### Discussion :: Highway Engineering - Section 1 (Q.No.1)

Yugananth P said: (Aug 26, 2013) | |

e = V^2/225R. = 75 * 75/(225*1000). = 1/40 (or). = 1 in 40. |

Arnab Chanda said: (Mar 23, 2014) | |

But it is not declared that 1000 m is the radius of the curve. |

Muleta Totoba said: (Mar 24, 2014) | |

Right it is not declared but the term curve seems something to be the given figure 1000 is the radius. |

Surya said: (Aug 2, 2014) | |

e = V^2/gR. V = 75% of design speed. V = 0.75*75. v = V/3.2. |

Jay Mishra said: (Aug 28, 2014) | |

I think superelevation = v^2/127r. |

Deepak Mittal said: (Sep 17, 2014) | |

No it should not be v^2/127r. If the value of f then you can take the v^2/127r. Otherwise V^2/225R. |

Biswa said: (Nov 17, 2014) | |

e = (0.75v)^2/Rg. v in m/s. Ans: 1 in 40. |

Reshma said: (Dec 3, 2014) | |

We have to design for 75% speed means super elevation for mixed traffic. So, e = (0.75V)^2/gR = V^2/225R. |

Anitha said: (Dec 26, 2014) | |

We have to design for 75% speed. So, e = (0.75v)^2/g.r; v = 75kmph = 75/3.6 = 20.833. e = (0.75*20.833)^2/(9.81*1000) = 0.02488. 1/40 = 0.025. |

Shankar Meghwar said: (Jan 24, 2015) | |

R = V^2/225(e+fs). Consider coefficient of friction as fs = 0. Therefore R = V^2/225 e. OR e = V^2/225 R. = 75*75/(225*1000). = 0.025. OR = 1 in 40. |

Manoj Kumawat said: (Feb 24, 2015) | |

According IRC : The super-elevation is calculated for 75% of design speed. So e = V^2/225R. |

27-27 said: (Mar 14, 2015) | |

Design speed is given use: e = (0.75v)^2/gR. In a question if they are given only speed then use: e = v^2/gR. |

Aditya said: (Jun 26, 2015) | |

Guys can you please tell me the density of GSB, WMM, DBM and also BC? |

Banoth Ramesh said: (Aug 3, 2015) | |

ANS (A). e = V^2/225R. e = 0.025 = 1 in 40. |

Ram Kumar said: (Oct 10, 2015) | |

e = v^2/(127R) this formulas use. And get the super elevation. |

Pratik said: (Oct 13, 2015) | |

Radius is not mentioned. |

Mohamed Yaagob said: (Jan 30, 2016) | |

F = 0 V = 0.75 V design speed. E = (0.75 V)^2/(127 R). |

Prashant said: (Feb 24, 2016) | |

1000 m is length of curve here, not radius. |

Ies Akp said: (Apr 1, 2016) | |

1000 m is radius, it can't be length because there is no relation to provide length. |

Osi said: (Jun 21, 2016) | |

But we have studied it in the formula = v^2/126R. I am confusing which one is correct. |

Miki said: (Jul 30, 2016) | |

Both the formula is correct, the only difference is in e = v^2/127R, uses 75% of speed, and in e = V^2/225R, we are directly used. |

Ravindra said: (Aug 21, 2016) | |

The given answer is true, don't confuse it. |

Jatav Shurjeet Singh said: (Sep 2, 2016) | |

It is the right answer, it will use v^2/225r. |

Jack said: (Sep 8, 2016) | |

A District road having the mixed traffic condition so speed is reduced by 25%. Super elevation e = V^2 / 225 R. e = 75 * 75/225 * 1000 = 0.025. so for 1m, 1/0.025 = 40. => 1 in 40. |

Shailendra Kumar said: (Oct 9, 2016) | |

I think the formula of superelevation e= v^2/225R. So we put all values as given in the question e = 75 * 75/225 * 1000. e = 1/40. |

Kruti Nayak said: (Oct 17, 2016) | |

v^2/225R is correct. v^2/127R when f = 0. |

Joel said: (Oct 17, 2016) | |

The provided answer 1 in 40 is correct. |

Happy said: (Dec 1, 2016) | |

But, here v^2/225 is the highest unit of super-elevation. |

Mukeah Senani said: (Dec 13, 2016) | |

E = V^2/225R -> this method is Right. |

Jayrajsinh said: (Dec 14, 2016) | |

Practically super elevation e = v^2/225R. So answer 1 in 40 is correct. |

Sonu said: (Dec 19, 2016) | |

If f is not given so we apply e = v^2/225R . The answer is 1 in 40. |

Titan said: (Dec 21, 2016) | |

Why is everyone assuming R=1000? I think the curve length is 1000, not R. And the angle is not given. |

Yohannis said: (Jan 12, 2017) | |

The question stated that 75km/hr is design speed, thus simply we can calculate e=(75^2)/225R. b/c 'f' is not given. There fore, 1:40 is the correct answer. If 'f' were given, we use (e+f) = (75^2)/127R. |

Danjah said: (Jan 14, 2017) | |

here 1000 m is the length of curve, not radius. |

Haylee Ethio said: (Feb 19, 2017) | |

Well, We Have, R=1000m V= 75Km/h Required? Superelevation(e) e=v^2/225R = 75^2/225(1000) =1/40 is the Correct one. |

Rehi said: (Feb 24, 2017) | |

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? |

Sharad said: (Apr 2, 2017) | |

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. |

Naren said: (Apr 3, 2017) | |

Why we take 1000 as R why don't we take it as the length of the curve? Could anybody please explain me this? |

Geetha said: (Apr 4, 2017) | |

V^2/127R is the formula for super elevation. We will use use this (V^2/225R )formula only mixed traffic condition is given. |

Palash Mondal said: (Apr 8, 2017) | |

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. |

Babugouda said: (May 5, 2017) | |

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

Sameer Naik said: (Jun 28, 2017) | |

Why used 75% in que not mention mixed traffic? |

Rajesh Kumar Saini said: (Aug 19, 2017) | |

1/40 is the right answer. |

Harveer Singh said: (Aug 26, 2017) | |

1 in 40 is the right answer. V^2/125r ( f is not given). |

Yamir said: (Aug 28, 2017) | |

F is not gives that doesn't mean we will not use 127 Maximum times we use 127 for already designed roads. |

Azanaw said: (Sep 13, 2017) | |

Why 75% is taken for design speed? |

Janardhan said: (Sep 16, 2017) | |

e=V2/225R when V in KMPH, e=v2/127R-f ,if f is given, and v in m/s,other wise e=v2/127R if f is not given. |

Himanshu Kumar said: (Sep 29, 2017) | |

But there speed in kilometer and horigental curve in meter so how it is possible? Please explain. |

Deven Negi said: (Oct 26, 2017) | |

Radius are not mentioned. |

Manish Chandel said: (Jan 4, 2018) | |

e=v^2/225*R is correct. |

Dj.Thakur said: (Jan 15, 2018) | |

For design of superelevation on road:- (1)- design superelevation for 75% of design speed. (Hence s.e. resists 75% of centrifugal force rest is balanced by road friction) |

Haroon said: (Mar 4, 2018) | |

e+f=v^2/gr, v in m/s. e+f=v^2/127r, v in km/h. For 75% of design speed f=0,as per irc. e=(0.75v)^2/127r =v^2/225r. e=75*75/(225*1000)=0.025=1:40. |

Anmol said: (Jul 2, 2018) | |

It's we have already given the design speed so we will use v2/127r. |

Dev said: (Aug 15, 2018) | |

Here it's v^2/127r. |

Anwar Zaib said: (Sep 1, 2018) | |

To determine super elevation we need only f- value, design speed and radius of the curve. So, if it is not mentioned then directly take the value with the unit of distance i.e meter. the formula for mix traffic. e + f = V^2/225R HERE f = 0 R=1000m and V =75kmph so e= 0.025 (1/40). |

Surafel Belayneh said: (Sep 13, 2018) | |

A District road having the mixed traffic condition so speed is reduced by 25%. Super elevation e = V^2/225 R. e = 75 * 75/225 * 1000. = 0.025. So for 1m, 1/0.025 = 40. => 1 in 40. |

Yash said: (Nov 19, 2018) | |

Already design speed is given, then why it converted again to design speed? Please tell me. |

Sonam Phuntsho said: (Jan 6, 2019) | |

What is the location of the road is on hilly area? |

Mayur said: (Jan 24, 2019) | |

Use e= (0.75v)^2/gr. |

Singh Bushan Chib said: (Mar 6, 2019) | |

It is right 1/40 by using the formula. |

Rahul said: (Apr 19, 2019) | |

In this question clearly mentioned design for the road not for any particular vehicle. In the design of road assume friction is zero and 75% velocity ie formula of e is v^2/225R. |

Tabaamith said: (May 12, 2019) | |

Convert 75km/hr to m/ sec, which comes 20.85m/sec. Take velocity as 75% of design speed. Now, e= (0.75 * 20.85)^2/ 9.81X1000 = 0.024. In ratio 1/1/0.024 = 1 in 40. |

Kara Lala said: (May 20, 2019) | |

GSB - Granular Sab Base. WMM - Wet Mix Macadam. |

Arjun said: (Sep 16, 2019) | |

Design superelevation is always taken as 75% of the Design Speed hence it is e = v^2/225R. |

Mohammed said: (Nov 6, 2019) | |

@Azanaw. You will find a clear explanation in IRC 38 codebook. However, I will try to briefly summarise it to you. Basically superelevation is provided to counteract the centrifugal force experienced by a vehicle when it's negotiating a curve. Now counteracting the full centrifugal force developed for a given design speed would require us to provide superelevation of more than 7%. But IRC restricts the maximum value of e= 7%. So in practice for mixed traffic, most vehicles travel at less than design speed (where we have both slow and fast-moving vehicles) so as a compromise since we can\'t provide the actual value we design superelevation to resist the full centrifugal force developed at 75% design speed. Eg: If the design speed of a National Highway is 80kmph. We design the superelevation to fully resist the centrifugal force developed due to 75% of 80kmph = 60 kmph. This method of giving superelevation will not be inconvenient to fast-moving vehicles but would be of aid to slow-moving vehicles. |

Ramkishor Sahu said: (Dec 16, 2019) | |

Superelevation is always. e+f=v^2/127R. But for the design of the superelevation we take, e=V^2/225R. So, Here velocity 75 kmph and horizontal curve 1000 meter given. That means it is the radius of the horizontal curve. Note:- Horizontal curve always given in the form of the radius. Put these values to find the horizontal curve, e = 75^2 / (225*1000). e = 1/40. Thank you. |

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