Chaos is being chalked up on the buses for Northern Ireland's big back-to-school day next week.
The General, Municipal and Boilerworkers' union (GMB) is threatening to stage a lightning strike on the busiest school day of the year.
Next Tuesday is when most schools start back after the summer holidays, but the GMB is understood to be in dispute with the Metro/Ulsterbus parent firm Translink over drivers' duties, possible pay-offs and pay and conditions.
The union is threatening to withdraw its drivers between 7am and 9am that day, which has the potential to seriously disrupt school runs and impact massively on the morning rush hour.
The GMB is estimated to have 160 drivers employed by Translink and, and while their threatened strike action is expected to hit only Metro services in Belfast, it could affect thousands of pupils in the city.
Yesterday, when asked about the prospect of a rush hour stoppage by his members, Michael Mulholland of the GMB would only say: "We are in discussion with the company at the moment."
However, he did confirm that industrial action was an option the union was considering.
He also said that next Tuesday was one of the dates being looked at.
Any strike action being mooted will, though, involve a minority of bus drivers if talks between the GMB and Translink break down. The majority of Metro and Ulsterbus drivers belong to the Unite Union.
Unite threatened to pull its drivers off the road last March. Both Unite and the GMB balloted their members as required by law back then. But Unite is understood to have agreed a 'no redundancy' deal with Translink. Its members will not therefore join any industrial action sanctioned by the GMB this time.
Asked why Unite would not join with the GMB in any action, Mr Mulholland said: "That's a long story."
It is also understood that there is a statutory 12-week time limit between balloting workers for industrial action and actually taking it.
Said one legal source last night: "If that ballot was conducted last March the three-month deadline for the GMB is busted.
"If they still plan to go ahead with any strike action this could end up in the High Court before back-to-school day next Tuesday."
A spokesperson for Translink said: "We have received notification from the GMB union regarding their intention to carry out industrial action next Tuesday September 1.
"We are currently in communication with the GMB."