Civil Engineering - Highway Engineering - Discussion

Discussion Forum : Highway Engineering - Section 1 (Q.No. 1)
1.
A district road with a bituminous pavement has a horizontal curve of 1000 m for a design speed of 75 km ph. The super-elevation is
1 in 40
1 in 50
1 in 60
1 in 70
none of these.
Answer: Option
Explanation:
No answer description is available. Let's discuss.
Discussion:
95 comments Page 6 of 10.

Yamir said:   8 years ago
F is not gives that doesn't mean we will not use 127 Maximum times we use 127 for already designed roads.

Harveer singh said:   8 years ago
1 in 40 is the right answer.

V^2/125r ( f is not given).

Rajesh kumar saini said:   8 years ago
1/40 is the right answer.

Sameer naik said:   8 years ago
Why used 75% in que not mention mixed traffic?

Babugouda said:   8 years ago
Here,

e = v2/gr when v is in m/s.
e = v2 /127r when v is in kmph.

Palash mondal said:   8 years ago
The actual formula of super elevation is;

We know the super elevation is calculated for 75% of design speed.

So,
E = (.75V)^2/GR.
V = Desing speed.
G = Gravity.
R = Radios.

Now,
E = (.75 * 20.83)^2/9.81 * 1000,
V = 75 * 1000/60 *60,
V = 20.83m,
E = .2488,
E = .25 approx,
E = 1/40 answer.

Geetha said:   8 years ago
V^2/127R is the formula for super elevation.

We will use use this (V^2/225R )formula only mixed traffic condition is given.

Naren said:   9 years ago
Why we take 1000 as R why don't we take it as the length of the curve? Could anybody please explain me this?

Sharad said:   9 years ago
Let's clear something out first,

e+f=v^2/127r (When V is in kmph) and
e+f=v^2/225r (When V is in mph)

For initial design, we assume mix traffic and hence the velocity reduces to 75% and f is taken as 0.

So, the equation will be e=(0.75v)^2/127r.
Now, the answer will be 0.0249 or 1 in 40.

Rehi said:   9 years ago
Actually, in the problem, it shows that horizontal curve is 1000m but in explanation, they take 1000m as a radius why don't they take it as length of the curve?


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