Total Widening Needed at Horizontal Curve Calculator

Widening Formula:

\[ W_e = \frac{n \times l_{fr}^2}{2 \times R_{mean}} + \frac{v}{2.64 \times \sqrt{R_{mean}}} \]

Number of Lanes:

Distance between Front and Rear Wheel:

Mean Radius of Curve:

Velocity:

m/s

Tolerance:

Total Widening Needed (m):

With Tolerance (±5%):

1. What is Total Widening Needed at Horizontal Curve?

Definition: This calculator determines the additional width required on horizontal curves to account for vehicle maneuvering and driver comfort.

Purpose: It helps road designers ensure safe vehicle operation on curved sections by calculating both mechanical and psychological widening needs.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ W_e = \frac{n \times l_{fr}^2}{2 \times R_{mean}} + \frac{v}{2.64 \times \sqrt{R_{mean}}} \]

Where:

\( W_e \) — Total widening needed (meters)
\( n \) — Number of lanes
\( l_{fr} \) — Distance between front and rear wheels (meters)
\( R_{mean} \) — Mean radius of curve (meters)
\( v \) — Vehicle velocity (meters/second)

Explanation: The first term calculates mechanical widening for vehicle maneuvering, while the second term accounts for psychological widening for driver comfort.

3. Importance of Widening Calculation

Details: Proper widening ensures safe vehicle operation, reduces accident risk, and improves driver comfort on curved road sections.

4. Using the Calculator

Tips: Enter the number of lanes, wheelbase distance, curve radius, vehicle speed, and tolerance percentage. All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What is the typical wheelbase distance?
A: Standard passenger vehicles have about 2.5-3m wheelbase, while trucks may have 5-7m. The default 9m represents large vehicles.

Q2: Why include a tolerance percentage?
A: The ±5% tolerance accounts for variations in vehicle types, driver behavior, and road conditions.

Q3: How does curve radius affect widening?
A: Tighter curves (smaller radius) require significantly more widening than gentle curves.

Q4: What units should I use?
A: All inputs should be in meters and meters/second for consistent results.

Q5: When is psychological widening most important?
A: At higher speeds, psychological widening becomes more significant for driver comfort and safety.