Re: Surveying in the UK

In article <[EMAIL PROTECTED]>,
        [EMAIL PROTECTED] (Paul) writes:
> Thanks for the info guys. I have had a look around on the net and now
> have the background info on what the different datum's in use in the
> UK OSUK39 seams to be the most common. But I was able to find very
> little information on how this is ground marked and where one finds
> the coordinate values of these ground marks.
> 
> Take for example the case of a simple topo survey the first think I
> curently do is go to the local lands and survey office, search their
> records and find several coordinated ground marked positions in
> convenient locations. These then form the basis of my survey control.
> The whole survey is then in terms of Geodetic Datum 1949 and it is
> then possible to overlay boundary information or aerial mapping for
> lands and survey.
> 
> I would expect with the amount of construction work going on in the UK
> that a simlar procedure would apply but searching google and the OS
> website for information on the OSGB39 datum resulted in only
> conversions to GPS datums or background information.
> 
> Your help is appreciated.
> 
> Paul

As I said before, www.gps.gov.uk is your friend. Register yourself
so you can log in. You can then search the database of stations
for the nearest N stations to any given location in the UK. These
are all GPS surveyed stations, with ETRS89 positions down to 1mm
or better. The general assumption is that you will be using
survey-grade GPS equipment, at least to set up your own on-site
control, either using a local station as reference, or the active
station RINEX data from the same site.

ETRS89 is the chosen reference system now in the UK. However
mapping still uses the National Grid system, and lots of
historical information is referred to that. There is software
and a large database file on that site which will perform
the transformation from Transverse Mercator positions
computed from ETRS89 coordinates into National Grid
positions, and corresponding heights above the Geoid (Newlyn
height datum). Look for OSTN02 and OSGM02 on that site.

J