The following two methods are the methods of setting out simple circular curves by angular or instrumental methods: 1. By Rankine's Tangential Angles. 2. By Two Theodolites. Method # 1. Rankine's Method of Tangential or Deflection Angles: (Fig. 11.14): In this method, the curve is set out by the tangential angles (also known as deflection angles) with a theodolite and [...]
The length of a transition curve may be determined in the following ways: 1. The length may be arbitrarily assumed on the basis of experience and judgement as say, 100 m. 2. The length may be such that the super-elevation is applied at a uniform rate of 1 in 300 to 1 in 1200. If h is the amount of [...]
After reading this article you will learn about the difficulties faced during ranging simple curves. Case I: When the point of intersection of the tangents is inaccessible Fig. (11.17): It so commonly happens that the intersection point (B) becomes inaccessessible due to obstacle like lake, river or wood etc. Let AB and BC be the two tangents intersection at the [...]
After reading this article you will learn about the types and characteristics of vertical curves. Vertical curves are introduced at changes of gradient to avoid impact and to maintain good visibility. These are set out in a vertical plane to round off the angle and to obtain a gradual change of gradient. The vertical curves may be circular or parabolic [...]
The following are the methods of setting out simple circular curves by linear methods and by the use of chain and tape: 1. By ordinates from the Long chord 2. By Successive Bisection of Arcs. 3. By Offsets from the Tangents. 4. By Offsets from Chords Produced. Method # 1. By Ordinates from the Long Chord (Fig. 11.8): Let T1T2=L= [...]
After reading this article you will learn about: 1. Definition of Curves 2. Classification of Curves 3. Various Parts 4. Elements 5. Designation 6. Methods 7. Transition Curve. Definition of Curves: Curves are regular bends provided in the lines of communication like roads, railways etc. and also in canals to bring about the gradual change of direction. They are also [...]