1. What is Psychological Widening at Horizontal Curves?

Definition: Psychological widening refers to the extra space provided on horizontal curves to account for driver perception and comfort.

Purpose: It helps ensure safe vehicle operation on curves by compensating for the natural tendency of drivers to maintain greater clearance on curved sections.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( W_{ps} \) — Psychological widening (meters)
• \( V \) — Vehicle velocity (meters/second)
• \( R_{mean} \) — Mean radius of the horizontal curve (meters)

Explanation: The formula calculates the additional width needed based on vehicle speed and curve radius, with a tolerance factor of ±5% by default.

3. Importance of Psychological Widening

Details: Proper widening improves safety, reduces driver stress, and accounts for vehicle dynamics on curves. It's especially important for high-speed roads.

4. Using the Calculator

Tips: Enter the vehicle velocity in m/s, mean curve radius in meters, and tolerance percentage (default 5%). All values must be > 0 (except tolerance which can be 0).

5. Frequently Asked Questions (FAQ)

Q1: Why is psychological widening needed?
A: Drivers naturally take wider paths on curves for comfort and safety, so extra width prevents encroachment into adjacent lanes.

Q2: How does velocity affect widening?
A: Higher speeds require more widening as drivers' perception of the curve changes and vehicles need more maneuvering space.

Q3: What's a typical tolerance percentage?
A: ±5% is common, but this can vary based on road classification and design standards.

Q4: How does curve radius affect the calculation?
A: Tighter curves (smaller radius) require more widening than gentle curves.

Q5: Is this the same as mechanical widening?
A: No, psychological widening is in addition to any mechanical widening needed for vehicle dynamics.

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