Design of Horizontal Alignment
Change in the direction are required in highways alignment due to the various reason
Various design elements to be considered in the horizontal alignment are
Radius of circular curve
Types and length of transition curve
Width of pavement
Set back distance
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.