- Elevation b/w two or more points some distance apart
- Requires series of set ups of the instruments
Differential Leveling
Formula
Height of Instrument = ElevBM1+BS
ElevTP1=Height of Instrument- FS
- the difference in elevation between points by employing two-level routes simultaneously
Double Rodded- Leveling
How does this differ from regular differential Leveling?
- There are two independent backsight and foresight
- 2 readings are computed separately (high and Low)
Double Rodded- Leveling Formula
Average ElevationBM= (High Points+Low Points)/2
- more precise method of differential Leveling
- three horizontal hairs are read and recorded rather than from a single horizontal hair.
Three-wire Leveling
Three-wire Leveling Formula
Stadia intercept= upper Reading (a) - lower Reading (b)
Mean of three hair reading
M=(a+b+c)/3
Horizontal distance from level rod
HD=Ks+C
Elevation of a Point =HI-(FS)
-the difference in elevation along the fixed line at designated short-measured intervals.
-designated roads
Profile Leveling
- a numerical designation is given in terms of horizontal distance at any point along a profile line away from the starting point.
Stationing
-sights are also known as ground rod readings
-taken at a regular interval at 10-30 m
Intermediate Foresight
- Mark full station are spaced at 100-m interval
- Indicate distance at any ground stake
Stationing Stakes
-difference in elevation between two points when it is difficult or impossible to keep backsight and foresight shorter or equal
Reciprocal Leveling
Reciprocal Leveling Formula`
Difference in Elevation of Two-points
DE1= (a-b)
DE2= (a’-b’)
TDE = (DE1 + DE2)/2 or [(a-b)+(a’-b’)]/2
-indirect leveling
-difference in elevation from observed vertical angles and either horizontal or inclined distances
- Limited only to horizontal distance not exceeding 300 meters.
Trigonometric Leveling
Trigonometric Leveling Formula
V= dtanα or dtanα +H.I. –RR+hcr
V= dsinα
