GEng 111g – General Surveying I
PROFILE LEVELING
Laboratory Exercise No. 10
Name: ____________________________ Date Performed: ______________
Course and Year: ____________________ Date Submitted: ______________
I. INTRODUCTION
Profile leveling is a surveying technique employed to determine the elevation
differences along a specified line or route, commonly used in civil engineering and
construction projects. The primary objective of profile leveling is to create a detailed and
accurate representation of the terrain's vertical variations, allowing engineers and planners
to design infrastructure that accommodates changes in elevation. This method involves
establishing a series of benchmark points along the route of interest and using a leveling
instrument to measure the vertical distances between these benchmarks. The resulting
data is then presented graphically as a profile or cross-section, providing a clear
visualization of the terrain's topography and assisting in the planning and executing of
projects such as roads, pipelines, and drainage systems.
Profile leveling is crucial for ensuring the efficient and safe design of infrastructure
projects, as it helps engineers identify potential challenges related to changes in elevation.
By analyzing the profile, engineers can make informed decisions about the placement of
structures, the design of slopes, and the overall alignment of the project. Additionally,
accurate profile leveling is essential for meeting regulatory standards and ensuring the
constructed infrastructure conforms to specified elevations and gradients.
II. LEARNING OUTCOMES
At the end of this exercise, students will be able to:
• To determine the elevations of ground points along the center line of a
proposed/actual route.
• To plot the profile along the center line of the route.
III. MATERIALS AND TOOLS NEEDED
Stadia rod, automatic level, measuring tape, chalk
IV. PROCEDURE
Profile Leveling.
a) Establish stakes at every 5 meters stationed (horizontal) along the center line
of 100 m. or more (proposed).
b) Set up and level the instrument conveniently on one side of the proposed
roadway.
c) Take and record a backsight on a rod held on a nearby bench to determine the
height of the instrument.
d) Take and record intermediate foresight from as many center line points up to
within practical limits of sighting;
e) When the rod has been advanced to a point beyond which further readings to
ground points cannot be observed, establish a turning point and take a foresight
on it to determine its elevation;
f) Transfer and set up the instrument in another farther position and take a
backsight on the turning point just established. Then continue taking rod
readings on ground points as before until the end of the roadway is reached
and
g) Tabulate observed and computed values accordingly. Refer to the
accompanying sample format for the tabulation of field data.
Station BS HI FS IFS Elevation Remarks
COMPUTATIONS:
1. Computing Height of Instrument and Elevation.
The theory involved in profile leveling is the same as in differential leveling. A
backsight is taken on a benchmark or point of known elevation to determine the height
of the instrument, and the elevation of ground points is calculated by subtracting the
corresponding rod readings (foresight) from the height of the instrument.
2. Determining Differences in Elevation.
a) The difference between the sum of all backsights and the sum of all foresights
is equal to the error of closure or the difference in elevation between the initial
benchmarks and the final point.
b) The intermediate foresight reading subtracted from the height of the instrument
gives the ground elevation of a plus station.
c) The difference between the elevations of any two points obtained at the same
instrument setup equals the difference between the foresight taken on these
points.
I. SKETCH
II. RESULTS AND DISCUSSION
REMARKS, HINTS AND PRECAUTIONS:
1. Ordinarily, the interval between stakes is 100 ft, 50 ft, or 25 ft, with intervals of 100 m,
50 m, 30 m, and 10 m being utilized in the metric system. Distances are measured by
pacing or with a tape or rod according to the precision required.
2. The 100-ft points or 100-m points, reckoned from the beginning of the line, are called
full stations, and all other points are called plus stations.
3. Stationings indicate distances from the starting point. Each stake is marked with its
station. Thus, the beginning point of the survey is numbered 0+00. A stake at 1200 ft
from the beginning is numbered 12+00, and one set from the beginning of 1265 ft is
numbered 12+65. Similarly, a point 350 m from the origin is station 3+50, and a point
set 1525 meters from the origin is number 15+25.
4. The level is usually set off the center line so that sights of more uniform length can be
produced. It is usually advantageous to have the level from 15 m to 20 m from the
center line, particularly when readings must be taken on intermediate points.
5. A series of intermediate foresight readings are taken at regular intervals of 10 m to 30
m along the centerline of the roadway. and at points where sudden changes in
elevations occur, such as at the tops and bottoms of river banks, edges, and center
lines of roads and ditches. These are taken in order to give a true picture of the ground
surface along the route.
6. For a ground profile, the backsight and foresight readings are usually read to
hundredths of ft (mm), and no particular attention is paid to balancing backsight and
foresight distances. The intermediate foresight to ground points is only read to tenths
of ft (cm).
7. During profile leveling, it is usually a good practice to set a series of benchmarks
because they can be very useful later, for example, when grades are being established
for construction. These points should be set at a sufficient distance from the proposed
project center line so that they will not be disturbed or obliterated during construction.
These benchmarks may be from 10 to 20 stations apart when the differences in
elevation are moderate. Still, the vertical intervals between these benchmarks should
be about 10 m, where the differences in elevation are considerable.
8. When the profile is completed, it is necessary to check the work by running a line of
differential levels back to the beginning point or tying into another benchmark.
9. The plotted profile is generally drawn so that the vertical scale is much larger than the
horizontal scale to accentuate the elevation differences. This is called vertical
exaggeration.
10. The profile is drawn freehand since the result is a better representation of the actual
ground shape than would be the case if the points were connected by straight lines.
