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If Cross Slope of a country is up to 10 to 25% the terrain is classified as
Plain
Rolling
Mountainous
Steep
Rolling
In highway geometric design, the IRC (Indian Roads Congress) classifies terrain based on the cross slope of the country. A cross slope ranging from 10% to 25% is classified as 'Rolling' terrain.
In highway geometric design, the IRC (Indian Roads Congress) classifies terrain based on the cross slope of the country. A cross slope ranging from 10% to 25% is classified as 'Rolling' terrain.
S=HVтАЛ├Ч100 тАФ Calculation of cross slope percentage S where V is vertical rise and H is horizontal distance.
The terrain classification is determined by the natural ground slope perpendicular to the road alignment. As the percentage of cross slope increases, the difficulty of construction, earthwork, and requirements for horizontal/vertical curves change. Rolling terrain presents moderate gradients compared to flat ground, necessitating specialized design considerations for sight distance and vehicle speeds.
Plain terrain: Cross slope up to 10%.
Rolling terrain: Cross slope 10% to 25%.
Mountainous terrain: Cross slope 25% to 60%.
Steep terrain: Cross slope greater than 60%.
Ensures uniform geometric design standards.
Optimization of earthwork costs during road planning.
Classification depends on average slope, which may vary significantly within a single project corridor.
Highway alignment selection.
Estimation of road construction costs.
Determination of permissible gradients and design speeds.
The classification is crucial for determining the 'Ruling Gradient' and 'Limiting Gradient' on roads.
Rolling terrain often requires more frequent curvature than Plain terrain but less than Mountainous terrain.
B is correct тАФ A cross slope of 10% to 25% is officially designated as Rolling terrain according to Indian road standards.
Remember the 10тИТ25-60 rule: 10% (Plain), 10тБ╗┬▓тБ╡% (Rolling), 25-60% (Mountainous), >60% (Steep).