What do you mean by extrawidening explains with types as mathematicaly also

Extra Widening of Roads (Highway Engineering)

Definition (1 mark)

Extra widening is the additional width provided to a road at curves over the normal width to allow safe and smooth movement of vehicles.

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Need / Purpose of Extra Widening (1–1.5 marks)

• To accommodate off-tracking of rear wheels.
• To provide psychological comfort to drivers on curves.
• To reduce chances of accidents and collisions.

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Types of Extra Widening (2–2.5 marks)

1. Mechanical Widening (Wₘ)

• Due to off-tracking of vehicle wheels while negotiating curves.
• Depends on wheelbase and radius of curve.

2. Psychological Widening (Wₚ)

• Provided for driver comfort and safety.
• Depends on speed of vehicle and curve radius.

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Mathematical Expression of Extra Widening (Important)

Total Extra Widening (Wₑ):

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Mechanical Widening: nl^2/2R

Where:

• N= number of lanes
• l= wheel base of vehicle
• R= radius of curve

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Psychological Widening: V/9.5sqrt R

Where:

• V= speed (km/hr)
• R= radius of curve (m)

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Conclusion (1 mark)

Extra widening is essential on curves to ensure safe vehicle movement, accounting for both mechanical factors (vehicle behavior) and psychological factors (driver comfort), thereby improving road safety and efficiency.