Public transport and schools are set to experience significant disruption as workers take part in strike action.
No bus and rail services are expected to be running on Friday during the first public transport strike in eight years in Northern Ireland.
Workers from Unite, GMB and Siptu unions started the 24-hour action at 12.01am in a dispute over pay.
The unions said the workers rejected a pay freeze – equivalent to a 11% real-terms pay cut once inflation is taken into account.
They have emphasised that strike action is “always a last resort”, but said their members have been offered no alternative.
The unions said there will be a very significant impact of the strike across Northern Ireland, and called on Secretary of State Chris Heaton-Harris to intervene in the absence of a functioning Stormont Assembly to enable workers to receive a cost of living pay increase.
Translink, which runs public transport in Northern Ireland, said there will be no train or bus services – Ulsterbus, Goldliner, Metro or Glider – operating on Friday.
The disruption includes Enterprise trains between Belfast and Dublin, with some services operating between Dublin Connolly and Dundalk only.
In a statement, Translink said it did not receive a budget for a pay offer from the Department for Infrastructure and as such cannot make a pay offer at this time.
“While we understand and recognise the concerns that have led to our trade union colleagues’ decision to vote in favour of industrial action, we have engaged with our unions and reiterated our position,” they said.
“We have urged our union colleagues not to take action which could further exacerbate the financial pressures on Translink, will disrupt services that so many of our passengers rely on, will impact on school children and could damage the livelihoods of many businesses in the retail and hospitality sectors who depend on the busy Christmas period.
“We are communicating relevant passenger information through the media, on our website, through social media, in stations, and on buses and trains. Our contact centre will also remain open 028 90 666 630.
“Translink apologises for any inconvenience this may cause.”
The Education Authority (EA) said it is expecting significant disruption to school transport in particular, as well as disruption to some school meals and cleaning services.
“The strike action will also have an impact on the availability of classroom assistants which will affect special schools in particular,” the EA said in a statement.
The chief executives of Retail NI Glyn Roberts and Hospitality Ulster Colin Neill said they were extremely disappointed, and said the action will have an impact on their sectors.
“In our meetings with the trade unions we recognised their right to strike, whilst emphasising the importance of not going beyond the one day strike this side of Christmas. We would appeal to the unions leadership to clarify this situation,” they said.
“Our members staff will face huge difficulties in getting to their place of work and likewise, our consumers will be restricted in their options to shop and socialise if bus and rail services are not available.
“Many small independent retailers and hospitality businesses are in survival mode and relaying on the Christmas trade to keep their businesses going.
“An agreed way forward on pay is needed and we need real political leadership to do that.”
A spokesperson for the Northern Ireland Office said: “The UK Government has no authority to negotiate pay in Northern Ireland.
“It is for the relevant NI departments to negotiate pay policies.
“It remains the Secretary of State’s priority to see the return of locally elected, accountable and effective devolved government, which is the best way for Northern Ireland to be governed.
“The Secretary of State has commissioned a range of information and advice from the Northern Ireland Civil Service on potential measures to raise more public revenue, or otherwise to improve the sustainability of public finances in Northern Ireland, for an incoming executive to consider.” –PA