Ramps vs. At Grade Connectors
Ramps are not very commonly used in Thailand. You will typically only find them where 2 roads classified as freeways meet (Federal 1-digit Highways, Motorways and Express ways).
For guidance on when to use ramps, please read here.
Naming should be done according to this article.
Most other connections involving Highways (minor/Major) are formed using At Grade Connectors