Psychological Widening on Horizontal Curves Calculator

Psychological Widening Formula:

\[ W_{ps} = \frac{v}{9.5 \times \sqrt{R_t}} \]

Psychological Widening (m):

With Tolerance (±5%):

1. What is Psychological Widening on Horizontal Curves?

Definition: Psychological widening is the extra width of pavement provided for psychological reasons such as overhangs of vehicles and greater clearance for crossing.

Purpose: It accounts for driver comfort and perception when navigating horizontal curves at different speeds.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ W_{ps} = \frac{v}{9.5 \times \sqrt{R_t}} \]

Where:

\( W_{ps} \) — Psychological widening (meters)
\( v \) — Speed of vehicle (km/h)
\( R_t \) — Radius of curve (meters)

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

3. Importance of Psychological Widening

Details: Proper widening improves driver comfort, reduces perceived risk, and enhances safety on curved road sections.

4. Using the Calculator

Tips: Enter the vehicle speed in km/h, curve radius in meters, and tolerance percentage (default 5%). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: Why is psychological widening important?
A: It accounts for driver perception and comfort, making curves feel safer and more navigable.

Q2: How does speed affect the widening requirement?
A: Higher speeds require greater psychological widening as drivers perceive curves as more challenging at speed.

Q3: What's a typical tolerance percentage?
A: ±5% is common, but this can be adjusted based on specific project requirements.

Q4: How does curve radius affect the result?
A: Tighter curves (smaller radius) require more psychological 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 operation.