The seasonal variation of the asphalt concrete (AC) modulus with changes in pavement temperature is discussed. The main goals of the research was to develop (a) regression models that enable design engineers to assess seasonal changes in AC modulus and (b) an algorithm for calculating a seasonal adjustment factor (SAF) that allows estimating AC modulus in any season from a known reference value. The study is based on analyzing data collected at Long-Term Pavement Performance (LTPP) program sites in both freezing and nonfreezing zones. The data were obtained from the LTPP database in the DataPave 3.0 software. The approach adopted in this study was to select LTPP-seasonal monitoring program sites that represent various climatic regions and use the backcalculated modulus and pavement temperature data to develop regression models for the modulus-temperature relationships for various sites in both freezing and nonfreezing zones. Two regression models were developed to relate the variation in modulus with the variation in pavement temperatures in various seasons for both freezing and non-freezing zones. These models incorporate AC layer properties such as thickness, bulk specific gravity, air voids, and asphalt binder grade. A model for determining the SAF was also developed.

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The transportation planning process is considered a point of interest in the field of urban sustainable development. After many years of development and knowledge, it was found that transportation modelling has a fundamental role in transportation planning. There are many types of transportation models that represent the travel behavior in the study area. The traditional travel demand model is one of the most widely used in transportation planning modelling. Mainly there are four stages in the traditional travel demand model. These stages are trip generation, trip distribution, mode choice, and trip assignment. The trip assignment model is the result for the previous three stages and could estimate the traffic flow on network links. This paper represents the traditional travel demand model so-called "four-step model" and its structure as well as the validation methods for the trip assignment model. The overview also includes the applications of the traffic assignment model, considering it the final stage of the travel demand model, in the sustainable development of urban cities.