GPS RTK units are a fantastic tool for collecting large volumes of level data over open areas at a reasonable price very quickly. With the development of the new Smart Net corrections service offered by the Ordnance Survey and Leica Geosystems, we can now for the first time survey in real time OS coordinates with reduced need for pre and post processing. Please see below for more information.
Site GPS control
Depending on input settings and satellite availability our GPS surveying equipment can achieve detailed accuracy in the region of +/-20mm. By setting up on a fixed point for a longer period, we can observe the satellites as they complete their orbit overhead, apply complex corrections and achieve even greater degree of precision.
We use our GPS systems as a conventional surveying tool, measuring in the same way we would survey using a robotics total station. GPS offers the advantage of not requiring a line of sight between two points. This allows us to set up and move, cover miles in one day, returning to the car at the end with excellent coordinate data of our site. We have recently surveyed a 32km square island for the RSPB, solely using a Smart Rover GPS receiver. A receiver was also mounted on our adapted quad bike to gather detailed level information over cultivated fields.
GPS datum levelling
A major application of GPS is the instant production of levels to be inserted into your Flood Risk Assessments (FRA’s) to be submitted to the Environment Agency as part of the planning process. We can overlay the levels onto existing Ordnance Survey mapping, add contours and show the site in relation to the local flood zones as supplied by the Environment Agency. Route of safe access and egress can be explored a requirement of your FRA application in accordance with government planning policy statement 25.
GPS grid positioning
Typically GPS data is translated from latitude and longitudinal bearings (ETRS89 or WGS84 coordinate systems) to Great Britain’s national mapping grid (by the Ordnance Survey), eastings and northings or to an existing local reference frame.
By positioning our surveys to OS grid we are able to easily compare our plans to existing mapping. This can be useful, for example; to resolve boundary disputes, establish and set out the position of historical and industrial features now no longer visible on the ground. Alternatively to show areas of encroachment over time from neighbouring properties and update OS plans with new information.
In addition to GPS surveying, if number of satellites available is restricted by obstructions we are always able to supplement information with a total station.
For more details on our GPS surveying or utility surveys and more get in touch with us today.