Unit 1: Introduction

Estimating & Costing II

Unit 1: Introduction

1.1.  Terms used in Earthwork in road construction

1.      Road alignment Survey

The road alignment survey is a process used to determine the most suitable route for a new road. It involves collecting data and conducting measurement to determine the best path for the road. The survey helps in designing the road alignment & creating detailed plans for construction.

2.      Plan of road alignment

After road alignment survey, we find center line of road. The required width is provided which shown by plan. The top view of road is called plan of road alignment. Plan give the horizontal movement of road. Like: straight, bend, no. of curves etc.

3.      Chainage:

Distance travelled along the center line of road up to particular point is called chainage. The reference point is typically a starting point, such as the beginning of the road. The chainage is usually measured in units such as meters or kilometers.

4.      Longitudinal section (L-section of Road)

A longitudinal section of a road is a graphical representation that shows the road profile along its length, typically from one end to other. It provides a detailed view of the road's elevation changes. L-section shown a line and various features such as curves, grades, intersections etc.

5.      Cross section: (X-section of Road)

A cross-section of road refers to a vertical view of the road, typically shown in a diagram. It provides a detailed representation of the different layers and components that make up the road structure from top to bottom.

6.      Ground level (GL)

Ground level is existing ground or natural ground which is shown in section.

7.      Formation Level (FL)

Formation level is the desired level or profile of the road bed during construction. It represents the prepared subgrade of the road before the addition of any pavement layers.

During road construction, the formation level is established by cutting or filling the natural ground.

8.      Cutting

Cutting is the process of excavating or removing the existing soil or rock from the road bed and creating the desired road profile.

9.      Filling/Banking

It is also known as embankment. It involves adding or placing suitable material, such as earth, gravel or crushed stone, to raise the ground level & create the desired road profile.

10.  Volume of E/W

The volume of earthwork is the total volume of material that is excavated or filled during a road construction. It is measured in Cubic meters (m³). V = A × L

11.  Balancing E/W

Balancing earthwork is the process of redistributing excavated soil & other materials within the construction site to achieve a balanced cut & fill.

The goal is to minimize the need for importing or exporting excess material, thus reducing costs & environmental impact.

12.  Lead

Lead is the horizontal distance travelled by the earth to be moved for banking of dumping. It is normally 30m.

13.  Lift

Lift is the vertical distance travelled by the earthwork after excavating. It is normally 1.5m.

14.  Burrow pit

Borrow pit is an pit formed by excavation of material, like soil, gravel or sand from side of road. These materials are used for embankments, subgrade of other road construction purposes.

15.  Spoil Bank

The excess soil or materials that are excavated from the road bed or cut slopes are deposited nearby, forming a spoil barık.