SRT public relations chief Ekkarat Sri-Arayanphong said the historical Bangkok-Ayutthaya route is for Thais to be a part of the celebration and show their loyalty to His Majesty.
The SRT will operate World War II era Pacific steam locomotives No 824 and 850 manufactured by Nippon Sharyo.
The trains will depart from Bangkok’s Hua Lamphong Station at 8.10am and arrive in Ayutthaya at 10.25am.
On the way, passengers will be picked up at Samsen, Bang Sue, Bang Khen, Lak Si, Don Mueang and Rangsit stations.
The travellers can spend up to six hours in Ayutthaya before hopping back on the steam train of choice at 4.40pm and arriving at Hua Lamphong at 6.55pm.
Ekkarat said this is one of six special occasions which will see the Pacific steam locomotives brought back into service.
They would also support domestic tourism, generating revenue and employment for the local community, he added.
Tickets cost 299 baht per person and will include snacks.
Those who are interested can reserve a seat at any train station or via the D-Ticket system.
Passengers must be fully vaccinated and must present their Digital Health Pass on the Mor Prom application or a negative ATK test result taken not more than 72 hours before boarding.
The SRT will run another special steam train on August 12, from Bangkok to Chachoengsao.
Tickets will go on sale from July 13.