Practical use

A typical survey project associated with a road, railway or pipeline will usually establish a control framework with GNSS. This will give coordinates in a system such as WGS84, ETRS89, ITRF, or similar.

Running these coordinates through a convertor such as SnakeGrid PointWise will put them into the required SnakeGrid system. Or this could be done directly by the software associated with the GNSS, as most major equipment systems (such as Trimble, Topcon and Leica) have the SnakeGrid algorithms programmed in.

You are now in a coordinate system that effectively has a 1:1 relationship with the ground surface. Run a traverse between control points – no need to make any kind of scale factor correction. Design railway alignments in this coordinate system – the same geometry will be set out on the ground, without a scale adjustment. Some users may not even know they’re in something called SnakeGrid coordinates – it’s just a 2D system with no scale error, a bit like a local site grid.

Other users may want to relate this system to other coordinate systems – for example to introduce land ownership data in the national coordinate system. Depending on the format of that data, it can be run through software such as SnakeGrid Transformer, which will take Bentley Microstation data and transform from one grid system to another.