Comments on: Super Elevation and How to Calculate it

By: Vikrant Mane

Vikrant Mane — Wed, 21 Aug 2024 12:36:49 +0000

In reply to Varadharajan. In your case, with a total curve length of 77 meters and transition lengths of 72 meters on each side (totaling 144 meters), the transition curves would overlap or completely occupy the curve length, leaving no room for the circular arc. This situation is not possible in practical design. Here’s what can be done:

Re-Evaluate the Curve Design:

1. Transition Length Adjustment: Consider reducing the transition lengths to fit within the 77 meters. However, keep in mind that this may impact the curve's design speed and overall safety. 2. Increase Curve Length: If possible, extending the total curve length (tangent to tangent) would allow for the required transition lengths while still accommodating the circular arc.

Minimum Circular Curve Length:

Ideally, after deducting the transition lengths, there should be a remaining length for the circular curve. If not, the curve design might need to be adjusted to ensure safety and functionality. It's crucial to balance transition lengths and the circular curve within the available space to maintain the curve's integrity and ensure a safe design. Note: It's crucial to consult with a road engineer or site engineer who is familiar with the specific site conditions. They can provide detailed guidance tailored to the actual terrain, traffic, and design requirements.

By: Varadharajan

Varadharajan — Tue, 20 Aug 2024 15:08:44 +0000

My total curve length (i.e tangent to tangent) itself is 77m only. But i get length of transition as 72m. How can i provide transition on both sides (i.e 144m) in 77m total length of curve.? How much should be minimum length of Horizontal or actual curve without (after deducting) transition length?

By: vicky

vicky — Fri, 29 Mar 2024 12:56:58 +0000

In reply to steven dzama. Do you mean how to simplify this: (v/3.6)^2 / g.R

By: steven dzama

steven dzama — Sun, 03 Mar 2024 16:47:59 +0000

In reply to vicky. how did you solve to multiply 3.6square with gR?

By: vicky

vicky — Wed, 03 Jan 2024 11:58:39 +0000

In reply to Zaw Lwin Oo. Yes, to convert the value from km/h to m/s, you have to divide the speed value by 3.6, which is a constant. Alternatively, you can also convert the value by multiplying it by 0.28. Both methods are correct.

By: Zaw Lwin Oo

Zaw Lwin Oo — Wed, 03 Jan 2024 07:56:48 +0000

In reply to vicky. it mean, is 3.6 constant? Regards

By: vicky

vicky — Tue, 31 Oct 2023 12:45:23 +0000

In reply to Ahmed maher. If you have your road width and radius dimensions in feet then convert it to meter before using this formula. These formulas are standard for meter/kmph units.

By: vicky

vicky — Tue, 31 Oct 2023 12:39:01 +0000

In reply to Ahmed maher. are you talking about the radius unit?

By: Ahmed maher

Ahmed maher — Mon, 30 Oct 2023 18:35:34 +0000

I want to conclude it with feet

By: Ada Jamaima C Tampus

Ada Jamaima C Tampus — Sun, 14 May 2023 13:23:41 +0000

In reply to vicky. Thank you so much for explaining!

By: vicky

vicky — Thu, 09 Feb 2023 12:30:42 +0000

In reply to moses.

In both the formulas,

e + f = v² / g.R ...(eqn 1)

e + f = V² / 127.R ...(eqn 2)

The value of g = 9.81 m/s² in both the formula and this will not change. Just to simplify the formula the value of acceleration due to gravity (g) is multiplied by the the converting factor of 'kmph' to 'm/s'.

You can use the first equation when the speed of vehicle is in 'm/s', but generally the speed of vehicle is mentioned in 'kmph', so you have to use the second equation in this case. In second equation the value of 'V' i.e speed of vehicle is converted to 'kmph'. Below we have explained how the value 127 has been occurred in the formula.

e + f = v² / g.R

The convert the value from kmph to m/s, the speed value must be divided by 3.6.

In the above formula we have to convert the value of 'v' from kmph to m/s. To do this we have to divide the speed value by 3.6 and simplify the formula.

e + f = (v/3.6)² / g.R
e + f = V² / (3.6)².g.R
e + f = V² / 12.96*9.81.R
e + f = V² / 127.R (after multiplying 12.96*9.81 we get 127.1376. Round off the value to whole number)

This is how you get the value 127 in the super elevation formula used for the speed of vehicles in kmph.

By: moses

moses — Mon, 06 Feb 2023 13:06:04 +0000

if g is equal to 9.81m/s2 how do we get 127 in the formula?

By: Jim

Jim — Sat, 15 Oct 2022 03:03:21 +0000

In reply to Vijayan M. g is the force due to gravity. 32.6 ft/sec/sec in English units

By: vicky

vicky — Sat, 16 Jul 2022 13:02:37 +0000

In reply to Vijayan M. 'g' is represented as the 'acceleration due to gravity (9.81 m/s^2)'. The formula (e+f= v^2/g.R) is used for the problems when the speed of the vehicle is in 'm/s'. But generally the speed of the vehicles is calculated in 'kmph', hence we use the formula (e+f= v^2/127.R)

By: Vijayan M

Vijayan M — Thu, 14 Jul 2022 13:09:01 +0000

In this equation what is ‘g’, it is not explained. Please explain.