larger features shift towards a smaller HRI but still over a threshold. The localized roughness features over HRI in/mi threshold exceed the ProVAL SAM prediction, possibly due to the grinder operator increasing the head depth at the start of the grind and the ProVAL simulation head depth was run at a zero depth. Overall, the results indicate that localized roughness can be successfully identified on the pavement and corrected with traditional methods (grinding) and that ProVAL SAM provides an accurate grinding strategy. DISCUSSION OF RESULTS The data obtained from CDOT that was described previously was collected by CDOT certified equipment of different makes and models operated by CDOT certified operators. The equipment and the operators have all passed the various Colorado required certifications and therefore all should produce similar results. However, when results from the CDOT provided data are compared to the results from Earth Engineering Consultants data, it becomes evident that operators who are following a procedure for identifying defined localized roughness on the roadway surface produce results much closer to the ProVAL predicted results for corrective action with diamond grinding. As the above data comparison indicates, a procedure to accurately locate on the pavement surface areas of localized roughness is not only feasible but is in use, by some, at the project level as illustrated by the data provided for the lane mile project. This procedure requires no additional equipment. However, it requires a grinding strategy, which will indicate the type of defect, bump, or dip, to aid in visual identification of the roughness feature on the pavement causing the localized roughness (from grinding strategy), and identifying with markings (paint) on the pavement the limits for performing the diamond grinding to remove the roughness feature.

13 Higgins After the initial smoothness data has been collected, analyzed, and a grind strategy has been formulated, the distance measuring instrument (DMI) in the inertial profiler used on the project to collect the initial data should also be used to mark areas of localized roughness. Although ProVAL software will simply convert the DMI numbering system into stationing numbering, this should be avoided because some low threshold localized roughness violations may be incorporated within a series of small pavement fluctuations. Therefore, the accuracy of the DMI would be needed to pinpoint the exact location of the specific feature to be ground. The operator must be aware of the capability of the specific DMI system in use on the inertial profiler vehicle. Some DMI device models may not operate correctly in a stop and start manner and the operator may need to compensate for the effects of repeatedly stopping and starting the profiler, as required when physically marking the roadway for corrective action. For grinding to be successful, correctly identifying on the pavement surface areas of defined localized roughness, requires a similar standard of care as collecting initial smoothness data. Incorrectly locating roughness features will not correct localized roughness. DETECTING AND MARKING LOCALIZED ROUGHNESS LOCATIONS IN THE FIELD In this section, a procedure to be followed in the field to accurately collect data and mark locations for grinding localized roughness is presented. This procedure requires the following: (a) Semi-permanent distance calibration track at the project (b) Semi-permanent markers (target cones) at regular intervals for each lane profiled (c) Precise data collection techniques (d) Localized roughness report from Owner-Agency (e) ProVAL SAM grinding strategy report (f) Computer with ProVAL SAM operating and displaying roadway section being marked for corrective action (g) Project Engineer to use only the smoothness data for defining areas of localized roughness (a) Semi-permanent Distance Calibration Track at the Project A distance calibration track, on-site or close to the project, in an area that will be accessible anytime, and that can accommodate the project s maximum profiling speed should be maintained for the duration of the project. The distance calibration track is used by the inertial profiler operator to assure the profiler s DMI is operating correctly. It is good practice (mandatory in some states) to calibrate the DMI each day, and at each speed, that the profiler will be operating. When using the profiler for marking grinding limits, the DMI is used to measure the distance from a known point (target cone) to a location of an area of defined localized roughness. Proper DMI calibration is critical. When utilizing the profiler in a start and stop fashion, as is required when marking locations for grinding, the DMI should be calibrated on the distance calibration track at the slowest constant speed possible. Also, the profiler operator must be aware of the capability of the specific DMI system in use on the inertial profiler vehicle, as some DMI device models may not operate correctly in a stop and start manner.

14 Higgins (b) Semi-permanent Markers (Target Cones) at Regular Intervals for Each Lane Profiled During the profile data collection, semi-permanent markers must be placed at pre-defined locations, such that these locations will appear in the profile data. Semi-permanent markers can consist of target cones. The photo detector will detect a special tape which is applied to a standard road cone. The base of the road cone is outlined, with paint, on the roadway surface to indicate the location to the operator should the cone be displaced. When the photo detector detects this marking, the location is recorded in the profile data. These locations marked both on the profile data and on the roadway are very useful later to accurately locate localized roughness locations in the field. Each lane profiled should at a minimum have target cones located at the start and stop of profiling data collection. Other important locations such as bridge decks, joints, etc., may also have similar markers depending on the project details. The smoothness specification indicates these locations must be identified in the profiler data, and using target cones during profiling will ensure these locations are marked on the profile data. After profile data has been collected and analyzed, and with known locations identified both on the profiler data and on the pavement surface, the operator can utilize these locations to aid in accuracy when locating areas of localized roughness. A regular interval of known locations in the collected profile data corresponding to known locations on the pavement surface allows small segments of the total lane length to be isolated. The ability to isolate data with fixed reference points when problems arise locating the specific roughness feature on the roadway, can greatly increase the likeliness of successful identification of the roughness location. (c) Precise Data Collection Techniques High quality data is essential. The operator should follow all specifications and manufacturer recommendations. High quality data is both accurate and repeatable. (d) Localized Report from Owner-Agency Typically, the Owner-Agency will produce a report of localized roughness. This report defines areas where the ride quality exceeds the specified threshold for localized roughness. While this report defines the areas of the roadway in need of corrective action, this report does not detail where grinding must occur to remove the area of localized roughness. A grinding strategy must be completed on the profile data for the specific grinding locations. (e) ProVAL SAM Grinding Strategy Report A grinding strategy will need to be properly formulated using the ProVAL SAM module. This formulated report will define where to start and stop diamond grinding to remove roughness features as identified by the Owner-Agency. After formulating the ProVAL SAM grinding strategy, each grind location will need to be located on the pavement surface for grinding. Physically marking each location of defined localized roughness requires the profiler vehicle to repeatedly start and stop. This repeated starting and stopping may cause the DMI to drift from the actual location as shown on the initial smoothness data. Depending on the field conditions, the drift can be measurably positive or negative. Typically, with a greater number of starts and stops, the operator should expect a greater distance drift. This presents a challenge when locating and marking localized roughness on roadways that have abundant roughness features and/or are significantly long projects. Within the ProVAL software, the profiles can be sectioned and each section can be isolated. Using a single section in ProVAL, in conjunction with the semi-permanent markings

15 Higgins (target cones) that were placed on the initial smoothness data prior to collection, the operator is equipped with a procedure to successfully remove DMI drift and greatly improve the success rate and accuracy locating areas of localized roughness. (f) Computer with ProVAL SAM Operating and Displaying Roadway Section Being Marked for Corrective Action Most localized roughness features are subtle disturbances in the roadway surface. The feature causing the ride quality to exceed a set threshold does not have to be the largest bump in the area. To aid in confidence that the operator has arrived at the correct roughness feature for grinding, the filtered profile trace with the simulated grind strategy can be displayed in the vehicle during the marking operation. This allows the operator to view the entire event, including the specific sequence of subtle roadway disturbances causing the roughness. The specific undulation pattern as seen on the filtered profile trace at an area of roughness is visible on the roadway surface. It is this visible pattern that the experienced operator can use as confirmation that the roadway area matches the ProVAL simulation area. (g) Project Engineer to Use Only the Smoothness Data for Defining Areas of Localized Inertial profiler smoothness data must be the sole determination for localized roughness designation. Basing localized roughness determination on the project engineer s interpretation of a smooth ride is not a successful method. CONCLUSION In conclusion, addressing and correcting defined localized roughness at the project level appears inconsistent with the present specification in Colorado. Colorado uses a minimum length to a localized roughness event, which is different from AASHTO R which has no minimum length for a localized roughness event. Incorporation of this procedure has resulted in many localized roughness locations that have an HRI between in/mi and in/mi that would have been detected by the AASHTO R procedure but not detected by the CDOT procedure. However, the effect of this change in the CDOT procedure does not seem to have affected detection of localized roughness locations having an HRI less than in/mi as the number of localized roughness locations detected for both CDOT and AASHTO R procedures were similar. The analysis of project level data collected by Earth Engineering Consultants, LLC displays successful correction of localized roughness as defined by AASHTO R specification. It appears successful correction of localized roughness is strongly linked to: Collecting accurate profile data Analyzing the data for localized roughness locations using ProVAL SAM Anchor points allowing isolation of individual sections within the project A method to successfully mark the localized roughness limits on the pavement Applying a systematic approach from the initial inertial profiler data collection process through the actual identification of roughness features, for diamond grinding provides project level results of corrective action which closely matches the ProVAL SAM software prediction and increases compliance to the project specifications. This procedure requires no additional

16 Higgins equipment other than that which is presently utilized on typical paving project sites. This paper provides an efficient and accurate procedure for profiler operators and project engineers to successfully locate and correct all areas of defined localized roughness as the computer generated ProVAL SAM grinding strategy suggests.

17 Higgins 0 REFERENCES. American Association of State Highway Transportation Officials. Standard Practice for Accepting Pavement Ride Quality When Measured Using Inertial Profiling Systems. Washington, DC, (00).. Swan, M., and S.M. Karamihas. Use of a Ride Quality Index for Construction Quality Control and Acceptance Specifications. In Transportation Research Record: Journal of the Transportation Research Board, No., Transportation Research Board of the National Academies, Washington, D.C., pp. 0.. ProVAL: Profile Viewing and Analysis Software, an US FHWA product, available from State of Colorado, Department of Transportation. 0. Specification 0.0 Conformity to Roadway Smoothness Criteria of HMA. Standard Specifications for Road and Bridge Construction.. Sayers, M.W. and Karamihas, S.M.. The Little Book of Profiling. The Regent of the University of Michigan.