The date for when Transport for Wales' new trains will start running has now been announced.
Twelve new trains will be added to Transport for Wales' existing fleet over the next few months.
The first of these new Class 170 trains arrived at Transport for Wales' Canton depot on Sunday.
The three-car train has 186 seats and is set to be joined by a further seven three-car-units and four two-car units that each provide seating for 110 passengers.
They will run on the Cheltenham to Maesteg line from December.
Transport for Wales is also considering using the new trains on its Ebbw Vale and Heart of Wales lines.
The trains have been acquired from Greater Anglia. Training for Transport for Wales drivers will start on September 16.
Transport for Wales said the average age of its fleet will drop from 25 years to seven years by 2024.
Rolling stock director Sara Holland said: “The Class 170s provide a more modern and reliable service with air conditioning and power sockets.
"These are comfortable trains that will significantly improve capacity and provide a high standard of on-board customer experience.
“With the support of our industry partners, our fleet colleagues are working incredibly hard to introduce new rolling stock, refurbish existing trains and carry out much needed modification works.
"This is an £800 million programme that will transform the experience for our customers and colleagues alike; the average age of the fleet will drop from 25 years to seven years by 2024 and 95% of journeys will be made on a new fleet of 148 trains by 2023.”
Transport for Wales' chief executive James Price said the new trains will all be fitted with power sockets and air conditioning.
