Transportation Engineering Part I

Transportation Engineering Part I

Design of Horizontal Alignment

Change in the direction are required in highways alignment due to the various reason 

  1. Topographic condition

  2. Oscillatory points

Various design elements to be considered in the horizontal alignment are

  1. Design speed 

  2. Radius of circular curve

  3. Types and length of transition curve 

  4. Width of pavement

  5. Superelevation

  6. Set back distance

  • Design speed

The design speed is the main factor on which most of the geometric design elements depends including horizontal alignment

The design speed of road depends upon class of road and terrain

  • Classification of terrain & design sped for different class of road is as follows

Design speed are also designed for urban roads

  • Two values of speed are ruling & minimum are being specified for each type of road.

  • As far as possible, attempts must be made to design all the geometric elements for ruling speed, however if site conditions are economic consideration does not permit so designing must be done for minimum design speed.