Question

9. Outline the procedure for taping a horizontal distance over sloping ground, including how the tape is aligned, how intermediate stations are marked, and how the final length measurement is completed.

Answer 1

Answer:

There is a standard practice to hold the tape horizontal and use a plumb bob at one or both ends on an uneven or sloping ground. It is difficult to keep the plumb line steady for height above the chest. Accurate work is impossible due to wind. When a 100 meters length cannot be held horizontally without plumbing from above shoulder level, shorter distances are measured and accumulated to total a full tape length. This procedure is called breaking tape.

In measuring the distance between two points on a steep slope, rather than break tape every few meters, it may be desirable to tape along and compute the horizontal components. This requires measurement also of either the angle of inclination A or the accumulation of random errors fromm making tape ends and keeping the tape level and aligned for many short sections.

If angle A is determined the horizontal distance between point A and B can be computed from the relation.

Where, H is the horizontal distance between points.

S is the slope length separating the two points.

A is the vertical angle from the horizontal.

If the difference in elevation 'd' between the ends of the tape id measured, which is done by leveling the horizontal distance can be computed using the below expression,

  $H =\sqrt{(s^{2}- \Delta h^{2})}$

Another formula may be used to reduce slope distance to horizontal,

25 :-S=H