Ground‐water modeling is hindered, in general, by the lack of adequate information about the ground‐water system and hence the need for an interactive and efficient system for data preparation and results analysis. Such a lack of information usually necessitates the use of a tedious iterative methodology within a sensitivity analysis scheme. This study facilitates modeling efforts by using the data‐handling and graphical capabilities of a geographic information system in site‐specific, numerical modeling of ground‐water resources. Data for the island of Oahu, Hawaii, are given to illustrate the approach. The modeling procedure is integrated within the GIS as an item in the main menu. A USGS model, known as MOC, is linked into the system and applied to a case study to illustrate the procedure. The linkage is generic in nature and can be extended to other models as well. The availability of a programming language in the GIS package facilitates pre‐ and post‐processing efforts within custom‐made dialogue boxes and pull‐down menus. On‐line help screens for modeling as well as data handling can also be designed.

To achieve effective pavement maintenance, the life expectancy and timing of treatment applications need to be determined. The Long Term Pavement Performance (LTPP) program includes the Specific Pavement Study-3 (SPS-3), which focuses on this subject. The treatments applied are chip seals, crack seals, slurry seals, and thin overlays. In studying the life expectancy it is not feasible to wait for all the sections in the experiment to fail. Thus, there is a need to determine the life expectancy while making efficient use of the available data collection funds. Survival data analysis is a statistical technique that meets this need by accounting for the portion of the sections in which the exact time the treatment lasted is not known. The application of this technique to flexible-pavement maintenance is presented. In addition, some results of the LTPP SPS-3 experiment are presented to the highway community. The focus is on the LTPP Southern Region. The results showed that the probability of failure was two to four times higher for the sections that were in poor condition at the time the treatment was applied than those sections that were in better condition. The median survival times for thin overlays, slurry seals, and crack seals were 7, 5.5, and 5 years, respectively. The chip-seal sections had not yet reached the 50 percent failure probability after 8 years of the SPS-3 experiment. Accordingly, chip seals appear to have outperformed the other treatments investigated in this study in delaying the reappearance of distress.

The results of a study conducted to determine the relationship between changes in the surface distress of flexible pavements and incremental changes in the international roughness index (IRI) or ride quality by using Long-Term Pavement Performance (LTPP) program data are presented. The results of the regression analyses completed to identify those distresses found to be important and related to incremental changes in the IRI were obtained under the sponsorship of NCHRP Project 1-37A (Development of the 2002 Guide for the Design of New and Rehabilitated Pavement Structures). The results from the study have shown that selected distresses do have a significant effect on incremental changes in IRI with time and traffic. The results summarized can be used for the management, design, or evaluation of pavement structures.

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