Up to 170,000 workers are set to go on strike for 24 hours in Northern Ireland today in a dispute over public sector pay.
Significant disruption is expected as members of the civil service, education, health and transport sectors down tools, with rallies also planned in Belfast, Derry and Omagh.
Owen Reidy, from the Irish Congress of Trade Unions, is expecting an historic turnout.
"Today's 24-hour dispute is probably unprecedented. I think it's going to be the biggest strike in the history of the Northern Ireland state.
"Today is kind of turning a page in history, where I think organized workers in Northern Ireland are saying we are no longer going to accept the situation where we're on the margins of the economy, or indeed, society."
Workers voted to strike after Northern Ireland Secretary of State Chris Heaton-Harris, refused to release funding for a pay deal, until the Stormont Assembly is restored.
Drivers and other road users are being warned to take extreme care, as the roads and footpaths have not been gritted because of the public sector strike.
Despite sub-zero temperatures gritters have only been deployed overnight on four main routes, the M1, M2, A1 and A4.
Public transport services are also all cancelled, with the exception of the Dublin to Belfast rail link which is operating a limited service between Dundalk and Dublin.
