Saturday, August 14, 2021

Using Bearing and Distance to plot survey site plan in AutoCAD

 Assuming you conducted a field survey with compass or similar instrument that reads bearing to generate the following record listed below.

The table above is assumed to be the final corrected observations for our plotting. If you made a mistake in your field measurements, there are several ways to apply corrections to the measurements which is outside the scope of this article.

The site reconnaissance diagram is provided below:-

Recce (reconnaissance) diagram - source: author site inspection

Now, we want to plot this data to scale using AutoCAD. Here are the steps you need to follow:-

Step 1: Launch AutoCAD software and Setup the drawing units.

Open the units dialog box by typing "UNITS" and set the values as per your data as seen below.

Remember to check the "Clockwise" button and set "Direction" to North. This because survey bearings are measured in clockwise direction from the north pole.

Step 2: Next is to prepare and plot the data using an expression as seen in the sample output box above.

The expression is like so: @Distance<Bearing that is: @30.00<277d00'00" for the first line P1-P2.

The complete expression will look like this:-


Step 3: Pick LINE command and click anywhere on the drawing area and type the expressions above one after the other.

Alternatively, you could copy paste the entire expressions after picking line command and clicking on the drawing canvas. This will plot the entire lines on the fly.

That is it!

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