Survey Conventions

[visard]

I'm doing an urban project and have just been handed a dozen 'surveys' for urban plots which need to be compiled. These range from simple property line descriptions, to descriptions which reference the curb line and/or neighboring land and direct me to follow wall lines from land granted by William Shippen in the 18th c. which have long ago been removed, and at least one proper surveyed plot plan. An interesting problem. I would like to have a better understanding of how our survey tools work, though, i.e. can we assume that surveyed north is a constant, are the 'Survey Bearings" given in manual, this sounds idiotic, based on a universal convention, and how are survey bearings converted to geometric angles?

Thanks for your insights.

[Chad McNeely]

Surveys vary in quality. If you need accuracy, I'm gonna guess 18th c. stuff will not be too valuable, other than as a legal reference for a new survey done by a real surveyor or civil engineer. There should be a "basis of bearings" included in each survey, otherwise who knows what the surveyor used? Older township lines and such are often skewed by a couple degrees from N-S or E-W when mapped today.

You can let VW convert survey bearings for you by entering the surveyed angle as XXdXXmXXs (preceded by N or S, followed by E or W, if you like), and once drawn VW will then display the angle as decimal degrees using geometric (x axis = 0) conventions.

[islandmon]

For a bit of background check out the the BLM >Bureau of Land Management website.

FLPMA

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