Civil Engineering - Highway Engineering - Discussion

I think opt A is the actual incorrect statement. Because from the formulae E= e (rate of super elevation) * B (width of pavement) for designing super elevation, for a perticular pavement width B is same but rate of superelevation can be changed. So width is not proportional to value of superelevation (E). Again superelevation is provided for counteract centrifugal force which is ev^2/gR. So opt C is correct statement. So. Who answered opt A I will go with them.

Rate of super elevation e=E/B, & E=eB.
E = super elevated hight or superelevation.
But e = v^2/127R,
i.e E = v^2B/ 127R.

From this equation, we can conclude that super elevation (E) is directly proportional to the velocity of the vehicle, while the rate of superelevation (e) is inversely proportional to the width of the pavement (B).

Guys. Question is actually trick you. B is Right.
E=eB.
e=v*v/gR.

SO,
E=v*v*B/gR.

From the final equation.
E directly proportion to width, the square of the velocity and, inversely proportional to the g and R.

here, superelevation does not directly proportional to the velocity of vehicles, but the only square of the velocity.

SO, answer B IS RIGHT.

Option A will be the answer.

Because, super elevation (e) = tan(theta)= Tangent/Base.
So, if base ie. The width will increase then Tangent ie. The rise of the outer edge will be increased to maintain as tan (theta). After that theta (angle of inclination) will be the same.
So, e= tan theta dependable on theta and not dependable on the width

As super elevation e+f=v^2/ (g.r) so it is directly proportional to the design speed option b is incorrect because the speed of vehicles is mentioned there in the statement not the design speed of the vehicle will differ for the different vehicle so it is incorrect.

Because s.e can be made on design speed.

E = eB.
Here in above relation;
e= Rate of super elevation,
And E = total super elevation.

Therefore total super elevation is directly proportional to width B.
But rate of super-elevation that is e is not proportional to width as the product of e and B is equal to E.

So, option A is incorrect.

Basically super elevation is provided to counter the centrifugal force and to reduce the tendency of fast moving vehicles to overturn. If super elevation is less or zero vehicles will have to reduce their speeds to safely turn it. Hence answer B is correct.

e=v2/gR,

So answer A is correct because question is asking incorrect statement, but superelevation is directly proportional to the square of velocity and inversely proportional to acceleration due to gravity and radius of curvature.

Equation e + f = v2/127 R.

Thus e directly proportional to velocity and inversely proportional to radius of curvature which
is right.

So incorrect answer is option C inversely proportional to acceleration due to gravity.

Actually, incorrect answer is opt A because when the width is extra large we need not provide super elevation and when the width is narrow we should increase super elevation to provide safe passage of vehicles.