No abstract

The Mechanistic–Empirical Pavement Design Guide (MEPDG) represents a major improvement on its predecessors, particularly in its comprehensive coverage of environmental impact on pavement performance. Another improvement is the approach introduced to assess and accumulate damage created by traffic. A major strength of the MEPDG is the consideration given to the interaction between environmental, material, and traffic parameters, rather than consideration of only the parameters themselves. The process through which these interactions are considered sounds very comprehensive; however, is it practical? The Enhanced Integrated Climatic Model (EICM) is a core component of the MEPDG; it controls the material properties used in the analysis to a great extent. As a result, EICM predictions have a significant impact on MEPDG-accumulated damage and therefore on predicted service life. In a previous study, an effort was made to validate EICM predictions with field-measured temperature and moisture profiles outside the MEPDG. However, this effort was not successful. Therefore, the potential impacts of the accuracy of EICM predictions on MEPDG-predicted damage and hence on expected pavement service life were investigated. Eight weather stations closest to New Jersey's Long-Term Pavement Performance Specific Pavement Study 5 site were analyzed. In addition, to address the interaction between environment and traffic in the MEPDG, analyses were run with two traffic input levels: first with Level 3 traffic data and then with Level 1 traffic data.

Drainage characteristics have a significant effect on pavement performance. Pavements with poor subsurface drainage properties prematurely exhibit distress and have higher life-cycle cost. Shorter service life and higher maintenance cost are some of the reasons for the higher lifecycle cost. It has been proved in the last 20 years that subsurface drainage increases the pavement service life and reduces its life-cycle cost. A case study demonstrates and quantifies the benefits of providing subsurface drainage through reduction of moisture in daylighted base layers of flexible pavements. The effect of higher base course moisture content on the pavement in situ structural capacity was assessed through the analysis of deflection tests performed with the falling weight deflectometer. In this analysis, a structural adequacy index was used to assess the pavement structural service life. This information was then fed into a life-cycle analysis module to determine the effect of the higher moisture content on the pavement life-cycle cost. An increase in base course moisture content from 16% to 45% resulted in the reduction of pavement service life from 13 to 7 years. For a 40-year period, this translates to a three-fold increase in life-cycle cost for a 250-ft-long pavement section. Reducing moisture retention through various means, thereby improving the subsurface drainage quality of flexible pavement systems, can achieve substantial long-term savings.

No abstract

In this paper, the work operations in an actual small-to-medium sized design office have been analyzed for the purpose of optimizing the use of resources and improving work productivity. Using simulation, a model of the office operations was developed, incorporating all design steps and their employed resources. Several simulation experiments were then conducted to determine the optimum number of resources with balanced workloads and to optimize the teamwork strategy on projects. Details of the model and the simulation experiments are described and the advantages of the model to the management of engineering organizations are discussed.