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The aim of this study was to develop operating speed models for different vehicle classes for rural two-lane highways. Ten horizontal curves, connected with relatively long tangents, with various geometric characteristics, were selected to perfom this study. A series of traffic surveys were carried out using automatic traffic counters, to collect sufficient speed data for different vehicle classes. Preliminary analysis confimed the necessity of the classification of the vehicles in order to develop operating speed models. Further analysis looked at the differences between speeds on inside and outside lanes of curves and significant differences were found between the speeds of the two directions. Several operating speed models were developed for tangents and curves for different vehicle classes. These models are very useful and can be used for design consistency evaluations.

Although, roundabouts have proved significant in improving safety, capacity, and environmental performance, they have shown an increasing crash rate in Oman over the years. This paper aims to evaluate the safety performance of the roundabouts in Oman through the development of crash prediction models to examine the relationship between the geometric, traffic flow variables and crash frequency and severity. These models can determine which variables are the best indicators for safety performance.Generalized Linear Modelling (GLM) technique with Poisson or Negative Binomial Regression (NBR) was carried out to develop these models. Two types of models were developed separately; the flow-based models including only exposure functions, and the full models containing both exposure functions and other significant geometry and traffic variables. The result shows that the 85 th percentile speed, number of lanes at specific approach, entry angle, and circulating width were the most significant variables.It was found that reducing the 85 th percentile speed reduces the total and injuries crashes, however Downloaded by [Athabasca University] at 09:40 21 June 2016 ACCEPTED MANUSCRIPT ACCEPTED MANUSCRIPT 2 increasing the number of lanes in each approach and adding right-turn bypass lane may be the most effective methods to reduce the rear-end accidents.

The destination choice is an essential step of the travel demand modeling. Many previous studies were concentrated on land use which means that the utilization of land for different activities such as residential, commercial, industrial, educational, etc. is linked with travel demand. Accessibility is often seen to be an important determinant of the activities destination choice. This study is concerned with using the accessibility concept to investigate the utility function of the activity destination choice. A case study is Port Said (PS) City in Egypt. The characteristics of time, cost, and income level are obtained from activity based comprehensive transportation surveys. The benefit or utility of choosing a specific activity (BM values) are estimated based on the calculation of accessibility benefit from time-space geography measures for different zones in PS. Binary and Multinomial logit models were used for daily activities performed by individuals. During different time segment, the model predicts individual probability of choosing one of the following five activities: work, shopping, school, university, and Leisure. The accessibility benefits are examined associating with decreasing travel time (public transport-oriented development), improving income level for poor, and restricting car use. Finally, the model approved to be sensitive to different measures and hence it can be used as an effective informative tool to the decision makers.