Introduction

The purpose of this surveying activity is to introduce our group about circular curve.We have included the following data,autocad draw and calculation.In the geometric design of motorways, railways and pipelines, the design and setting out of curves is an important aspect of an engineer’s work.That was importance to use to know the curve some place before constructing a road,tunnel or pipeline.

Objective

1. To know the usage of the equipment for finding the curve.2. To find a value of subtangent from starting point to PI.3. To determine the length of curve at the site from point to .

Apparatus

1. Electroninc Distance Measurement (EDM)

2. Prism

3. 2 of Tripod

4. Hammer

5. 7 of Picket

6. 5 of Arrow

7. Measuring Tape

Theory

Horizontal, circular or simple curves are curves of constant radius required to connect two straights set out on the ground. Such curves are required for roads, railways, kerb lines, pipe lines and may be set out in several ways, depending on their length and radius. Figure 4.1 illustrates how two tangents are joined by a circular curve and shows some related circular curve terminology. The point at which the alignment changes from straight to circular is known as the BC (beginning of curve).The BC is located at a distance T (sub tangent) from PI (Point of tangent intersection).

The length of a circular curve (L) is dependent on the central angle (∆) and the value of R (radius). The tangent deflection angle (∆) is equal to the curve’s central angle (Figure 4.2). The point at which the alignment changes from circular back to tangent is known as the EC (end of curve). Since the curve is symmetrical about the PI, the EC is also located at distance T from the PI. From a study of geometry, we recall that the radius of a circle is perpendicular to the tangent at the point of tangency. Therefore, the radius is perpendicular to the back tangent at the BC and to the forward tangent at the EC. The terms BC and

EC are also referred to by some agencies as PC (point of curve) and PT (point of tangency) and by others as TC(tangent to curve) and CT(curve to tangent)

Figure 4.1 Circular Curve Terminologies(Source: Surveying With Construction Application, B.F. Kavanagh)

Table

R = 600m

Chainage = 461.34m

Point Chainage Chord (C) Change Deflection Angle ( )

348.54 0 0 0A 360.00( ) 11.46 11.46 01’43”B 380.00( ) 20.00 31.46 12’55”C 400.00( ) 20.00 51.46 34’35”D 420.00( ) 20.00 71.46 1°06’41”

421.67 1.67 73.13 1°19’50”

Calculation

To find the value of subtangent,

=

To find the value of length of curve,

Procedure

1. Calculate the setting out data of curve by angle and distance method from the data provided.

2. Observation of the area.3. Mark the intersection point IP and use EDM to set the angle of intersection to

determine the point and .4. Transfer the EDM to point .5. Open the first deflection angle ( ) and determined the distance according

to the Table.Mark point A with the arrow.6. Open the deflection angle ( ) and determined the distance .Mark the

point B with arrow.7. Repeat step 6 until work up to the point last.

Result

A curve line on a standing men from no. 1 until no. 6.

Discussion

1. The usage of Curve in surveying ?

The design and setting out of curves is an important aspect of an engineer’s work. The initial design is usually based on a series of straight sections whose positions are defined largely by the topography of the area. The intersections of pairs of straights are then connected by horizontal curves. In the vertical design, intersecting gradients are connected by curves in the vertical plane.

Conclusion

This report introduced usage of Circular Curve on site.We present information about the curve and apparatus that use on the site.We also provide a picture and autocad draw to make it more easier to understand about this surveying activity.Understand about usage of formula for finding distance from to and distance from to PI.We also can see the curve in the end of surveying activity with a same distance that we calculation earlier.

Attachment

1. Setup EDM

2. Setup Prism

3. Measuring

4. Measuring a distance for putting an arrow

CURVE

OFFSET BY TANGEN