Warsaw deputy mayor Renata Kaznowska said that the contract, which is valued at €72.4 million, is the largest purchase in SKM's history.
Further details for the next franchise and the South West Metro will be shared "at the earliest possible opportunity" following the standstill period.
At 07:00 on Saturday May 19, the first Brightline train service will depart West Palm Beach for Miami Central station.
In total, RegioJet has an order for 10 Traxx locomotives with Bombardier.
The 14-month programme will cost $4 million and will see the flagship service's 20 trainsets refurbished ahead of the introduction of the 28 'next generation' Alstom trainsets in 2021.
On June 24, Virgin Trains East Coast's contract will end and the Department for Transport-owned operating company, London North Eastern Railway, will take over the running of services.
Swedish train operator SJ has announced plans to refurbish its sleeper carriages and overhaul its booking system following a surge in demand for the long-distance services.
The joint venture - 70 per cent First Group, 30 per cent Trenitalia - has pulled out to focus on its bid for the West Coast Partnership franchise, according to a spokesperson.
The locomotives arrived over the weekend of April 14-15 after being assembled and tested by Bombardier at its Kassel plant, Germany.
The Macau SAR Government has awarded MTR a MOP 5.88 billion (€588.8 million) operations and maintenance assistance services (O&M) contract for the Macau Light Rapid Transit (LRT) Taipa Line.