A system control failure threw Hua Lamphong, the country's main railway station into chaos Wednesday morning, while two unrelated train accidents later followed in the provinces.
A power failure disabled the track control system, blocking all arrivals and departures of trains from about 6am onwards.
By the time technicians overrode the computerised system and manually operated the track switches, more than 10 trains had been affected with hundreds of passengers suffering delays lasting some two hours, according to Phonsutthi Thongsat, the State Railway of Thailand's train operation centre director.
Incoming trains, including those from the provinces, lined up outside the station until the repairs were finished about 8am and services resumed.
Only minutes later, a goods train jumped the track in Den Chai district of Phrae in an unrelated accident. The train was sent from Sila At station in neighbouring Uttaradit and was destined for Long, another district in Phrae.
As the train was negotiating a bend in tambon Sai Yoi, it ran into track repair equipment and the locomotive left the rails. No one was injured.
It happened near the spot where the long-haul Nakhon Phing train bound for Chiang Mai had an accident in July.
The accident caused the suspension of some northern train services, which were expected to resume in the evening.
Transport Minister Chadchart Sittipunt said an inquiry is under way.
Also Wednesday, a train rammed into an 18-wheel container truck at a railroad crossing, killing a railway official and injuring a passenger in the truck and a motorcyclist in Chon Buri's Phan Thong district.
The dead official was Sombat Wichitkun, who operated the barricade. The injured were Praprut Kongthon, the truck's mechanic, and an unidentified 18-year-old woman who was driving a motorcycle behind the vehicle.
Witnesses said the truck tried to cross the track as the train was approaching.
The train crashed into the truck and crushed Sombat. The truck driver fled the scene.