HORIZONTAL DISTANCE MEASUREMENT #2

Head tapeman

- person responsible for the accuracy and speed of

all linear measurements with the tape; person who carries out the zero

end of the tape ahead

Recorder

- keeps a record of all the measurement, sketched, and

observations taken during the process of measurements; checks to

pace of all measurements made by the tapemen for possible errors,

mistakes and blunders

Flagman

- person whose duty is to hold the range pole(or flag pole)

at selected points; help the tapeman in making measurements and

assists in clearing out obstructions along the line of sight to be

measured

Rear tapeman

- person whose duty is to assist the head tapeman

during a taping operation; one who holds the 30-m end or any

intermediate meter mark of the tape during measurement

1. Aligning the tape

2. Plumbing

3. Marking full tape length

4. Tallying tape measurements

5. Measuring fractional length

Procedure for Taping

Breaking Tape

A standard practice to hold the tape horizontally above ground and to

plumb at one of both ends when taping is on sloping on uneven terrain

surface.

Slope Taping

Made directly along the slopes when the ground is of uniform

inclination and fairly smooth, rather than break tape every few meters.

Correction in Taping

to determine an unknown length

for the purpose of laying out a required or specified length

Correction Due to Slope

When the distances are measured along the slope, the equivalent horizontal

distance may correspondingly be determined by applying an approximate slope

correction.

Pythagorean theorem.

The correction for slope is derived by using the _____

Since triangle, ABC is a right triangle.

Correction Due to Alignment

• It is usually difficult to keep the tape in perfect alignment with the end

marks when taping through grass or when a strong wind is blowing.

• Error due to alignment is generally the least important among the

different errors encountered in taping.

Correction Due to Temperature

• The tape lengthens as the temperature rises and shortens are the temperature falls.

Any change in the length of a tape due to variations

• in temperature is critical when undertaking precise measurements.

Correction Due to Tension

• During calibration, a tape is calibrated to a certain amount of standard pull

or tension on its end.

Correction Due to Tension

When used in the field during taping, it is elongated or shortened

accordingly, depending on the amount of pull applied on it.

The correction due to sag

is the difference in length between the arc formed

by the tape and the subtending chord.

Correction Due to Wind

• A strong wind blowing perpendicular to the direction of taping will move

the middle and unsupported portion of the tape to one side of the line

measured.

Combined Correction

• The correction for the effects of incorrect length of tape, temperature,

tension, slope, and sag may be combined as a single net correction per

tape length.