ELEMENTARY SURVERING
FIELD MANUAL
COURSE AND SECTION: CE 120-0F / B1
SUBMITTED BY:
SN. 14 NAME: Dizon, Joshua Dominic C. STUDENT NO.: 2013150714
GROUP NO. 2 CHIEF OF PARTY: De Guzman, Raphael
DATE OF FIELD WORK: 07/28/2015 DATE OF SUBMISSION:08/06/2015
SUBMITTED TO:
PROFESSOR: Engr. Bienvenido Cervantes
FIELD WORK NO. 6
DIFFERENTIAL LEVELING WITH
TURNING POINTS (DOUBLE RODDED)
FINAL DATA SHEET
FIELD WORK 6 DIFFERENTIAL LEVELING WITH TURNING POINTS (DOUBLE RODDED)
DATE: July 28, 2015 GROUP NO.2
TIME: 12:00-4:30PM LOCATION: Intramuros WEATHER: SUNNY PROFESSOR: Engr. B. Cervantes
STATION BS HI FS ELEVATION BM1 1.48 151.48 - 150 10L 1.48.48 151151.515 1.445 150.035 10R 1.48 151.485 1.475 150.005 20L 1.52 151.49 1.545 149.97 20R 1.555 153.055 1.54 149.945 30L 1.485 153.055 1.54 149.945 30R 1.545 153.34 1.26 151.795 40L 1.565 151.6 1.46 150.035 40R 1.345 153.285 1.40 151.94 50L 1.51 151.59 1.52 150.08 50R 1.445 153.16 1.57 151.715 60L 1.445 151.560 1.485 150.105 60R 1.505 153.15 1.515 151.645 70L 1.465 151.52 1.505 150.055 70R 1.48 153.12 1.51 151.64 80L 1.50 151.52 1.5 150.02 80R 1.49 153.105 1.505 151.615 90L 1.505 151.54 1.485 150.035 1.495 1.495 153.11 1.49 151.615 100L 1.48 151.495 1.525 150.015 100R 1.51 153.155 1.465 151.645 BM1 - 151.48 2.185 150.97
Objectives:
1. To develop the skills in determining the difference in elevation two
points without the need of returning the circuit to the original point
of reference by using two observation points every time BS and FS
are taken.
2. To master the art of using the precise level during fieldwork.
3. To acquire the confidence of working with one’s party or group and
to be fully responsible in the performance of the assigned task.
Instruments:
1. Precise level
2. 1 levelling rod
3. Chalk
4. Plumb bob
Discussion:
This field work was about differential leveling with turning points
(double rodded) where we measured 100 meters and marked every 5
meters of it. We should determine the difference in elevation between two
points which are accessible from a single point of observation.
To begin with the field work, first, we borrowed the instruments
needed for the said field work. After borrowing the instruments we went to
Intramuros walls near Mapua. We then start measuring 100 meters in a
straight road using only our pace factor as the way to measure. We marked
every 5 meters of the entire 100 meters which will be used as stations for
the field work. We set the height of our instrument and then place it away
from the station. We used two station for the instrument, one measuring
from 0-50 meters and the other measuring from 50-100 meters. The
instrument must be parallel with the ground so we must adjust the legs of
the tripod and also set the bubble in the instrument at the center. Take note
that we used one leveling rod alternately at every station and position it
atleast 2 meters from the point (left and right). The procedure was repeated
until we reached the 100 meter mark then data are recorded. After
gathering all the data needed and performing the field work properly we
can now complete the field work and do our field report.
Conclusion:
Though we find it difficult on how to figure out this fileld work, we find
ways on how to do this because our group was determined to complete this
field work no matter what so that we could have results to compute for our
field report.
We acquire the knowledge on how to find the elevation of a point
from a benchmark of known elevation by establishing turning points and
from the points that are unkown elevation. We also develop the technical
circumstances on how to use the precise level, first we need to adjust the
leg of the tripod then we found out on how to make the bubble of the
precise level in the middle of the circle then we start the field work. We are
also determined on how we can work harmoniously and effectively as a
group while performing each assigned task to us.
I can now conclude that with the help and cooperation of each other
in our group, it encourages us to perform all the task perfectly. We are able
to determine the elevation in the field to locate points at specific elevations.
And that of the leveling ground, there would not always be a constant
elevation in every point. Therefore, in order to measure the different
elevations, we will be doing a type of leveling called differential leveling,
where the ground is measured from its back and front sights, and is used to
get the correct elevation and height of the instrument.
Research:
Differential Leveling Survey Specifications
Survey specifications describe the methods and procedures needed to attain a desired survey standard. Specifications in this section are based on Federal Geodetic Control Subcommittee (FGCS) standards and specifications. Except where noted, they have been modified to give results that will meet the requirements for various types of differential leveling surveys typically performed by the Department. For details regarding standards, refer to Chapter 5, “Accuracy Classifications and Standards.”
The Department’s differential leveling survey specifications shall be used for all Caltrans-involved transportation improvement projects, including special-funded projects.
Differential Leveling Method
These specifications apply to the use of compensator-type engineer’s levels and electronic digital/bar code leveling systems. Specifications for trigonometric leveling are covered in Chapter 7, “Total Station Survey System (TSSS) Survey Specifications.” Specifications for GPS derived elevations are covered in Chapter 6, “Global Positioning System (GPS) Survey Specifications.”
Equipment to be used is specified under “Method” for each order of accuracy in this Chapter.All differential leveling equipment must be properly maintained and regularly checked for accuracy. Systematic errors due to poorly maintained equipment must be eliminated to ensure valid survey adjustments. Equipment acquisition, repair, adjustment, and maintenance is covered in Chapter 3, “Survey Equipment.”
General Differential Leveling Survey Specifications Sight Distances
Sight distances and the balance between foresights and backsights are critical to maintaining accuracy in differential leveling. Sight distances should be reduced when poor environmental conditions are encountered. Under normal conditions the specified
sight distances in this Chapter will produce surveys that meet the Department’s accuracy standards for second-order, third-order, and general-order surveys. See Section 8.3-3, “Limits of Sight Distances”.
Turning Points
Turning points (TP) should be set in stable, protected locations. Spikes or large nails set in pavement; wooden stakes set in firm soil; prominent points such as rock outcroppings or the top of concrete curbs may be used as turning points. Each turning point should have a definite high point or be marked at the exact point of rod contact. If a permanent TP cannot be driven, then a turning plate (“trivet” or “turtle”) weighing at least 15lbs. should be used. In situations allowing neither turning pins nor turning plates (sandy or marshy soils), a long wooden stake with double-headed nail should be driven to a firm depth.
Turning points (except turning plates) should not be removed after use, but left in place to provide a check in the event of blunders or excessive misclosures. A solid, well defined turning point may be used as a temporary benchmark (TBM).
Benchmarks
Establish benchmarks with physical characteristics and quality commensurate with the order of the leveling survey. Benchmarks should be of a stable, permanent nature; e.g., galvanized steel pipe; steel rod driven into a firm soil base; or cast in place concrete. A brass disk epoxied into a drilled hole in rock or concrete is also acceptable.
Benchmarks should be conveniently located and easily accessible. Whenever possible, benchmarks should be located outside of construction areas, clear of traffic, and within a public right of way or easement. Allow for future changes in landscaping and overgrowth of trees and foliage.
Space benchmarks as required by project conditions and convenience of operation, generally not to exceed 2600 feet apart. Minimum spacing for benchmarks is normally 1000 feet. Prepare a written benchmark/station description for inclusion in the survey notes and in the project final control report.
Differential Leveling Survey Notes
Rod readings for single- or three-wire leveling operations using a compensator-type engineer’s level, should be recorded in digital form on a hand-held programmable calculator, computer or data collector. Such calculators must produce a hard copy of all readings, reductions, and adjustments. Hard copies of data collection, reduction, and adjustment calculations will be incorporated into, and become a permanent part of the survey field notes. See Chapter 14, “Survey Records.” Field notes can be recorded by hand in a bound field book, or on the Department’s forms HCS-88 or DH-SP-14.
Adjustment of Differential Leveling Surveys
Second-order and third-order differential leveling surveys, when run as a single loop or section, are adjusted by a straight-line interpolation process. Corrections for the closing error will be prorated to each benchmark and TP between the two controlling benchmarks.
When multiple leveling survey loops interconnect to form a network, such as in corridor or project control, points common to two or more loops will be adjusted by application of least-squares adjustment. See Section 5.4 “Least Squares Adjustment.”
