Fieldwork Number 1
Fieldwork No. 01
LAYING-OUT A SIMPLE CURVE
Name : Weather :
Group No. : Place :
Designation : Time, Start :
Instructor : End :
Objectives
a. To layout a simple curve on the ground using the method of deflection when the entire curve is visible from the beginning of curve (B.C.).
II. Instruments
1 unit - Engineers transit 1 pc - Plumb bob 1 roll - string 1 pc - 50-meter tape 10 pcs - marking pins
Procedure
A. Data and Computations
1. The following data (obtained from a preliminary survey) and assumed standards will be used to layout the desired curve-centerline in the field.
Station at PI = 4 + 350 Deflection angle at PI, ( = 420 15’ (( central angle of curve) Degree of curve, D = 80 (subtending a 20 meter chord)
2. Before laying out the curve in the field, first compute the value of the following curve parameters:
Length of Tangent, T = (= R * tan ( / 2) Length of Curve, L = sum of the resulting series of chords Length of Chord, C = (= 2R *sin d / 2) Station at BC = (= station at PI – T) Station at EC = (= station at BC + L)
3. Compute the deflection angle from the tangent line ( BC – PI) to every station on the curve starting at the first full sub-station using 10-meters distance between full sub-station until station EC.
4. Tabulate the computed curve stations with their corresponding cumulative deflection angles and chord lengths between stations.
Station Deflection Angles Chord Lengths
B. Laying out the curve
1. Find a suitable place in the field and layout the a back tangent line and establish an arbitrary point of intersection (PI) along this line. 2. Locate the point of Beginning of Curve (BC), set up and level the instrument at this point designated as BC. Set the vernier to zero and
LAYING-OUT A SIMPLE CURVE
Name : Weather :
Group No. : Place :
Designation : Time, Start :
Instructor : End :
Objectives
a. To layout a simple curve on the ground using the method of deflection when the entire curve is visible from the beginning of curve (B.C.).
II. Instruments
1 unit - Engineers transit 1 pc - Plumb bob 1 roll - string 1 pc - 50-meter tape 10 pcs - marking pins
Procedure
A. Data and Computations
1. The following data (obtained from a preliminary survey) and assumed standards will be used to layout the desired curve-centerline in the field.
Station at PI = 4 + 350 Deflection angle at PI, ( = 420 15’ (( central angle of curve) Degree of curve, D = 80 (subtending a 20 meter chord)
2. Before laying out the curve in the field, first compute the value of the following curve parameters:
Length of Tangent, T = (= R * tan ( / 2) Length of Curve, L = sum of the resulting series of chords Length of Chord, C = (= 2R *sin d / 2) Station at BC = (= station at PI – T) Station at EC = (= station at BC + L)
3. Compute the deflection angle from the tangent line ( BC – PI) to every station on the curve starting at the first full sub-station using 10-meters distance between full sub-station until station EC.
4. Tabulate the computed curve stations with their corresponding cumulative deflection angles and chord lengths between stations.
Station Deflection Angles Chord Lengths
B. Laying out the curve
1. Find a suitable place in the field and layout the a back tangent line and establish an arbitrary point of intersection (PI) along this line. 2. Locate the point of Beginning of Curve (BC), set up and level the instrument at this point designated as BC. Set the vernier to zero and