Length of Curve given Change in Grade where S is more than L Calculator

Length of Curve Formula:

\[ L_c = 2 \times SSD - \left(\frac{800 \times h}{N}\right) \]

Length of Curve (m):

1. What is Length of Curve given Change in Grade where S is more than L?

Definition: This calculator determines the length of a vertical curve when the sight distance (SSD) is greater than the curve length (L) based on the height of vertical curves and the change in grade.

Purpose: It helps civil engineers and road designers ensure safe sight distances on vertical curves in road design.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ L_c = 2 \times SSD - \left(\frac{800 \times h}{N}\right) \]

Where:

\( L_c \) — Length of curve (meters)
\( SSD \) — Sight stopping distance (meters)
\( h \) — Height of vertical curves (meters)
\( N \) — Change in grade (percentage)

Explanation: The formula calculates the minimum curve length needed to provide adequate sight distance when the sight distance exceeds the curve length.

3. Importance of Curve Length Calculation

Details: Proper curve length calculation ensures driver safety by providing sufficient visibility to stop or maneuver when encountering changes in road grade.

4. Using the Calculator

Tips: Enter the sight distance (SSD) in meters, height of vertical curves in meters, and change in grade in percentage. All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What is sight distance (SSD)?
A: SSD is the minimum distance a driver needs to see to safely stop or maneuver their vehicle when encountering an obstacle.

Q2: What's a typical height for vertical curves?
A: The height typically ranges from 1.0m to 1.8m, representing driver eye height to object height.

Q3: How is change in grade determined?
A: It's the algebraic difference between the entering and exiting grades of the vertical curve (e.g., +3% to -2% would be 5% change).

Q4: When is this formula applicable?
A: This formula is used specifically when the sight distance (S) is greater than the curve length (L).

Q5: What units should be used?
A: All inputs should be in meters for distance and percentage for grade change.