Large Scale Land Survey Specifications

In the absence of a client specification the following is used as a basis for land survey quotations.

Datum:       

             Ordnance Survey Bench Marks where possible.

Grid:     

                Usually now based on the Ordnance Survey GPS OSTM02 National Grid and the

                OSGM02  Geoid datum.  The grid intersections would be plotted as crosses at 25m or        

                50m  intervals. If however the survey is based on a local arbitrary grid then orientation is to    

                Magnetic North.

Plotting Scale:

             To suit site - usually 1/200 or 1/500.

Presentation:

                Paper Plot, Computer Disk file in Autocad.DWG or .DXF format delivered
                on floppy disk or CD or by email.  Alternatively may be plotted on stable polyester film.

Control: 

             Survey stations would be 60mm road nails with washers in hard surfaces and 
                nails in wooden pegs otherwise unless permanent ground markers requested.
                We recommend the Feno ground anchor if the latter is required.  This control is 
                surveyed to an accuracy relevant to the plotting scale of the survey unless greater
                accuracy is requested.

Topographical Detail:

             Kerbs, walls, fences, hedges, surface changes, street furniture, services, banks,
                building footprints, positions of buildings immediately adjacent to site, trees on and
                adjacent to site to be plotted with average canopy, trunk diameter and height, 
                species will be named if possible but not guaranteed.
                Horizontal accuracy of hard detail is +/- 0.025 metres on the ground. 

Levels:  

               Spot levels taken at between 5 metre and 10 metre intervals and at changes in
                grade, cross sections of roads taken at 15 metre intervals with levels on all drainage
                covers.   Level crosses in the DTM-points layer are 3 dimensional nodes. The DTM-layer

                contains 3 dimensional ground profiling detail strings (top and bottom of banks etc)

                          

               Ridge,  parapet and eave levels of buildings on and immediately adjacent to site                   

               are  shown.     Where possible invert levels of manholes are surveyed.  Contours                   

               where relevant are plotted at 0.5m vertical interval and may be 3 dimensional.
                Vertical accuracy of levels is +/- 0.010 metres on hard surfaces and +/- 0.050
                metres otherwise. 

General:

             To assist D & H Surveys in providing our Clients with the information they      

               require we need to be  fully aware of the needs of their  Architects, Engineers and     

               Planners.  This enables us to survey the relevant detail and levels to the required 

               accuracy.   D & H Surveys are always prepared to implement  additions, alterations 

               etc. to this specification at the request of the Client.