GNSS (GPS) Surveys - EDI Surveys

GNSS control networks tied to Ordnance Survey GNSS Network, fast accurate RTK surveying. GNSS levels for flood risk assessment.

Using sophisticated survey grade GNSS equipment and utilising a network of fixed, active GNSS stations owned by the Ordnance Survey, we obtain the position of a fixed point with an accuracy of up to 10mm, an ideal tool for the provision of survey control to national grid and to Ordnance height datum.

It’s also essential for levels on sites where the Environment Agency require a flood risk assessment. For more details on how GNSS works please go to our FAQs page.

We use GNSS to:

Collect static base station observations to provide a fully adjusted network solution for large scale mapping

Establish Environment Agency Control Stations (EACS), grades E1 to E6

Carry out real-time detailed surveys based either on OS National Grid or a local grid

Provide real-time corrections from our own static reference station via radio link to 1 or more roving GNSS surveyors

Topographic Survey – The Cornhill, Ipswich

Description: Our brief was to survey the Cornhill, the current market place in Ipswich and the focal point of the town center, prior to a proposed regeneration of the area.

Survey type: Topographical survey of the square with special emphasis on the position and level of the surround building footprints.

Survey equipment: Leica reflectorless total station theodolite and Leica GNSS with Smartnet network RTK in order to provide control to Ordnance Survey national grid and level datum.

Completion time: 1 week.

Watercourse Surveys

We carry out a large number of watercourse surveys each year for the purposes of flood modelling and siltation assessment. Our main client for these projects is the Environment Agency but we also work for a number of consulting engineers and flood risk assessors. The surveys might be of anything from a dry ditch to the river Thames.

A recent project was the River Fynn here in Suffolk, a 12km long section of the watercourse from the village of Witnesham to the tidal Martlesham Creek on the river Deben. The survey requirement was to produce profiles of the watercourse at 100m intervals, profiles of all structures, a long section and digital data in ISIS and EACSD formats.

Coastal Surveying

EDI Surveys has been involved with the Environment Agency’s coastal monitoring programme since 1991 and we are currently the holders of a 5 year contract to survey profile and grid surveys on the foreshore from Grimsby to Southend-on-Sea, approximately 400km of coastline.

The majority of the work involves the survey of level profiles along fixed transect lines from low water level to a point inland of the sea defence / cliff top or dune line, with these transects being spaced at intervals between 100m and 500m.

Using RTK GNSS survey units we take recordings of the locations position, height and ground covering type (i.e. grass, mud, sand etc) every few paces. Once back in the office the collected data is processed by software to create cross sections of the coast line. When this new data is laid over cross sections of the same coast line collected from previous years we can see a graphical representation of how our coastline is changing over time. This valuable information gives the Environment Agency data to create the defence polices needed to protect us from the risk of flooding and erosion.

Equipment

Leica GNSS