Leveling

Leveling is a branch of surveying. Leveling is a method useful in surveying to calculate the elevation of a given point with respect to the given datum and to establish a point at a given elevation with the help of assumed datum. Using optical leveling instruments the measurement of geodetic height is calculated and level staff or rod having a numbered scale also can be designed. The Spirit level, the dumpy level, the digital level and the laser level are the common leveling instruments used in surveying.

Leveling Procedure

To arrange the leveling instrument within 100 meters or 100 yards of a known or assumed reference elevation point is the basic step of leveling procedure. A rod or staff is equipped on the point and a special feature of this instrument the instrument is that the readings can be calculated manually and automatically. Thus the height of the point above the instrument can be calculated. Next step is to hold the rod on an unknown point .After that a foresight reading is also calculated in the same method and it helps to calculate the elevation of new point. Till the destination point is reached the procedure should be sustained. It is a common procedure to execute either a complete loop back to the starting point or else close the traverse on a second point with known elevation. The closure check helps in correcting blunders in the operation and residual errors should be distributed in the most usual manner among the stations. Three crosshair instruments are also available which helps in calculating stadia measurement of foresight and back sight distance. There are two types of leveling-Single leveling and double leveling. In double-leveling, two foresights and back sights are calculated and the amount of error should be reduced by making sure that there is no difference between foresights and back sights.

Leveling instruments

Spirit leveling is supported by the instrument spirit level. Spirit level is an instrument comprising of a telescope and a tube level. The spirit level is placed on the tripod in the middle between the two points, and this method is used to find height difference between the points. A leveling staff or rod equipped with measured graduations is mounted on each point. Digital levels are leveling instruments specially equipped with scaling rods and it will be scanned to determine the height reading. Blunders in leveling can be minimized by using automation which removes the requirement for reading scale. Laser level ventures a beam which can be detected only with the help of sensor level. The sensor will be mounted and escalated on earth moving machinery, thus helping in automated reading.

Questions:

• Define leveling?
• What are the different leveling instruments?