Arriva Trains Wales services are set to be cancelled in a 48-hour strike as talks fail to reach an agreement.
Members of the Rail, Maritime and Transport Union (RMT) and Aslef will walk out at 00:01 GMT on Thursday until 23:59 on Friday.
Union officials accused the company of being unwilling to table an adequate pay and conditions deal.
The rail operator said negotiations are continuing - but warned passengers to make alternative travel plans.
The RMT said talks aimed at ending the dispute had "broken down without agreement".
The union accused the train company of failing "to improve working conditions and safety, and to reduce fatigue"
"RMT also wants Arriva to pay train drivers in Wales a salary which compares favourably to drivers elsewhere," said RMT general secretary Mick Cash.
The Aslef union said its executive committee met with Arriva Trains Wales (ATW) on Tuesday but also found "offers to be unacceptable".
No replacement services
On Tuesday ATW confirmed all its services in Wales and to other parts of England would be cancelled, external for the duration of the strike action, with no replacement road transport.
"We are obviously disappointed that the drivers' union has not accepted our improved pay offers and that they have opted to take industrial action even though negotiations are ongoing and progress continues to be made," added ATW director Gareth Thomas.
The train operator said its increased offer to the RMT would see drivers' base salary rise from £43,869 to £44,966, with a pledge to cut the maximum working day by an hour to 9.5 hours-a-day.
The strike will coincide with the Wales v Netherlands football international friendly at Cardiff City Stadium on Friday.
Both the train company and the unions said efforts to prevent the strike would continue.
"We continue to do all we can to avert strike action however we are advising customers to make alternative travel arrangements for these days," said an ATW official.
