The city of Ottawa has provided Grid shift files for conversion from NAD83 Org to NAD 83 CSRS v6

Could these be added to the default Bentley install

Other Info:

General Info:

• New topo surveys and mapping carried out by the City will be in NAD83 CSRS and Canadian Geodetic Vertical Datum (CGVD)2013 from 2024 onwards.

• The shift in Ottawa between NAD83 Original and NAD83 CSRS is approximately 0.3 m horizontal and 0.3 m vertical.

• Most City projects will be in NAD83 CSRS this year. Depending on the project they may decide that some City projects starting in 2024 will still be carried out in NAD83 Original. Depends on the mapping information available and other factors. But the expectation is that all new City projects will use NAD83 CSRS starting in 2025.

City Translator Files

• A consultant has helped the City develop the geodetic transformation (.gsb) files attached to assist with converting drawings from NAD83 Original to NAD83 CSRS and vice versa.

• My understanding is that for now these files are for use on the Bentley platform only but the City is working on Autodesk versions.

• These .gsb files have been developed specifically for use within the City of Ottawa geographical area as they are based on established control points across the City and are more accurate than the similar Federal .gsb files which are available. They are not for use outside of the City’s limits.

• It’s important to note that the .gsb files provide a 2D conversion only, so only shifts horizontally. Any vertical information in the source drawing will need to be adjusted by 0.3 m separately to account for the difference in vertical datum.

• The City states that the Ottawa .gsb files will convert to an accuracy of 5 cm or less.