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Sunday, 22 February 2015

Surveying Question? I forgot....

This post is not about learning or understanding something new. However, this short post is warning to my friends (or readers) who are studying architecture, civil engineers, urban planners and environmental engineer. All of you would undertake one or two short courses on GIS and surveying.

Sample survey plan from New Zealand (not related to client site)

Recently a friend of mine asked me two separate questions on surveying. First, he was asking about backsight and foresight (leveling). I have distanced away from surveying for past three years. Basically, he was asking to clarify Rise and Fall Method. I did quick internet search and mentioned to my friend there are some important principles.

Rise and Fall Method is one of the ways to transfer heights from one fixed point to multiple points. This process is called leveling. A surveyor start out at fixed permanent datum (height) and carrying the heights along a distance (of selected points). It is important procedure in construction works.

To learn more about Rise and Fall method, read here

If you read the article above, the important principles in this method are:

  • the difference between the sum of the rises and the sum of the falls, and
  • the difference between the first and the final R.L. or vice versa.
The second matter of surveying got bit complicated. My friend had to compile a survey request and scout out a suitable quotation. A feature survey for a future development site. First question I got asked is what is feature survey? Personally I was unsure what is it all about and I thought it included cadastral boundaries. I quickly checked with my professional surveyor contact what exactly is feature survey. There were three types of feature surveys (from purely locating things to complete boundary determination). He recommended to me that it is best my friend to discuss directly with a surveying firm,

I assisted my friend in writing a simple survey request for quotation which included dimensions and other engineering features to be identified. Now, my friend got some quotes and we leave it here which surveying firm will be chosen.

The points here:
  1. If you are town planner, architecture, civil engineer or environmental scientists, never, never forget what you learnt in surveying and GIS. It will haunt in your career
  2. Especially when it comes to surveying, if you are unsure about definitions, it is best to direct your client/affected friend to the surveying firm. Surveying covers legal matter and hence, as a GIS professional, you just need to exercise caution when advising.

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