What is profile levelling, contour, culvert and drainage slope. its type

Profile surveying: -

Profile levelling is generally adopted to find elevation of points along a line such as for road, rails or rivers etc. In this case, readings of intermediate stations are taken and reduced level of each station is found. From this cross section of the alignment is drawn.

Formation Road Level:-

The Formation Level is the level at which excavation ceases and construction commences. It is the lowest point of the path structure. It is the prepared ground on which the sub base layer is laid.

Rise and fall formula.

           For (B.S to I.S)

Rise = IF (B.S>I. S, (B.S-I. S), (0))                        

Fall = IF (B. S<I.S, (I.S-B. S), (0))

            For (I.S to I.S)

Rise = IF (I. S1>I.S2, (I. S1-I. S2), (0))             

Fall= IF (I. S1<I.S2, (I. S2-I. S1), (0))

            For (I.S to F.S)

Rise= IF (I.S>F. S, (I.S-F. S), (0))

Fall= IF (I. S<F.S, (F.S-I. S), (0)

CONTOUR: -

Contouring in surveying is the determination of elevation of various points on the ground and fixing these points of same horizontal positions in the contour map.

Types of Contour Lines in Surveying and their Importance

1. Isopleth

Isopleth on a contour map connects the places having the same value of some measurable quantity of geographical or meteorological phenomena.

For Ex. The population density of an area can be calculated by the quotient of population in the area and surface area of a region.

2. Isohyet

Isohyet indicates the points of equal rainfall of an area in the given time.

3. Isobar

Isobars on contour maps indicates the point of equal or constant atmospheric pressure for a given period.

This type of contour is used in the prediction of future weather patterns isobars are commonly used in television weather reporting.

4. Isobaths

It is a type of imaginary contour lines on a map of chart that connects all the points having same depth below water surface like ocean, sea and lake.

Terrain contour: -

When the terrain is generated by lifting the grid points, the limits of the terrain by the minimum rectangle that contains the plan projection of all contour curves.

Types of terrain contour

·       Plain terrain. For slope, 0 – 10*

·       Rolling terrain. For slope, 10 – 60*

·       Mountainous terrain & hilly.  For slope, > 60*

 CULVERT: -

A small bridge having total length of 6 m or less than 6 m between the faces of abutments is known as culvert. Culvert is a permanent drainage structure mainly constructed to carry roadway or railway track over small streams or channels.

Types of Culverts: -

Following are the types of culverts generally used in construction:

1.     Box Culvert (Single or Multiple)

The culvert consisting of one or more numbers of rectangular or square openings, having their floor and top slabs constructed monolithic ally with abutments and pier, is known as box culvert.

2.     Arch stone Culvert

A pipe arch culvert is a round culvert reshaped to allow a lower profile while maintaining flow characteristics. It is good for installations with shallow cover. Materials used for arch culverts are RCC, Corrugated Metal or Stone Masonry.

3.     Slab culvert

            The culvert, having its superstructure consisting of RCC slab which carries the bridge   floor,                        is known as slab culvert.

4.     HPC- Hume pipe culvert.

           The culvert which consists of one or more pipes placed side by side over a concrete base          below the embankment of a roadway or railway track is known as pipe culvert.

Drainage Slope: -

All of your drain pipe (with one exception) must slope slightly downhill. Usually 1/8" per foot is plenty for drainage, this is the same as the commonly recommended 1% slope.