Passengers have travelled on a train built for London's Elizabeth line for the first time.
The inaugural service went from London Liverpool Street to Shenfield, Essex, travelling on the existing TfL Rail route.
The Elizabeth line, also known as Crossrail, opens in stages from December next year.
The fleet of 66 trains have walk-through carriages, air conditioning and free wifi.
The trains will be up to 656ft (200m) long, which enables them to carry as many as 1,500 passengers.
The £14.8bn Elizabeth line project features 26 miles of tunnels and will connect Shenfield with Reading through central London, including a link with Heathrow Airport.
London Mayor Sadiq Khan said: "I'm delighted that our first state-of-the-art Elizabeth Line train has entered service on the TfL Rail service.
"The Crossrail programme remains on time and on budget, and the huge success of this project shows how vital it is for the whole of the country that we also push ahead with Crossrail 2."
London Transport Commissioner Mike Brown said: "This is an important day for rail travel and for the millions of passengers who will use the Elizabeth Line when services start in December next year."
Think-tank IPPR North recently found that £1,943 is being spent per person in London on current or planned transport projects compared with just £427 in the North.