Transition curves - geometric design of roads, Civil Engineering

Transition Curves:

If a vehicle travelling on a straight enters a horizontal curve abruptly, it will cause shock and sway. To avoid this, it is customary to provide a transition curve (Figure). Incidentally, the transition curve is also used to provide gradual application of super- elevation and widening of the curve. A spiral is the most commonly used transition curve.

990_Transition Curves.png

Figure: Main Elements of a Circular Curve Provided with Transitions

Some of the important properties of the spirals are given below :

(a)        Ls Rc = LR = constant

(b)       L = M√ θ , where M is a constant

M =     √2RL

Also, L = 2 Rθ

(c)   θ= (L/Ls)2    θs

(d)  θs = Ls/2Rc    radians =    28.65 Ls/Rs degrees

(e) Ts = Ls/2 +(Rc+s)tan(Δ/2)

(f) s= Ls2/24Rc

(g) Es= (Rc+s)sec Δ/2-Rc

 The following nomenclature may be noted:

θs         :           Spiral angle

Δc        :           Angle of the circular curve

Δ         :           External angle

Ls         :           Spiral Length

Rc        :           Radius of circular curve

L          :           Length of spiral from starting point to any point

R         :           Radius of curvature of the spiral at the point distant L from starting point

θ          :           Deflection angle at any point of the spiral distant L from the starting point

Ts        :           Tangent distance

Es        :           Apex distance

s          :           Shift

HIP     :           Horizontal Intersection Point

BS        :           Beginning of spiral

BC       :           Beginning of circular curve

EC       :           End of circular curve

ES        :           End of spiral

Posted Date: 1/22/2013 2:33:31 AM | Location : United States







Related Discussions:- Transition curves - geometric design of roads, Assignment Help, Ask Question on Transition curves - geometric design of roads, Get Answer, Expert's Help, Transition curves - geometric design of roads Discussions

Write discussion on Transition curves - geometric design of roads
Your posts are moderated
Related Questions
Hi I am looking for someone who can help to solve my assignment questions in a subject called project costing and I need him to continue with me until I complete this subject. I a

what is end condition how effected length is calculated

sample problems with solutions for probable value

Q. Write short notes on Aqua Privy Latrine? There are a sort of latrines also called septic tank latrines. These are constructed over septic tanks & flushing is also provided.

industrial applications of ultrasonic welding,soldering,drilling,claning

Define the Cost of shock transmission unit? There is a keen competition among the few STU manufacturers. For the second Bassein Creek Bridge, the average cost of two STUs of ca

what are the roles of civil engineers in storm water management


Calculate the ultimate compressive strength A 6 in. by 12 in. cylinder failed at an axial compressive force of 120,000-lbf, at 28 days. Calculate the ultimate compressive stren

Define Concrete Surface Finish - Limitations of Ultrasonic System? The smoothness of the surface under test is important to ensure proper acoustical contact between the transdu