what is the use of "non-tangential alignment " option in the startup window of mx road
Pretty much what is says. Horizontal elements on an alignment normally have to be tangential. However a non-tangential alignment allows for a bearing discontinuity between elements. Useful for footway ramps, where you might have only have straight elements, with no curves.
It was introduced quite a while ago now. the geometry bit was always relatively easy it was how the design and interface options dealt with the resulting connections. There are some limitations in the design processes, I think you have to use a triangulation model to interface too, and I think there are decisions you need to make for the design.
Its been in vertical for even longer. Theres a fix to fix option in the Specials I think.
Simon Pegg
Bentley Civil Support