3.2 TYPICAL CROSS SECTION IN CUTTING AND FILLING – DEFINITION OF ITS ELEMENTS

  

The section of highway perpendicular to its alignment is called cross section of highway.

When formation level of the highway remains at the lower level than that of natural ground profile, in such case, the roadway shall be constructed by cutting the excessive earth material. The cutting can be done by using excavator and earth cutting heavy equipment.

Similarly, when the formation level of the highway is at higher level than its natural ground level, in such case filling of earth mass is required to be done to raise the surface up to formation level. Roads in such case are called embankment roads.

Definition of elements of cross-section

1. Carriage way: The part of highway at which vehicles are used to movement without any disturbance is called carriage way. The width of carriage way depends on the number of lanes.
2. Shoulders: Shoulders are strips provided on both sides of the carriage way. It serves as parking for vehicles when developes some defects and need repairing. Also serve as emergency lane during overtaking small roads. Minimum width of shoulders is 0.75m at each side.
3. Formation width: The total width of roads which contains the width of carriageways, medians and shoulders is called formation width.
4. Side slope in cut and fill: The minimum safe side slope must be provided for cutting and filling portion of road to maintain traffic safety and required stability of soil. For cut 1:1.5 (V:H) and for fill 1:2 (V:H).
5. Center line:  An imaginary line that runs longitudinally along the center of the road.
6. Right of way and clearance: The total width of the roadway which contains present roadway width as well as probable future expansion of highway is called right of way. Row for Highway= 50m, Feeder Road=30m and District Road = 20m.