MODERN SURVEYING IMPORTANT QUESTION

 1. Conduct block contouring for a minimum area of 40 m x 40 m to draw its contour plan at a suitable contour interval.

ANS - Guide to Conduct Block Contouring for a 40m x 40m Area

1. Set Up Grid:

   • Divide the area into a 5m x 5m grid (64 points).

   • Mark points with stakes.

2. Measure Elevations:

   • Use a leveling instrument to measure elevations at each grid point relative to a benchmark (BM).

3. Choose Contour Interval:

   • Use 1m interval (e.g., 101m, 102m, 103m).

4. Interpolate Contour Lines:

   • For each grid cell, calculate where contour lines cross edges using linear interpolation.

   • Example: If elevations at corners are 101.8m and 102.3m, the 102m contour crosses 2m from the lower point.

5. Draw Contour Plan:

   • Plot grid points and elevations on graph paper or CAD software.

   • Connect interpolated points to draw smooth contour lines.

   • Label each contour with its elevation.

6. Review for Accuracy:

   • Ensure contours don’t cross and closed loops indicate hills/depressions.

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Example:

• Grid: 5m x 5m.

• Elevations: 100m to 105m.

• Contours: 101m, 102m, 103m, 104m, 105m.

This method creates a clear contour plan for construction or analysis.