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FIELD WORK #2: LAYING OUT COMPOUND CURVE
I. OBJECTIVE: The student should be able to lay out a reverse curve through location of points on
the curve by chord distance-deflection angle method.
II. ILOS:1. To be able to compute for the other elements of the curve using the given
elements. 2. To be able to lay-out the curve.
III. INSTRUMENTS: 1 - Total Station2 – prism - Chalk
IV. PROCEDURE:1. Set/level total station on the field convenient enough to lay out a reverse curve.
Set as station PRC. (0 + 50)
2. Before laying out the curve, make sure that all the necessary elements of the curve is calculated using the given data.
3. Start laying out the first simple curve. Using the calculated length of curve, interpolate stations with distance of 5m on the curve between sta PRC to the other
point of the curve (sta PT).
4. Repeat until all stations between PRC and PT is obtained.
5. Lay-out the second curve on the other side of station PRC. Start by sighting a point on the tangent line of the first curve adjacent to sta PRC. Then rotate the total station 180° to locate the PI of the second curve using the calculated tangent distance. Mark the point.
6. Using the total station, sight station PT, again rotate the total station 180° to lay out the length of long chord of the second curve. Mark the point and set as sta PC.
7. Calculate the deflection angle from the second tangent line to the interpolated stations to lay-out the second curve.
8. Tabulate the data.
V. TABLE:
For first curve:
Stations Points Central Angles
Deflection Angles
Chord Length
0+45 A1 13°3’ 6°31’30’’ 4.98m0+40 A2 26°6’ 13°3’ 9.913m0+35 A3 39°9’ 19°34’30’’ 14.708m0+30 A4 52°12’36” 26°6’18’’ 19.317m0+25 A5 65°15’36” 32°37’48’’ 23.671m0+20 A6 78°18’36” 39°9’18’’ 27.719m
0+16.69 PC 86°47’24” 43°23’42’’ 30.205m
For second curve:
Stations Points Central Angles
Deflection Angles
Chord Length
0+55 B1 19°40’32.69” 9°50’16.35’’ 4.975m0+60 B2 39°21’5.39” 19°40’32.7’’ 9.804m0+65 B3 59°1’38.08” 29°30’49.04’’ 14.344m0+70 B4 78°42’10.78” 39°21’5.39’’ 18.460m
0+72.055 PT 86°47’24” 43°23’42’’ 20.03m
VI. COMPUTATION:
VII. SKETCH
R1 R1
R2
R2
t1
t2
t2
t1PT
PC
PRC
I1
P
I2
A
B
D
VIII. DOCUMENTATION
Setting up the total station at PRC
Levelling the total station
Laying out the length of long chord of the first curve
Locating the Middle Ordinate of the first curve
Laying-out the first curve
Locating the PT of the second curve
Locating the middle ordinate of the second curve
Laying out the second curve