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Use of PMS Data for Performance Monitoring with Superpave as an Example
5. DOT Reporting Techniques on Materials and Construction, Actual Versus Ideal
5.1. Actual Situation
Current DOT practice is normally to plan, design, bid, and build projects. Included in these functions are the materials requirements and the QC/QA project acceptance requirements. Each function is treated as a separate entity, i.e., the design plans and specifications govern the project in a general fashion. Intermediate laboratory tests to develop project mix parameters are the "property" of the materials group, tied to the assigned project number. In a like manner, the day-to-day materials tests and QC/QA testing performed by construction inspectors are delegated to the project file, in the materials area and project office, or sometimes by the contractor. Usually duplicate materials testing data are provided to the project inspectors for payment and audit purposes. In most cases, data on materials, mix design, and construction details are recorded on paper, so this information is stored in flat files by different groups and is often difficult to access after the project is completed.
The pavement design plan for a particular rehabilitation project can normally be found in an inter-department communication, or memorandum, from the pavement design engineer to the Manager of Preliminary Engineering Studies Section, the project engineer or coordinator, or the design engineer. Such a memorandum is routinely copied to the materials engineer. In some cases, further correspondence follows between these parties with various revisions until a final design recommendation is made. In most cases this will be accompanied by one or more drawings with the cross-sections of the pavements in question. Apart from the design for the main pavement section, design details can be given for shoulders, ramps, overpasses, and temporary crossovers. This correspondence normally refers to the name of the road and the mile posts of the section, to a design number, and to a contract number. Often a project number is used also. Copies of these memoranda are filed at various different locations within a DOT. The time lapse between the first design memorandum and the final version can be from one to several years, since there can be long delays for a project between preliminary design and final construction.
Data on the laboratory mix design are developed by the materials group, they are tied to a design number and a project number. Most of the historic laboratory data are stored in flat files, and consequently are difficult to access. Currently there is a trend to make such data available in electronic format, either with the help of a commercial system such as LIM (Laboratory Information Management), or through custom made spreadsheets on a PC. In that way it is easier to analyze and to share the data, but the fact that such data are often still residing on a PC or a dedicated server makes it difficult for other interested parties in the DOT to access such data.
The routine testing data and the quality control and assurance data can come from several sources. There is a trend of increased testing by contractors or specialized consultants, although quality assurance is mostly still carried out by DOTs. Such data were usually made available in paper files until recently, when attempts were made to streamline data storage and transfer by using electronic systems. AASHTO introduced two programs for this purpose, Site Manager and BAMS (Bid Analysis and Monitoring System), but both have the limitation that they can not be integrated easily with other databases, such as PMS. Site Manager also has the drawback that it does not have any sort of filter or query capabilities.
Knowledge of and easy access to materials and construction data is essential if the long term performance of pavements is to be analyzed for constructive purposes. Such data should be linked by the uniform identifiers of date, project number, route and cumulative mileage to any follow-up performance data obtained after construction is completed. Routine measurements as well as specialized tests such as FWD should be tied together also by route and milepost to create a more complete picture of historical performance and expected performance trends by various classes of pavement. In this respect it should be stressed that records should be kept of all required data. Some DOTs do not measure as-laid thickness routinely, but this information is essential for analysis.
Arizona DOT has for several years maintained a separate electronic database for projects, which is called Projmod. This file contains the following information: Route, lane, direction, mileposts (begin and end), material category applied and its thickness (as designed, for up to six layers), project name, and date. The file does not give actual thickness and material properties (designed or actual), but it is a good start for any engineering analysis.
5.2. Ideal Situation
In the ideal situation all relevant materials, construction and performance data would be available in electronic format and a full integration and sharing of such data, as described in Section 3.5, could be realized. There would be major advantages if all required data are indeed entered electronically:
- Data entry would only have to be done once,
- Less room for mistakes,
- Available immediately,
- Corrective actions are possible in a timely manner,
- Automation possible (link to GPS during construction, field testing, etc)
The web-based system developed by the University of Washington in cooperation with Washington State DOT offers an excellent methodology for both data warehousing, inspection, linking and analysis. Details of this system and examples of its capabilities are given in Appendix F.
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