The elevated extension runs north from Kasetsart University to Wat Phra Sri Mahathat with new intermediate stations at Royal Forest Department, Bang Sua and 11th Infantry Regiment.
The prime minister travelled on the inaugural service, joining the train at Ha Yaek Lat Phrao on the existing line before passing through the four new stations. The journey took 11 minutes.
Journeys on the new section are free until the end of the year. A further 14.6km extension from Wat Phrasi Mahathat to Khu Khot with seven more stations is due to open in December, taking the total length of the Sumhumvit Line to 36.3km.
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