Thunbergia laurifolia, Laurel clock vine or Blue trumpet vine, is native to India and the Indomalaya ecozone, the species occurs from Indochina to Malaysia. It is locally known as kar tuau in Malaysia and rang jeud in Thailand.
Thunbergia grandiflora is an evergreen vine in the family Acanthaceae. It is native to China, India, Nepal, Indochina and Burma and widely naturalised elsewhere.
[Trinidad Pink Trumper Vine]
...another climber plant in Singapore Botanic Gardens, I am not sure is it same kind to Thunbergia Laurifolia?