Length of Valley Curve given Beam Angle and Height of Head Light Calculator

Valley Curve Length Formula:

\[ LV_c = 2 \times SSD - \left( \frac{1.5 + 0.035 \times SSD}{N} \right) \]

Length of Valley Curve (LV_c): meters

1. What is Length of Valley Curve?

Definition: The length of valley curve is the transition curve made fully transitional by providing two similar transition curves of equal length.

Purpose: It ensures safe vehicle movement through vertical curves by providing adequate sight distance.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ LV_c = 2 \times SSD - \left( \frac{1.5 + 0.035 \times SSD}{N} \right) \]

Where:

\( LV_c \) — Length of valley curve (meters)
\( SSD \) — Stopping sight distance (meters)
\( N \) — Deviation angle (%)

Explanation: The formula calculates the minimum length required for a valley curve based on stopping sight distance and the deviation angle between grades.

3. Importance of Valley Curve Calculation

Details: Proper valley curve length ensures driver comfort, vehicle safety, and adequate headlight visibility at night.

4. Using the Calculator

Tips: Enter the stopping sight distance in meters and deviation angle in percentage (default 0.08%). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What is stopping sight distance?
A: The distance required for a driver to see an obstacle and safely stop before reaching it.

Q2: What's a typical deviation angle?
A: Common values range from 0.05% to 0.20%, with 0.08% being a typical default value.

Q3: How does headlight height affect the calculation?
A: The formula incorporates standard headlight height (0.6m) and beam angle (1°) through the constants.

Q4: When would I need a longer valley curve?
A: For higher design speeds, steeper grade changes, or when additional safety factors are required.

Q5: Does this include safety factors?
A: The formula provides minimum requirements. Engineers often add safety margins based on specific project needs.