THREE-DIMENSIONAL ANALYSIS OF HIGHWAY CONSISTENCY AND ITS IMPACT ON HIGHWAY CAPACITY

Abstract

There are many phases that are incorporating in the design of highway systems including •transportation planning, highway geometric design, highway construction, and traffic operation. Among these phases, highway geometric design is the technical phase that foUows the stage of route selection, and it is the one that most related to traffic safety. A consistent highway geometric design is the design that resulted from complicated procedure in which the laws of motion as will as the vehicle and road user characteristics are incorporated to produce safe and efficient traffic operations and meets driver expectations. In order to ensure the safety and efficiency of highway systems, different design standards have been issued by different countries to fit their traffic characteristics and environmental conditions. However, these standards are mainly based on the two­ dimensional (2D) analysis of highway alignments where horizontal alignment, vertical alignment, and cross section are designed separately. Therefore, exact adherence to the design standards does not guarantee• obtaining a consistent design.