Tape correction in surveying civil engineering notes. The shape of the tape will take is known as sag and can be determined mathematically. Ken snelgrove lect 7 sept 2407 slide 2 of 7 taping distance errors quanti. Pdf on zero position correction of hanging tape of gyro. If the pull at the time of measurement was 45n, find the correction per tape length. Foundation engineering books foundation engineering pdf files. Explaining kung bakit kapag too long, add and kapag too short, subtract. It is the art of measuring horizontal and vertical distances between objects, of. Take e 2 x 105 nmm2 and weigh of 1 m3 of steel as 77. Surveying traverse surveying traverse distance traverse methods of computing area a simple method that is useful for rough area estimates is a graphical method in this method, the traverse is plotted to scale on graph paper, and the number of squares inside the traverse are counted a d c b distance traverse methods of computing area a c.
Set the zerofoot end of the tape on d and the 100ft end on c. If the line is longer than the tape, an intermediate point or points must be set on line and. Refraction correction a completely eliminates curvature correction b partially eliminates curvature correction c adds to the curvature correction d has no effect on curvature correction ans. But for important and precise survey works in construction, accurate tape corrections are provided. Chapter 2 tape correction examples free download as pdf file. Measurements and errors iii8 revised may, 20 sun angles, or using a parasol to shade the instrument. Surveying is an art of determining the relative positions of various points on, above or below the surface of the earth by means of direct or indirect measurement of distance, direction and elevation. The tape correction used in surveying are as follows. Correction applied for sag when not fully supported c s w 2 l 3 24p m 2. Ct correction for temperature added or subtracted k temperature coefficient 0. Methods for measuring distances christian brothers university. This is just an example on how we teach by explaining concepts 1st. Surveying has to do with the determination of the relative spatial location of points on or near the surface of the earth.
Not correcting for these effects gives rise to systematic errors, i. If the temperature is above standard, then the tape is too long, and a measured distance will be too short. Let, p0 standard pull p pull applied in the field a crosssectional area of the tape l measured length of line. Elhallaq lecturer of surveying faculty of engineering the islamic university of gaza. The tape must be held as close to level as you can and on line while making measurements. In surveying, tape correction s refers to correcting measurements for the effect of slope angle, expansion or contraction due to temperature, and the tape s sag, which varies with the applied tension. A 30m tape is supported only at its ends and under a steady pull of 8 kg. Methods of measuring with a tape have been dealt with, although it must be said that training in the methods is best undertaken in the field. Chain surveying is the branch of surveying in which only linear measurements are made in the field.
Formulas in surveying, guide to surveying, guide to tape correction. It is the art of measuring horizontal and vertical distances between objects, of measuring angles between lines, of determining the direction of lines, and of establishing points by predetermined angular and linear. Oct 16, 2016 factors affecting the tape tape correction a. The following corrections are to be made for measurements taken with a tape because tape can never be practically used under. In surveying, tape correction s refer s to correcting measurements for the effect of slope angle, expansion or contraction due to temperature, and the tape s sag, which varies with the applied tension. A steel tape 30m long was standardized with a pull of 65n. Some natural errors such as the effect of curvature and refraction can be eliminated by a procedure. P correction due to incorrect pull applied on the tape m e modulus of elasticity of the tape material kgcm2 l length of line measured m p m pull applied to the tape during measurement kg p s standard pull applied to the tape kg a crosssectional area of the tape cm2 23 due to tension department of geodetic engineering dge. Instruments should only be checked under favorable conditions. A standard steel tape of length 30 m and crosssection 15. Pdf example problems in elementary surveying mouaz. The effects of heat waves can be minimized by surveying in cooler, cloudy periods, taking shorter measurements, or avoiding. It is one of the most important topic from competitive exam. Aug 08, 2012 this video demonstrates how to perform corrections to distance measurements.
This lecture deals with the topic tape corrections. Tape corrections in chain surveying the constructor. Zdimension height referenced to the mass spherical surface of the earth mean sea level. Staples topwinder correction tape, 10pack 51666 bic witeout ez correct correction tape, 10pack 50790 reg. The chain surveying performed by a tape is expected to have some errors due to incorrect tape measurements. It consists of a varnished strip of woven linen 12 to 16 mm wide and it is attached to a spindle in a leather case into which it is wound. From the above formula, you can deduce that the correction for a 100ft tape is about 0.
The use of levels and total stations is illustrated by a series of practical examples. Linear measurement in engineering survey, the linear horizontal distance is to be measured to complete a survey. Civil engineeringsurveying and leveling 362 important mcq pdf. The amount of correction to be applied can be determined by using the following formulas.
Ken snelgrove lect 7 sept 2407 slide 3 of 7 taping distance errors quanti. Engi 3703 surveying and geomatics topic instructor. Sag correction zif the tape cannot be supported for its length then it will hang freely under the influence of gravity. Distance accuracy is dependent on correct field procedures and often the application of corrections for various factors. This video demonstrates how to perform corrections to distance measurements. For example temperature correction for a steel tape. Chapter 2 tape correction examples slope measurement free. See offer details for bic witeout ez correct correction. In the field, make adjustments only when the instrument results are poor or require excessive manipulation. While measuring a base line at the same temperature, the pull applied was 40 kg. A survey was conducted with a 20 m chain and plan of the field was. The measurement of this linear horizontal distance between two points on the earth surface is known as linear measurement. If l is the actual or true length of the line and l is the measured length of the line then, true length of the line measured length x ll l l x ll eq.
Tape correction, sag correction and pull correction. This is suitable for the survey of small areas with simple details and an area that is fairly flat. Earth surface is considered a plane of xy dimensions. Overview of plane surveying chain, compass and plane table, objectives, principles, and classifications. A steel tape whose length varies with changes in temperature. Most engineering and property survey are plane survey correction to curvature is made for long strips e. Record distance between points by using steel tape, plumb bob and pins. L length of measured line in m p0 standard pull in newtons. Tension applied to the ends angle of slope weight of tape per unit length combined errors. Correction for standardization, correction for slope, correction of pull, correction for temperature, correction for sag, normal tension, correction for misalignment and reduction of length to mean sea level. Above this temperature, the tape elongates and provides distances that are shorter then actual. The following five corrections may be found for the measured lengths of tape.
Minor survey instruments boxsextant, planimeter, pantagraph, their working principles and uses. L, of the point a which is on the floor is 100 m and back sight reading on a is 2. Tape measured distances are limited to the length of the tape, usually 30 or 50 meters. Chapter 3 surveying equipment, measurements and errors. Apr 15, 2016 explaining kung bakit kapag too long, add and kapag too short, subtract.
This tape may be 50 or 100 ft long and graduated in feet, tenths, and halftenths. The quality of the end results, however, can only be appreciated by an understanding of the errors involved. To identify and apply taping corrections to a measurement obtained by the steel tape method. The measurement type can be divided as, direct measurement method, optical. The above expression takes care of sign of the correction also.
When the tape becomes taut, the 40ft length from c will be perpendicular to. Plane table survey principles, advantages and disadvantages, equipment, accessories and their uses. Surveying errors and adjustment a short training course prepared by. If the pull during measurement in not the same at which the tape is standardised then the correction for pull is necessary. The general formula for variation in temperature correction is as follows. Before use it is desirable to ascertain its actual length absolute length by comparing it with the standard of known length, which can be done for a small fee by the survey and standards department.
Linear measurement types, instruments and common errors. Precise measurements of distance is made by means of a steel tape 30 m or 50 m in length. Tape correction, sag correction and pull correction surveying. Correction for temperature let t0 temperature at which tape is. Large undulations in ground level can make chaining difficult.
Natural errors are mostly systematic and should be corrected or modeled in the adjustment. Surveying tapes are made of various materials and therefore can be divided into different types as follows. In ordinary chaining works, the errors are neglected. Before use it is desirable to ascertain its actual length absolute length by comparing it with the standard of known length, which can be done for. Tapes the metallic tape is a ribbon of waterproof fabric into which small brass or bronze wires are woven to prevent stretching. In surveying, tape corrections refers to correcting measurements for the effect of slope angle, expansion or contraction due to temperature, and the tapes sag. Heat waves can cause distortion in lines of sight near reflective surfaces.