SIGHT DISTANCE RELATIONSHIP INVOLVING HORIZONTAL CURVES.

This research provides exact solutions for the case where the sight distance is greater than the curve length for a moving observer. It relates the available sight distance; horizontal curve geometric elements; and location of observer, and road object, and clearances to an obstacle to vision located inside the driving path of the observer. The lesser clearances required for these cases are often as much as 50 percent smaller than those obtained using the longer curve case. User-friendly design procedures and aids using these results have been developed and are presented. They are easily programmable, and can serve as a part in a decision support system.