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The maximum value of limiting gradient recommended by IRC in plain and rolling terrain is
30%
5%
70%
8%
5%
According to the Indian Roads Congress (IRC:73-1980), the limiting gradient for plain and rolling terrain is recommended as 1 in 20, which is equivalent to 5%. Limiting gradients are steeper than ruling gradients and are used only when the ruling gradient is impossible to achieve due to significant cost or topographic constraints.
According to the Indian Roads Congress (IRC:73-1980), the limiting gradient for plain and rolling terrain is recommended as 1 in 20, which is equivalent to 5%. Limiting gradients are steeper than ruling gradients and are used only when the ruling gradient is impossible to achieve due to significant cost or topographic constraints.
Gradient(%)=RunRiseтАЛ├Ч100
The design of a road profile relies on a hierarchy of gradients: ruling, limiting, and exceptional. The ruling gradient is the design goal for cost-effectiveness and vehicle performance. When site-specific conditions prohibit the use of the ruling gradient, the limiting gradient is permitted, allowing for increased vertical slopes at the expense of higher fuel consumption and slower vehicle speeds, especially for heavy goods vehicles.
Ruling gradient for plain/rolling terrain is 3.3% (1 in 30).
Limiting gradient is 5% (1 in 20).
Exceptional gradient is 6.7% (1 in 15).
Gradients are classified by IRC to optimize vehicle operation and construction economy.
Reduces total earthwork volume in hilly or restricted areas.
Prevents excessive road length when elevation change is rapid.
Increased fuel consumption for heavy vehicles.
Higher risk of traffic congestion due to slow-moving uphill vehicles.
Mountainous or restricted approach roads.
Situations where construction cost of standard gradients is prohibitive.
The IRC:73 code provides guidelines for geometric design of rural highways.
Option C (6.7%) corresponds to the 'Exceptional Gradient', which is permitted only for short stretches.
B is correct тАФ The IRC recommends 5% (1 in 20) as the maximum limiting gradient for roads in plain and rolling terrain.
Always remember the order: Ruling (3.3%) < Limiting (5%) < Exceptional (6.7%). These values are specific to plain/rolling terrain.