Month: April 2019

Convert Quadrantal Bearings to Whole Circle Bearing -Example

Convert Quadrantal Bearings to Whole Circle Bearing

Convert the following quadrantal bearing into whole circle bearing:

1. N 30°30՛ E
2. S 50° E
3. S 20°45՛ W
4. N 25° W

Solution:

How to draw the line for a Q.B ??

For Example: N 30°30՛ E, S 20°45՛ W & for N 25° W.

In case of N 30°30՛ E, the line will be drawn starting from the North line up to 30°30՛ towards the East line.

In case of S 20°45՛ W, the line will be drawn starting from the South line up to 20°45՛ towards the West line.

In case of N 25° W, the line will be drawn starting from the North line up to 25° towards the west line.

Now, the whole circle bearing can be written directly as below:

1. Line OB, W.C.B = 30°30՛

Convert Quadrantal Bearings to Whole Circle Bearing image 1

2. Line OC, W.C.B =180° – 50° = 130°

3. Line OD, W.C.B = 180° + 20°45՛ = 200°45՛

4. Line OE, W.C.B = 360° – 25° = 335°

How To Calculate True Bearing From Magnetic Bearing

Convert The Whole Circle Bearing to Reduced Bearing – || Rules and Example ||

Convert Whole Circle Bearing to Reduced Bearing Rules

1. When Whole Circle Bearing(W.C.B) lies between 0° to 90°.

Reduced Bearing(R.B) = W.C.B

2. When W.C.B lies between 90° to 180°.

R.B = (180° – W.C.B)

3. When W.C.B lies between 180° to 270°.

R.B = (W.C.B – 180°)

4. When Whole Circle Bearing(W.C.B) lies between 270° to 360°.

Reduced Bearing(R.B) = (360° – W.C.B)

Example of Convert Whole Circle Bearing to Reduced Bearing

Example:

Convert the following whole circle bearing to reduced bearing(with quadrant)
a. 30°
b. 160°
c. 200°
d. 315°

Solution:

Convert The Whole Circle Bearing to Reduced Bearing

For 30°, Reduced Bearing(R.B) = 30° NE
For 160°, R.B = (180° – 160°) = 20° SE
For 200°, R.B = (200° – 180°) = 20° SW
For 315°, R.B = (360° – 315°) = 45° NW. Where, NE, SE, SW, NW is the quadrant.

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Convert Quadrantal Bearings to Whole Circle Bearing

Numerical Example For Error Due To Wrong Measuring Scale – Survey Engineering

Numerical Example For Error Due To Wrong Measuring Scale

Following numerical example shows that how to calculate correct length and area, if errors occur due to wrong measuring scale:

Numerical Example

A surveyor measured the distance between two points marked on the plan drawn to a scale of 1cm = lm (R.F. = 1: 100) and found it to be 60m. Later he detected that he used a wrong scale of 1 cm = 50 cm (R.F. = 1: 50) for the measurement.

(a) Determine the correct length.
(b) What would be the correct area if the measured area is 70 m²?

Mathematical Solution

a. Correct length = (R.F. of the wrong scale/R.F. of the correct scale) ⨯ measured length = [(1/50)/(1/100)] ⨯ 60 = 120m.

b. Correct area = (R.F. of the wrong scale/R.F. of the correct scale)² ⨯ measured area = [(1/50)/(1/100)]² ⨯ 70 = 280 m².
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7 Uses Of Surveying

Surveying may be used for the following various purpose:

1. Engineering Surveying

Engineering surveying is used for the design and construction of a new project such as road, railway, building, city, towns etc.

2. Topographical Surveying

To prepare a topographical map, which shows the hills, rivers, valleys, forest, village, towns, etc. of a country.

3. City Surveying

City surveying, which is used to locate the streets, water supply, sanitary system etc.

4. Cadastral Surveying

Cadastral surveying, which is conducted in order to produce plans of property boundaries for legal purpose.

5. Astronomic Surveying

Astronomic surveying is used to determining latitudes, longitudes, azimuths, local time etc. for the various places on the earth.

6. Geological Surveying

To prepare a geological map, which shows the information about different strata of the earth surface for the purpose of the geological studies.

7. Photogrammetric Surveying

Photogrammetric surveying is used for obtaining topographical details of large areas which are difficult to access.

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Quantity Of Soil Sample Required For Different Test

The following tests and required sample weight are:

i) Soil identification, natural moisture content test, mechanical analysis and index properties chemical test

⇛ For Cohesive Soils – Required sample weight is 1 kg

⇛ For Sand and gravels – Required sample weight 3 kg

ii) Compaction tests

⇛ For Cohesive Soils and Sands – 12.5 kg

⇛ For Gravelly Soils – 25 kg

iii) Comprehensive examination materials including soil stabilization

⇛ For Cohesive Soils and Sands – 25 to 50 kg

⇛ For Gravelly Soils – 50 to 100 kg

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Method Of Providing Superelevation

Introduction of superelevation on a horizontal curve of a road is an important feature in road construction. Superelevation is provided in the following two methods.

Elimination of the crown of the cambered section.
Rotation of pavement to attain full superelevation.

1. Elimination of The Crown of The Cambered Section

In this method, the outer half of the camber is gradually decreased. This may be done by two methods.

In the first method, the outer half of the camber is rotated about the crown at the desired rate such that the surface falls on the same plane as the inner half.

Elimination of The Crown of The Cambered Section

In the second method, the crown is progressively shifted outwards. This method is not usually adopted.

Second method of Elimination of The Crown of The Cambered Section

2. Rotation of Pavement To Attain Full Superelevation

In this stage, superelevation is gradually provided over the full width of the carriageway so that the required superelevation is available at the beginning of the circular curve. The different method employed for attaining the superelevation is as follows:

A. Revolving Pavement About The Center Line

In this method the surface of the road is rotated about the center line of the carriageway, gradually lowering the inner edge and rising the upper edge. The level of the center line is kept constant. This method is widely used.

B. Revolving Pavement About The Inner Edge

In this method, the surface of the road is rotated about the inner edge, raising the center and outer edge.

C. Revolving Pavement About The Outer Edge

In this method, the surface of the road is rotated about the outer edge depressing the center and inner edge.

Maximum And Minimum SuperElevation As Per I.R.C

5 Types of Road Tar

What is Road Tar?

Tar is the viscous liquid obtained by the destructive distillation of coal or wood in the absence of. Generally, the colour of the road tar is black and it contains 72 to 96% bituminous contents.

Types of Road Tar

There are 5 types(grades) of road tars viz RT-1, RT-2, RT-3, RT-4, RT-5 based on their viscosity and other properties.

RT-1 has the lowest viscosity and used for surface painting under exceptionally cold weather. The specific gravity of this road tar is 1.26.

RT-2 is recommended for standard surface painting under normal Indian climate condition. Specific gravity 1.26

RT-3 may be used for surface painting, renewal coats and premixed top course and light carpets. The specific gravity of this tar is 1.28

RT-4 is generally used for premixing tarmacadam in base course. Specific gravity 1.28

RT-5 has the highest viscosity and may be used for grouting purpose. Sp.g 1.28.

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Factors Affecting The Thickness Of A Load-Bearing Wall

The thickness of a load-bearing wall shall be sufficient to ensure that in worst condition loading, the stresses developed are within the safe limits.

The thickness of a non-load-bearing wall should be sufficient to ensure stability and strength against lateral forces.

The thickness of a wall depends on the following factors:

1. The loads carried by the wall such as dead load, live load, wind load, seismic forces, and the amount of eccentricity (if any).

2. The overall height of the wall.

3. The height of the wall between floors.

4. The overall length of the wall and the centre-to-centre distances between lateral supports.

5. The crushing strength of bricks to be used and the strength of the mortar to be applied.

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Prevention of Dampness

There are various methods of damp proofing. Adoption of any specific method depends upon various factors such as

―nature of the surface,
―location of the structure,
―sub-soil water table,
―the amount of dampness to be handled, etc.

Following are the methods or measures adopted to prevent dampness:

1) Surface treatment.
2) Integral waterproofing.
3) Incorporation of a membrane between the source of dampness and the part of the building adjacent to it.
4) Construction of cavity wall.
5) Guniting.

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