Back Side,Fore Side,RL, BM, Leveling And Contouring ~ Civil Engineer Knowledge

SURVEYING( Part 3)

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LEVELING AND CONTOURING

REDUCE LEVELING-

The vertical distance of a point above or below a datum on earth surface is called level or Reduce level.

BACK SIDE-

If elevation of a station A is known then the staff reading on station A is called as Back Side.

FORE SIDE-

If elevation of station B is to be determined , then the staff reading on station is called as fore side.

BENCH MARK-

A fixed reference point of known elevation is called Bench Mark. Great Trigonometric Survey(GTS) bench mark taken as mean sea level at Bombay Port.

TYPES OF LEVELING
1. Simple Leveling-
This is the leveling when it is required to find the difference in elevation between two points both of which are visible from a single position of the level.

SIMPLE LEVELING

2. Differential Leveling-

This is the process mesuring vertical distance from a known elevation point to determine elevations of unknown points.

DIFFERENTIAL LEVELING

3. Fly Leveling-

In order to connect bench mark to the starting point of the aligment of any project, it is called Fly Leveling.

FLY LEVELING

4. Longitudinal Leveling-

The operation of taking Levels along the center of any alignment at regular terms is known as Longitudinal Leveling.

LONGITUDINAL LEVELING

5. Cross-Leveling-

The operation of taking traverse to direction of longitudinal leveling is called Cross-Leveling.

CROSS LEVELING

6. Check Leveling-

At the end of the day's work to connect the finishing point with the starting point on the particular day is known as Check Leveling.

CHECK LEVELING

7. Reciprocal Leveling-

Two widely separated points in which observations are made in both directions to eliminate the effects of atmospheric refraction and the curvature of the earth.

RECIPROCAL LEVELING

CONTOURING

The purpose of tracking contour lines on the surface of the earth is called Contouring.

Purpose of Contouring -

a. For preparing contour maps in order to select most economical or suitable site.

b. To locate alignment of a canal so that it should follow ridge lane.

c. To marks alignment of roads and highway so that the quantity of earthwork both in cutting and filling should be minimum.

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