Abstract
Sometimes when connecting a crest vertical curve, followed by a sag and another crest, a road disappears from the view of a driver to reappear later. Then, there is a loss of path or a hidden dip in a road. It is essential to avoid losses when they hide dangerous points, such as intersections or unexpected changes in direction. In addition, this loss disrupts drivers and its effect depends on quantitative relationships between the variables involved in the problem. This paper presents a quantitative procedure for studying hidden dips in roads. The method is based on calculating the sections visible and hidden by a driver using a Geographic Information System. An application to a Spanish road is presented. Procedure results were compared with in situ carried out studies and with a video of the highway recorded using a Global Positioning System equipped video camera embarked in a vehicle. The main quantitative issues related to hidden dips are discussed.
Highlights
Some combinations of horizontal and vertical alignments produce shortcomings in three-dimensional (3D) perspective
This paper presents a quantitative procedure for studying hidden dips in existing roads
A hidden dip length larger than 25 m or a length of hidden section larger than 75 m, criterion established by Zimmermann (2001), were required
Summary
Some combinations of horizontal and vertical alignments produce shortcomings in three-dimensional (3D) perspective. Among the safety-related, the partial disappearance of a road from the driver’s view with reappearance in the extension of the just-passed roadway section (called “hidden dip”) stand out. It is essential to avoid losses when they hide dangerous points, such as intersections or unexpected changes in direction (Fig. 1). This loss produces driver disorientation if visible sections are nearby and visual indicators suggest that hidden section alignment is similar to visible sections alignment. Sometimes, this disorientation causes erroneous decisions, which possibly cause an accident. If a driver believes that he sees all possible vehicles circulating towards him, this is not the case because there are some unnoticed vehicles in the hidden section
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