reverse cord

1 1. TITLE Setting out a Reversed Curve on the Ground 2. OBJECTIVE After the field operations, the students should know the method/s of laying out a reversed curve using either the three (3) methods (Deflection, Offset from the Tangent, and Offset from the Long Chord) or combination of 2 or 3 methods on the ground. 3. MATERIALS 3.1. Theodolite/Total Station with Tripod 3.2. Steel Tape 3.3. Range Poles/Stadia Rods 3.4. Marker (Chalk) 4. PROCEDURES 4.1. Setting out a Reversed Curve on the Ground 4.1.1. Prior to the field operations, prepare the necessary survey data in setting out the reversed curve, such as: a.Length of the curves (Lc1, Lc2) b.Length of the tangent distance (T1, T2) c.Length of the long Chord (L) d.Station PC e.Station PRC f.Station PT g.Intersection angles (I1, I2) h.Radius of the curves (R1, R2) i.Degree of the curves (D1 and D2, using arc basis) j.Deflection angle k.Components of offsets from the long chord l.Possible number of full stations and plus stations m.Components of Y and X and Y’ and X’ for the backward and forward tangents, respectively. 4.1.2. During the field operation, set and level the instrument over the intersection of two (2) tangents distance T1 and take a back azimuth shot on the back tangent then measure the necessary distance from the occupied station to locate 1 st vertex. 4.1.3. Measure a tangent distance T1 from the vertex to locate and set a hub at PC.

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Transcript of reverse cord

1. TITLE Setting out a Reversed Curve on the Ground

2. OBJECTIVE

After the field operations, the students should know the method/s of laying out a reversed curve using either the three (3) methods (Deflection, Offset from the Tangent, and Offset from the Long Chord) or combination of 2 or 3 methods on the ground.

3. MATERIALS

3.1. Theodolite/Total Station with Tripod 3.2. Steel Tape 3.3. Range Poles/Stadia Rods 3.4. Marker (Chalk)

4. PROCEDURES

4.1. Setting out a Reversed Curve on the Ground

4.1.1. Prior to the field operations, prepare the necessary

survey data in setting out the reversed curve, such as: a. Length of the curves (Lc1, Lc2) b. Length of the tangent distance (T1, T2) c. Length of the long Chord (L) d. Station PC e. Station PRC f. Station PT g. Intersection angles (I1, I2) h. Radius of the curves (R1, R2) i. Degree of the curves (D1 and D2, using arc basis) j. Deflection angle k. Components of offsets from the long chord l. Possible number of full stations and plus stations m. Components of Y and X and Y’ and X’ for the backward

and forward tangents, respectively.

4.1.2. During the field operation, set and level the instrument over the intersection of two (2) tangents distance T1 and take a back azimuth shot on the back tangent then measure the necessary distance from the occupied station to locate 1st vertex.

4.1.3. Measure a tangent distance T1 from the vertex to locate and set a hub at PC.

4.1.4. Swing the instrument towards the direction of the forward

tangent and measure the distance to locate the 2nd vertex. 4.1.5. Measure the tangent distance T1 from that vertex to

locate and set out station PRC.

4.1.6. Set and level the instrument at station PC with horizontal circle reading at exactly 00°00’00” and bisect the intersection. Set the station of the first curve.

4.1.7. Set and level the instrument at station PRC and bisect

the station PC with instrument in the reverse position and sight the 2nd angle. Set stations for the second curve.

4.1.8. After marking all the points on the ground, set out the

compound curve by connecting the points smoothly using a marker. Take photographs for documentation.

5. ILLUSTRATION