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Mapúa Institute of Technology

Muralla St., Intramuros, Manila.
School of Civil, Environmental, and Geological Engineering

Field Work No. 1
Laying of a Simple Curve by
Transit and Tape
(The Incremental Chord and Deflection Angle Method)

CE121F / B2

Submitted by:
Name: Patrick Emmanuel T. Gicale

Student No:

Group No: 1
Date of Performance:
Date of Submission:


And then data needed in the fieldwork is calculated first before proceeding. tangent offset method uses a measuring tape only while double-deflection method uses a theodolite or transit only. We were given a radius and an azimuth where the point of curvature is to locate. Usually.” is to be able to lay a simple curve by deflection angle. tangent offset method and double-deflection angle method. In this fieldwork. Bienvenido Cervantes Research and Discussion: The main objective of the first field work. entitled “Laying of a Simple Curve by Transit and Tape. Laying a simple curve can be done in several methods – by deflection angle method. The method assumes that there is no difference between . we lay a simple curve using theodolite and tape by incremental chord and deflection angle method. the sub-chords are provided at the beginning and end of the curve to adjust the actual length of the curve. The curve is set out by driving pegs at regular interval equal to the length of the normal chord. The fieldwork was conducted at Intramuros Walls. In the deflection angle method. Deflection angle method uses a transit and tape.Submitted to: Engr. curves are staked out by use of deflection angles turned at the point of curvature from the tangent to points along the curve.

the radius decreases. The chord definition is used primarily on railroads in civilian practice and for both roads and railroads by the military.length of the arcs and their corresponding chords of normal length or less. orienting and using the theodolite effectively.C. all the elements of the curve are inversely proportioned to the degree of curve. as in the arc definition. Conclusion: With this field work we were able to lay a simple curve by deflection angle and master the skill in leveling. As the degree of curve increases. A simple curve is a circular arc. This definition is primarily used by civilian engineers in highway construction. The underlying principle of this method is that the deflection angle to any point on the circular curve is measured by the one-half the angle subtended at the center of the circle by the arc from the P. A curve is said to be simple when it has the same radius throughout and consists of single arc of circle with two tangents meeting at actual point of intersection of roads. extending from one tangent to the next. The radius and the degree of curve are not inversely proportional even though. It should be noted that for a given intersecting angle or central angle. the larger the degree of curve the “sharper” the curve and the shorter the radius. to that point. . when using the arc definition.

the data acquired is accurate and reasonable. make sure that you are always in line of sight with the theodolite. Also. thus. There are several reasons that caused a discrepancy between the actual and experimental values for the long chord. Lastly. it is recommended that in measuring the chord make sure that the tape should not be long so that the correction in taping will be minimize. Final Data Sheet Data Given: Radius: 200m Backward Tangent Direction: N46E Forward Tangent Direction: S68E Station of the Vertex: 14+001 . it is recommended that you should follow all of the instructions written in the manual to commit less human errors and to save some time that will hinder the group to finish the experiment early. Recommendation: In order to minimize the error.It can be observed from the data gathered that the measured values are quite close to the actual length of the chord.

Station Occupi Observ ed ed PC 13+88 0 13+90 0 13+92 0 13+94 0 13+96 0 13+98 0 14+00 0 14+02 0 14+04 0 14+06 0 14+08 0 14+10 0 14+10 Increme ntal Chord Central Incremen tal Angle Deflectio n Angle from Back Tangent 8.5 32’42’30’ ’ 65’50’47’ 32’55’23 65’25’ .88 2’32’ 1’16’ 20 8’15’ 4’7’30’’ 13’58’ 6’59’ 19’41’ 9’50’30’’ 25’24’ 12’42’ 31’7’ 15’33’30’ ’ 36’50’ 18’25’ 42’33’ 21’16’30’ ’ 48’16’ 24’8’ 53’59’ 26’54’30’ ’ 54’42’ 29’51’ 20 20 20 20 20 20 20 20 20 20 1.

5 ’ 5’’ Computed length of the Chord: 217.8556m Actual Length of the Chord: 218m .1.