How to customize transformation in Bentley map by Datum Grid method, I have two grid files and also geoid for that area. Please explain step by step
Have a look at this thread: http://communities.bentley.com/products/geospatial/desktop/f/5924/p/106540/321977#321977 and then the Coordinate System Articles, specifically the Add datum and\or ellipsoid article. Let us know if those help you.