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  2. W 90°
  3. What is the definition for open traverses?
  4. How can we get angle value. Can u explain it deeply please?
  5. helpful and learn from it.
  6. The direction will be exactly towards west. Hence, no reduced bearing in this case.
  7. reduced bearing N90W or S90W
  8. Meridian Meridian is a reference direction with respect to which the direction of lines are mentioned. There are three types of meridian - True Meridian, Magnetic Meridian & Arbitrary Meridian 1 - True Meridian It is the reference direction of north pole of earth from a given station point. It is also called geographic meridian. 2 - Magnetic Meridian It is the direction of north pole indicated by magnetic needle. 3 - Arbitrary Meridian This is any assume direction to a well defined object. It may be useful for small areas. e.g A mosque is taken as reference and location of road will be mentioned with respect to this mosque. Direction of magnetic north with respect to true north is called magnetic direction. Bearings Bearing is the angle which a certain line make with a certain a certain meridian. Bearing with respect to true meridian is called true bearings while magnetic bearing is the angle which a line makes with respect to magnetic meridian. There are two ways to represent the bearings, Whole circle bearing (W.C.B) Reduced Bearing (R.B) 1) Whole Circle Bearing (W.C.B) It can be taken 0° to 360°. Quadrants are taken clock-wisely and angles are also determined in clockwise direction. 2) Reduced Bearing Reduced bearing or Quadrantal bearing is the angle which a line makes from North or South Pole whichever may be near. It is value is from 0° to 90°. Using the above figures you can easily convert the Whole Circle Bearing into Reduced Bearing. Some Examples are given are below. Whole Circle Bearing (W.C.B) Reduced Bearing (R.B) 135° S45E 37° N37E 65° N65E 125° S55E 215° S35W 300° N60W
  9. Angle measurement For angle measurement with theodolite vertical hair is used. Basically there are two methods horizontal angle measurement, Repetition method (For single angle) Reiteration method (For more than one angle) 1 - By Repetition method Let suppose it is desire to measure the angle A from the following figure. We will use repetition method for this purpose. Procedure Setup the theodolite at station A. Bisect the point B with vertical hair of theodolite and move telescope in clockwise and direction to bisect at point C. Note this circle reading in the book and fix this circle reading, then again bisect the point B by keeping the circle reading fixed. Now, release the circle reading and rotate the telescope again in clockwise direction till it bisect again point C. Similarly get 3rd and 4th repetition and note the circle reading after 4th repetition in the book. Change the face of telescope and repeat the above steps, an example and method of booking observations have given below, Inst. Station Angle Face Repetition Circle Reading (° ′ ″) Angle value(° ′ ″) Mean of faces (° ′ ″) A BAC L 1 25 20 00 25 20 10 25 20 9.5 4 101 20 40 R 1 25 20 03 25 20 09 4 101 20 36 2 - By Reiteration method This method is used if there are more than one angles to be measure from a certain station point. Consider the following fiqure, we will measure angles AOB and BOC using this method. Procedure Setup the theodolite at station O, bisect the point A with a certain circle reading with face left. Rotate the instrument in clockwise direction and bisect B, note the circle reading. Then rotate and the telescope till it bisect the point C, note this circle reading also. All these reading will book into face left position. Transit the telescope and rotate the instrument through 180°, this time bisect the point C firstly and then rotate telescope in anti clockwise direction towards B and then ultimately towards A. Put these readings in face right position. You can do more than one sets of measurements for the accurate results, i have done one set and booking method is as follows, Inst. Station Stn. Sighted Face Circle reading(° ′ ″) Mean of faces(′ ″) Angle value(° ′ ″) O A L 10 20 05 20 06 AOB 37 10 05 R 190 20 07 B L 47 30 10 30 11 R 227 30 12 BOC 41 10 14 C L 88 40 20 40 25 R 268 40 30 One should start observation with some initial circle reading say 25°, if we start our observation with zero circle reading our calculations for computing mean will be little bit difficult.
  10. Types of Sewers 1. Sanitary Sewer It carries sanitary sewage i.e, wastewater from municipality including domestic and industrial wastewater. 2. Storm Sewer It carries storm sewage including surface runoff and street wash. 3. Combined Sewer It carries domestic, industrial and storm sewage. 4. House Sewer It is the sewer conveying sewage from plumbing system of a building to common/municipal sewer. 5. Lateral Sewer This sewer carries discharge from house sewers. 6. Submain Sewer This sewer receives discharge from two or more laterals. 7. Main/Trunk Sewer It receives discharge from two or more submains. 8. Outfall Sewer It receives discharge from all collecting system and conveys it to point of final disposal. Types of Sewer Systems 1. Separate System If stormwater is carried separately from domestic and industrial wastewater, the system is called separate system. Separate systems are favored when: There is an immediate need for collection of sanitary sewage but not for stormwater. When sanitary sewage needs treatment but the stormwater does not. 2. Combined System It is the system in which the sewer carry both sanitary and stormwater. Combined system is favored when: Combined sewage can be disposed off without treatment. Both sanitary and stormwater need treatment. Streets are narrow and two separate sewers cannot be laid. 3. Partially Combined System If some portion of storm or surface runoff is allowed to be carried along with sanitary sewage, the system is known as partially combined system. In urban areas of developing countries, mostly partially combined system is employed.
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