Abstract: The effect of combining horizontal and vertical curves on operational conditions has been the subject of research over the last few years. A number of studies have reported that combining horizontal curves with crest and ...

Abstract: The geometric features of a highway network play a significant role considering the fact that collisions occur disproportionately on horizontal curves. Based on extensive literature review, the problem mainly stems from ...

Abstract: Highway designers occasionally use unsymmetrical vertical curves in locations where the vertical clearance controls. In this case, the symmetrical curve, which has a constant rate of change of grade, is replaced with two ...

Abstract: The American Association of State Highway and Transportation Officials (AASHTO) presents general controls for the combination of horizontal and vertical alignments. Excellence in alignment coordination enhances safety, ...

Abstract: The perception of the driver of the road features ahead is an important human factor that can considerably affect traffic safety and design consistency, and should be addressed in road design. An erroneous perception of ...

Abstract: Headlight sight distance has been an important element in designing sag vertical curves because nighttime drivers need sufficient sight distance for stopping, and also because they depend on the road marking to maintain ...

Abstract: Poor coordination of horizontal and vertical alignments can create locations where the available sight distance drops below the required sight distance. Therefore, current design guides have recommended a number of guidelines ...

Abstract: The concept of design consistency has lately been gaining greater acceptance in North America. Considerable research work is being carried out and steps have already been taken to incorporate this concept into the design ...

Abstract: Current design practices in North America are based mainly on 2D analysis of the highway alignment and do not account for the operating speed adopted by drivers. A more accurate approach should consider the interaction ...

Abstract: According to current highway design standards, horizontal and vertical alignments are treated separately in two-dimensional (2D) projections. In this paper, a model developed by the writers is used to study the effects of ...