4 : Leveling Methods

Question 1

a method of determining differences in elevation between points by employing two level routes simultaneously

Answer 1

Double-Rodded Differential Leveling

Question 2

a more precise method of differential leveling wherein three horizontal hairs (or threads) are read and recorded rather than a single horizontal hair

Answer 2

Three-Wire Leveling

Question 2

• process of determining the difference in elevation along a fixed line at designated short measured intervals
• It is executed to provide data from which a vertical section of the ground surface can be plotted

Answer 2

Profile Leveling

Question 3

based on the principle that two consecutive readings from the same instrument position gives the difference in elevation of the two points sighted

Answer 3

Rise and Fall Method of Leveling

Question 4

• Used to determine the difference in elevation between two points when it is difficult or impossible to keep backsights and foresights short and equal
• These conditions usually exists when running a line of levels across wide rivers, lakes, or in rugged terrain where deep canyons and ravines are encountered

Answer 4

Reciprocal Leveling

Question 5

• The process of determining the different elevation of station from observed vertical angle and known distance
• The vertical angle are measured by means of theodolite.
• The horizontal distance may either measured or computed.
• Relative heights are calculated using trigonometric formula.

Answer 5

Trigonometric Leveling

Question 6

• ideal in determining large differences in elevation in rough or mountainous terrain where extensive areas need to be covered
• results are better obtained when the weather is stable and climatic conditions are constant
• such surveys are best undertaken at about mid morning or mid-afternoon (readings at about noon time, early in the morning, or late in the afternoon should be avoided)

Answer 6

Barometric Leveling

Question 7

• done to determine the elevation of a point located
  higher than the telescope of the instrument
• in this situation, the rod is held upside down and its
  base is placed up at the desired point

Answer 7

Inverse Leveling

Question 8

• a type of cross-section required for most route projects such as roads and railroads
• planimeter – used in determining the cross section areas

Answer 8

Roadway Cross-Sections

Question 9

• Employed in the construction of structures and buildings, and the excavation of borrow pits
• borrow pit – an open area which is usually adjacent to a construction project where suitable fill material is excavated

Answer 9

Borrow-Pit Cross-Sections