The main objective of this research is to evaluate the risk related to geometric
design features for horizontal curves using reliability analysis. In this approach, Variables in
the design equations are treated as random variables. Appropriate design of geometric
elements in roads is an important feature for safety measures. The stopping sight distance
(SSD) and the radius (R) of the horizontal curve are the most important geometric elements at
the horizontal curve section. Therefore, the objective of this research is to check the
probability of noncompliance of a given horizontal curve taking into consideration the
random distribution of the various elements of a horizontal curve. Both SSD and R increase
with the increase in speed. However, the available sight distance (ASD) at site can be
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regulated by varying R and middle ordinate (M) at the curve section. This study focuses on
the intercity rural freeways roads in Egypt. Traffic and geometry data were collected for 9
curves from 3 freeway roads. All roads have posted speed limit of 100 to 120 km/h,
Horizontal curves were selected to cover the different geometric characteristics like (middle
ordinate, radius, super elevation, deflection angle, lane width and shoulder width) and traffic
data like Spot speeds. Reliability analysis using Minitab program focuses on two modes of
noncompliance in horizontal curve design. |
