# Transition (spiral) Curves

Posted in Highway Engineering | Email This Post |While taking a turn,the centifugal forces develop so a vehicle and its contents are immediately subjected to centrifugal forces. More is the speed of vehicle sharper is the curvature and thus the greater the influence on vehicles and drivers of the change from tangent to curve. When transition curves are not provided, drivers tend to create their own transition curves by moving laterally within their travel lane and sometimes the adjoining lane,which is risky not only for them but also for other road users.

Mathematically

The minimum length L, ft (m), of a spiral may be computed from

L=3.15V^{3}/RC

where

V =vehicle velocity, mi/h (km/h)

R= radius, ft (m), of the circular curve to which the spiral is joined

C= rate of increase of radial acceleration

An empirical value indicative of the comfort and safety involved, C values often used for highways range from 1 to 3.

I want to know details of Transition Curve in highway (combined in circular)

Dear Tapas,

Please go through IRC 38 & 73 and everything will be clear to you about Transition Curve

What’s IRC 38 & 73? How can I find IRC 38 & 73 on the net? (I searched but I have found nothing.)

I wanna get a detailed book in transportation engg. where geometric design of highway is available.

I want to know details description of Transition Curve,circular curve,horizontal curve.. in highway.

How can I select or assume the appropriate C value

whithout recommended schedule or equation depends on

speed changeable .so could I the required information to

determine or select the rate of increase of radial acceleration .

Full thanks

Greetings to you,i’d like to compute or give me the formulas of concrete road with all details from foundation to the end.

thank you a lot

I want to know the calculations and formulas involving in a flexible pavement road from start to end …….regards

Sir ,

According to IRC,

1)Allowable rate of change of centrifugal acceleration (I),

For speed less than 32kmph,I-0.76

,, ,, exceeding 96kmph I-0.46

And for speed in the range 32-96 kmph I-73/(V+96)

2)I-80/(75+V) and value lies between 0.5 to 0.8.

Sir in two different books i saw two different cases.Which one is true? and what is the

Difference?

I have master degree in civile engenering and I would like to work in usa, where can I inform myselve about that. Sorry for my bad eng.

And how to sign in for PHD on your faculty?

and sorry for interopting but for all roads everything is how u calculate curve (Bs+radius R) and if u combine that no problem in any curve on the road.

U are talking about some simple things there are 10 ways for every problem ( on u is to deside which is the best for u)

My best regards for all of u

In which cases is it advisiable to use a transition curve, but not a circular curve?

I’m doing land surveying, would like to much about transition curves. so my you help with somemore notes

sir as per irc codal provision min 150 m curve length is to be provided at deviation angle more than 5 d this 150 m length includes spiral curve length with curve length or we can make cicular curve length zero