Snake Grid

[CharlieGreene7827]

I am working on a rail project in the UK and they are useing Snake Grid system, is there a Snake grid Coordinate system that can be added to civil 3d, or is it possible to create one

[Pointdump]

Charlie,
I've heard of Snake Grid, but I've never been able to find out anything about it. Seems to be a proprietary MicroStation Add-On that magically does something or other. I have dark thoughts about any coordinate system that can't be identified.
Dave

[CharlieGreene7827]

Its a legitimate coordinate system, created to cope with long narrow projects like road or rail that deals with any scaling or projection adjustment issues, see the link. I was just wondering if anyone new of a patch, as there dosnt seem to be anything in the country kit

http://snakegrid.org/

[Pointdump]

Charlie,
Thanks for the link. It looks like, and I may be wrong, that Snake Grid is a 500£/Year Add-On for MicroStation and FME only. I don't think it's available for Civil 3D. And since the projection parameters are proprietary, I don't think there's any way to create a custom projection in C3D.
Low Distortion Projections are common for Roadway projects like Denver's Transportation Expansion Project. TREX is a Rectified Skew Orthomorphic Projection that is included in the MAPCSLIBRARY.
Dave

[AllenJessup]

I don't think it's just an add-on or a specific coordinate system. It looks like you pay them to create a custom LDP.

http://snakegrid.org/snakegrid-for-your-project/next-step-detailed-information

It looks like there are some standard rail systems already built. Contact them and see if you can get a parameters file.

http://snakegrid.org/snakegrid-for-your-project/using-an-existing-snakegrid

I haven't been able to determine if the parameters file is proprietary or not. If it isn't. You could use the information to create a custom system in Civil 3D. Or if you're working with/for someone who need the work in a SnakeGrid. They may have the info that you could use to create the custom system.

[CharlieGreene7827]

Hi Point Dump, I have a patch for Trimble instruments, I was just wondering
if there was anyone out there who knew of a Civil 3d patch

[Pointdump]

Charlie,
"...a Civil 3d patch"
Nothing I've heard of, but then I get surprised every day. In what form is the patch for Trimble Instruments? Is it a custom coordinate system definition?
Is this for an existing project that already has a Snake Grid created? I would sure like to see the parameters of an existing project.
Dave

[CharlieGreene7827]

Dave yes this is an existing project, the snake grid was created by the
university college of London, for large long projects, like roads or
railways, if you look on the website it includes Topcon, Leica and Trimble
as partners, these are the patches that were given to me, I haven't tried
them but the surveyor who gave them to me uses Trimble, and he thought they
might help me, but as I am not using an instrument, they are of no use to
me.

I see in the list of co-ordinate systems there is one for an arbitrary
system, but I am unsure how to create one, that is why put the question out
there to see if anyone has any experience with this, there are several large
projects currently in the UK, and some recently finished, so there must be
some civil 3d user out there who has some experience of this

[AllenJessup]

The patches probably add the coordinate system to the instrument or software. Ask the Surveyor if he can get a definition out of the instrument of software.

As far as creating a system in Civil 3D. @Pointdump is knowledgeable on that.

[Pointdump]

Charlie,
Nosing around, this from SnakeGrid:
"We don’t usually give out a parameter file commissioned by others"
And even if you have the parameters you might not be able to create a custom coordinate system if you lack the necessary NTv2 file:

Dave

[CharlieGreene7827]

The problem is that it was developed with the help of Bently, who are a rival to Autodesk, though they have a list of partners, Autodesk are not on it. I am loathed to try and create one, as it could be risky and potential for error, it is not stoping me from working as every one is working on the same grid, and all the Surveyors have the corrections, as most of the instrument manufactures are o the partners list, I was just puting the question out there as there must be Civil 3d users, who have had experiance of it, and how they got arround it, as it will only be an issue with any interface with any services or infrastucture that are on the UK coordinate system, but I am sure that that can be sorted out localy

[Anonymous · Accepted solution]

hi, if you are in the HS2 project ask for the HS2TN15_NTv2.gsb file and HS2 Survey Grid NTv2 User Guide.pdf , you can crate the HS2 coordinate system in C3D.

[AllenJessup]

Honestly I'd never heard of Snake Grids before this post. We're working on an LDP. But that's County wide. Even our State DOT, who manage over 500 miles of Interstate, just use State Plane. They have a grid to ground correction for each job.

[CharlieGreene7827]

Hi Juanma77

No I am on EWR but it is part of Hs2, have made enquiries to HS2 about snake grid for AutoCAD waiting for reply, have you had experience with HS2 and snake grid, and if so does it work on AutoCAD

[Anonymous · Accepted solution]

Hi Charlie,

Yes, we are working with HS2TN15 in C3D, we change between osgb36 and hs2 the different dwg files (utilities mostly) . its possible to create hs2 snakegrid coordinate system, you will need the ntv2 file as i wrote in my previous email.

Regards

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@CharlieGreene7827 wrote:

Hi Juanma77

No I am on EWR but it is part of Hs2, have made enquiries to HS2 about snake grid for AutoCAD waiting for reply, have you had experience with HS2 and snake grid, and if so does it work on AutoCAD

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[CharlieGreene7827]

Thanks, I have already made inquiries to HS2, hopefully will hear back after the holiday, glad to hear that you are able to switch between grids

[Pointdump]

Charlie,
Please keep us in the loop when they get back to you.
Dave

[CharlieGreene7827]

Will do, it will be interesting to See how easy it is to switch between grids

[jim.turnerNX5U4]

'SnakeGrid' refers to a family of coordinate systems that are typically tailored to linear infrastructure individual projects in particular rail. These coordinate grids are virtually 'distortion free' along the line of route. 

Historically SnakeGrid coordinate systems are defined using proprietary parameter files; these are not currently compatible with Civil 3D.

However, recently a number of SnakeGrids have been converted to be fully defined using an NTv2 datum transformation coupled with Transverse Mercator projection. 

For example, the HS2 SnakeGrid is now available and fully published as EPSG code 9300: https://epsg.org/crs_9300/HS2-Survey-Grid.html 

The HS2 SnakeGrid is therefore fully compatible with Civil 3D.   There is an existing project to include the full HS2 definition within the Civil 3D coordinate system library to be available 'out of the box'.   

[paul.loge]

Hi Charlie,

I'm actually working on HS2 , on T2G section and I have same problem 1year later !😅

Did you find a solution? Did you find how to configure snake grid system on Civil 3D?

Thank you in advance!

Paul Logé

BIM senior CAD on HS2