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Use of PMS Data for Performance Monitoring with Superpave as an Example
9. Phase 2 - Pathfinder Study in Maryland
The results of the study described in the previous sections were presented and discussed during a project review meeting with several FHWA representatives on February 21, 2001 in Washington DC. Notes of that meeting are given in Appendix E. A preliminary report "Use of PMS Data for Performance Monitoring with Superpave as an Example, Phase 1" was submitted to FHWA on May 30, 2001.
On August 21, 2001, TRDI received a Purchase Order to extend the study with the following statement of work:
On August 27 and 28, 2001, the Project Team met with representatives of Maryland SHA to discuss the following:
A report about this meeting can be found in Appendix G-1.
On October 29, 2001, members of the Project Team had a follow-up meeting with representatives of the Office of Materials and Technology of the State Highway Administration of Maryland (MDSHA) at their office in Maryland. The following points were discussed:
MDSHA prepared a list with proposed data fields, data availability and comments for QC/QA data, Mix design information, Pavement design information, and Pavement Management data, together with a suggested list of reports that should cover the effects of various parameters on rutting, reflective cracking, ride quality and cracking. The Project Team proposed to add a few data fields in the areas of existing pavement structure, mix temperatures during spreading and compaction, performance data of laboratory- and actual mixes, and date when pavement section is opened to traffic. More detailed Notes about this meeting are given in Appendix G-2.
The PMS does not yet contain data on maintenance, but it was agreed that the linking system should provide for the inclusion of maintenance activities in the future.
The recommended data fields are given in Table 2, and Table 3 lists the types of analysis and evaluation that would be desirable.
9.2.Collecting Data and Conversion to Electronic Format
In Maryland only the Superpave projects designed after June 1999 have sufficient data to make the performance analysis meaningful. MDSHA therefore selected 7 Superpave projects carried out since 1999, and made an effort to collect all available data listed in Table 2 from their QA/QC, Mix design, Pavement design and Pavement management records, and to import these data into an electronic database. Apart from the data that were not available (N/A in Table 2) they were unable to retrieve data on Aggregate Properties and on Binder Test Results. Other data, mostly those in paper files, were hard to retrieve. An overview of the sources of data and the difficulty to retrieve them, is given in Table 4. More details are given in Appendix G-4.6. For the seven Superpave projects it took 2 staff members about 4 weeks working full time to retrieve the data and to enter them into an electronic database. They used an Access database about 45 MB in size. Electronic data storage will in the future improve this process and speed it up considerably.
9.3.Setting up Database in modified UW Web-site System
As mentioned in Section 8.6. the University of Washington (UW), in cooperation with Washington State DOT and NCAT, recently developed a fully integrated website that contains relevant data of Superpave contracts, including performance data [White 02]. This new development was possible because nearly all essential data on materials and construction are available electronically. In addition a major effort has been made to link these data to performance measurements from WSDOT's Pavement Management System (PMS). The data is available on a website (see Appendix F) from which they can be easily organized, downloaded and analyzed.
In the initial phase of the study the Project Team considered the use of a modified version of the QC/QA module of the Superpave/AASHTOware data set [AASHTO 00] for collecting and storing the required Superpave data. After further review and knowledge of the University of Washington system, two reasons emerged to support why it proposed to use the web based system developed by UW for the Maryland Database with Superpave projects:
Dr. Joe Mahoney and Mr. George White of the Civil & Environmental Engineering Department of UW offered their help in making their web-site system available for the seven Superpave projects from MDSHA. In order to do this George White undertook the following:
The total effort of George White for the above mentioned activities was about one man-month. Most of this effort went into the last point, clarifying the meaning and inter-relationship of the data, getting additional data, adjusting units, converting systems, etc.
UW received most of the data from MDSHA during the first half of December, 2001. On December 18, 2001, two members of the Project Team visited UW to discuss the possibilities for a life demo of the capabilities of the UW web-site system using the Maryland data during the TRB 2002 Conference. (A visit report is given in Appendix G-3). It appeared that MDSHA had forwarded a substantial database with complete data for most of the fields. Still, for 10 fields no data were available at all, and for several other fields there were insufficient data. Consequently no analysis could be done for cracking or other distresses, for the effects of mix temperature, the influence of the use of a MTV, the influence of day or night paving, the effect of different roller patterns or roller types, or the effects of actual versus designed layer thickness. It appeared that data with exact locations of lots and sub-lots were also missing, but it was agreed for one section only to divide the lots evenly over that section so that, for demonstration purposes only, the correlation between a lot and its performance could be shown. Another limitation of the data for the seven Superpave projects is that there are only one or two years of performance data, so it is difficult to create meaningful plots of performance over time. Some of the older Superpave projects do have several years of performance (see Appendix D), but these projects have insufficient data on materials and construction.
9.4.Demonstration of Capabilities of Web-site System of UW
The final presentation of the current project took place on January 15, 2002 at the TRB Conference in Washington DC. The purpose of the meeting was to give the FHWA and representatives of industry, universities, committees and state DOTs an overview of the progress made and a demonstration of the web-based evaluation system developed by the University of Washington. Representatives of the FHWA, TRB, AASHTO, Maryland SHA, Washington State DOT, NAPA, Asphalt Institute, NCAT, Battelle and the Universities of Maryland and Washington attended the meeting.
After a welcome and introduction by Carl Monismith, Pim Visser gave an overview of the project and of the progress made so far. He described the concept of linking materials and construction data to performance and distress measurements; the possibilities in case of an ideal situation of having all required data available in electronic format, and the limitations of the current situation where many data are either not available or difficult to access. He reviewed phase 2 of the project: the Pathfinder Study carried out with data from Maryland SHA, with as two main elements the actual collection of data, and their incorporation into the web based system developed by the University of Washington (UW). See also Appendix G-4.
Pete Stephanos described the efforts of MDSHA to collect the agreed set of data. For each data category he described the source of the data, and the level of difficulty to retrieve them. See also Appendix G-4.
Joe Mahoney introduced the development and capabilities of the HMA electronic web-based database and evaluation system, used by the State Pavement Technology Consortium of Texas, Minnesota, California and Washington on an experimental basis.
George White presented a "live" demonstration of the web-based evaluation system developed by him in cooperation with WSDOT and NCAT at the University of Washington. He showed two websites: http://hotmix.ce.washington.edu/hma/ with the recent data from MD and http://hotmix.ce.washington.edu with data from WA, TX and MI. Since many data were still missing it was difficult to show well-defined plots, however most of the desired relationships were shown and the audience got a good idea of the capabilities of the system.
It was stressed that the demo should be judged on capabilities, rather than these interim results. Additional information about the websites, together with examples of web pages, is given in Appendix F.
The animated discussion after the meeting can be summarized as follows:
More details about this Special Meeting can be found in Appendix G-4.