Pacing 1-2 - Lecture notes 1-2 PDF

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Surveying - Pacing ...

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PACING

I.

INTRODUCTION:

Pacing provides a convenient means of obtaining approximate distances which is quite useful in surveying. It can be used to obtain a rough check on more accurate measurements made with a tape.

Rules for Accurate Pacing 1. Be systematic. Because the method is crude, it should not be rendered valueless by careless recording of paces, ignoring changes of slope and cover, or by failing to check paced

measurements

measured

distances

against at

every

opportunity.

2. On level ground adopt a pace that can be held all day. This should be your NATURAL STRIDE. Do not try to take an even three-foot step. Some people use a single-step pace instead of the two-step pace. On flat open ground, pace repeatedly over a

measured

distance

until

an

accuracy of 1/100 can be obtained.

3. Pacing in mountainous brushy terrain is not the same as pacing on flat open ground. It is not often that a normal step can be taken in the woods. Thus, one must use other procedures to help, such as estimating by eye the number of paces ahead to some recognizable point. A stick can promote more accurate pacing in brush or on steep slopes. 4. It is suggested that pacing results be regularly recorded and checked against known distances under various conditions. If possible, a pacer should check his pace every day

and preferably both morning and afternoon because of fluctuation as the day wears on.

5. A pace is a measurement of horizontal distance. Regardless of the slope, it is always in terms of horizontal distances.

This fieldwork is used to educate students on the pacing method of measuring distances in the field, as well as, determine its accuracy by comparing them to tape measurements. Pacing is a relatively easy and quick technique used to measure distances in a certain area. Pacing enables surveyors to (1) find the length of their own pace by pacing between two points with a known distance, and (2) measure the distance by pacing and then check it by taping. Nevertheless, an individual’s pace factor changes from one day to the next, and accuracy is limited.

II.

EQUIPMENT: Range poles Steel tape Markers (chalk, or crayons)

III.

PROCEDURE:

A. Determining Pace Factor. 1. Select a straight and level course of at least 90 meters apart using the tape. Designate these end points as A and B. Position the range poles behind these points as markers for correct alignment. Draw a starting line on A and an ending line at B. 2. Walk over the course at a natural pace or gait starting with either heel or toe over the starting line A and count the number of paces to reach ending line B. Make sure to keep the range pole in sight while pacing.

3. For succeeding trials, walk from B to A, then A to B, until 5 trials are completed. Record the number of paces.

4. Compute for the Pace Factor using the formula

Pace Factor =

     

B. Measuring distance by pacing 1. Define or establish the end points of another level course whose length is to be determined by pacing. Designate these end points as C and D. Position the range poles behind these points as markers for correct alignment.

2. For the first trial, walk over the course from C to D at a natural pace and record the number of paces. Then walk from D to C. Repeat the above procedure until five trials are completed.

3. Record the number of paces and compute for the paced distance using

Paced distance (m) = Pace Factor x Mean number of steps 4. Make an actual taping of the course CD to determine the taped distance.

5. Compute for the relative precision using

Relative Precision =

|  |  ...