SRT awarded CNR Changchun Rail Vehicles (now part of CRRC Corporation) a Baht 5bn ($US 143m) contract in October 2014 to supply 115 of the stainless steel-bodied coaches, including nine first-class and 88 second-class sleeping cars, nine restaurant cars, and nine generator cars.

The vehicles are equipped with air-conditioning and retention toilets, while some of the sleeping vehicles are fitted with lifting platforms to improve access for passengers with disabilities.

The first batch of 39 vehicles was handed over to SRT on July 14 and trial runs began last month. The remaining coaches are due to be delivered by October, when the fleet will make its passenger debut on the Bangkok - Chiang Mai route.

The coaches will also be introduced on services from Bangkok to Ubon Ratchathani, Nong Khai, and Butterworth (Malaysia) next year.