Translink said it had experienced radio communication problems which have since been fixed, but rail services are affected across the network.

BBC: Air and rail delays for commuters

All sides know that many striking rail workers have had their eyes fixed on what has been called "Black Tuesday", when many of those who have been struggling to get to work over the past week will themselves be going on strike.

BBC: RELATED BBC SITES

They answered to a Rail Regulator and his staff, who fixed internal contracts and prices, a Franchise Director and his staff who fixed fares and subsidies and a minister and his officials who tried to fix everything.

BBC: NEWS | Programmes | The Westminster Hour | Mad As Hell