The strike will affect Ulsterbus and Citybus services

After four hours of legal argument on Thursday, Justice Girvan ruled against Translink, who were seeking an injunction to block the strike on Friday.

Lawyers for Translink had argued that since workers have been balloted about action, there had been improved offers which were not referred back to them.

Ciaran Rogan, of Translink, said the company was disappointed but that it would not appeal.

"We felt really we had a duty to pursue every avenue to attempt to avert the action given that so many people will be let down," he said.

"Strike action is completely unnecessary.

It shows the side of Translink that is willing to go to court rather than have meaningful negotiations with the unions trying to solve the money problems that all drivers have John Coffey Transport and General Workers Union

"The offer on the table is fair and reasonable and there are no further negotiations planned.

However, union representative John Coffey said the case was about the democratic right to strike.

"It shows the side of Translink that is willing to go to court rather than have meaningful negotiations with the unions trying to solve the money problems that all drivers have," he said.

Bus drivers' unions say the strike, which will start at midnight on Thursday, will be the first of a series of one-day stoppages over pay and conditions.

Friday's strike, which will see all Citybus and Ulsterbus services off the road, will affect 180,000 people, including 65,000 school children.

Schools have been told they can close if they think pupils' safety would be affected, while the Department of Education has said it would not count student absences.

A senior teacher has warned that if the threat of more strikes is carried out they could be disastrous for children sitting the 11-plus exam next month.

Talks between union representatives and Translink management on Wednesday failed to resolve the issue.

'Devastating effect'

The unions said the other strike dates would be on 24 and 31 October and 7 and 10 November.

The drivers' unions said it was not happy with the current offer on the table because their members' wages are so low.

Drivers' basic salaries are about £13,500 which they supplement with overtime of about £5,000 a year.

However, a new European directive will limit overtime hours so unions want to significantly raise the level of basic pay.

Mr Coffey said the increase on offer - 5.7% - was not enough.

Dr Desmond Hamilton, director of the National Association of Head Teachers, said the strike could have a "devastating effect" on children sitting their 11-plus examinations next month.

"The nature of this exam is that all children are involved at the same time throughout Northern Ireland," said Dr Hamilton, who is also principal of Strandtown Primary School in east Belfast.

"At this stage, if there was even a suggestion of this level of disruption on the 7th or 21st November, an alternative would have to be set."

A statement issued by Translink on Wednesday said the unions had rejected a "specific request" that school services be exempt from the planned industrial action.

"We carry 65,000 children to and from school every day and it is disappointing that they are being let down at this critical time of the year," said Translink's Director of Operations Philip O'Neill.

This would have a devastating effect on all schools right across Northern Ireland Dr Desmond Hamilton National Association of Headteachers

"I would appeal to all bus drivers to turn up for work this Friday as normal, in spite of the planned strike.

"Those who turn up will provide school services as a priority."

Alan Walker from the General Consumer Council said many bus users were elderly or on low incomes.

"One in three homes here doesn't have access to a car, so those people are completely dependent on public transport to give them some sense of a normal daily life," he said.

Translink said no railway services would be affected by the industrial action, but bus tickets could not be used on trains.

Bus lanes will be open to regular traffic during the strike.

Regional Development Minister John Spellar said his department had discussed the matter with the police.