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The Length of Valley Curve calculation determines the appropriate length for a valley transition curve in road design, ensuring safe vehicle movement through vertical curves by considering headlight height and beam angle requirements.
The calculator uses the formula:
Where:
Explanation: This formula calculates the minimum length required for a valley curve to ensure adequate sight distance for safe stopping, considering the vehicle's headlight height and beam angle.
Details: Proper valley curve length is crucial for road safety, preventing accidents by ensuring drivers have sufficient visibility to stop safely when approaching a valley curve, especially during nighttime conditions.
Tips: Enter the deviation angle in radians and stopping sight distance in meters. Both values must be positive numbers for accurate calculation.
Q1: Why is headlight height and beam angle important in valley curve design?
A: Headlight height and beam angle determine the visibility distance at night, which is critical for safe vehicle operation through valley curves.
Q2: What factors affect the stopping sight distance?
A: Stopping sight distance depends on vehicle speed, driver reaction time, road gradient, and friction between tires and road surface.
Q3: How is deviation angle determined in road design?
A: Deviation angle is calculated as the algebraic difference between the grades of the two intersecting tangents in a vertical curve.
Q4: Are there minimum and maximum limits for valley curve length?
A: Yes, valley curves must meet minimum length requirements based on design speed and sight distance criteria, while maximum lengths are constrained by practical construction considerations.
Q5: How does this calculation differ for sag curves vs crest curves?
A: Valley curves (sag curves) primarily consider headlight sight distance, while crest curves focus on daylight sight distance over the curve.