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: 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: Achieving consistent geometric design is an important goal in highway design to ensure obtaining safe, economical, and smooth traffic operation. Existing operating speed models for design consistency in North America and ...

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 ...

Abstract: This paper develops a system of disaggregate models that accounts for the effect of intersection, driver, and traffic characteristics on gap acceptance for left-turn maneuvers at urban T-intersections controlled by stop ...

Abstract: Achieving highway geometric design consistency is an important issue in the design and evaluation of rural highways to attain smooth and safe traffic operation. This paper presents a comprehensive literature review of ...