The Workplace Relations Commission has upheld the sacking of a duty manager who "lost control" of the Dublin Port Tunnel while a junior colleague used the radio system to pull a "prank" on another colleague.

The employment tribunal heard that the tunnel operator's management considered the incident on 10 January 2018 "the most serious incident to date in terms of its severity and the potential for injury or loss of life".

The WRC official in charge of the case agreed.

In a decision published today, it rejected complaints under the Unfair Dismissals Act 1977 by the duty manager Martin Browne against his employer, Egis Road and Tunnel Operation Ireland Ltd.

The tribunal was told Mr Browne was in charge of a secure control room which monitors the Port Tunnel in Dublin and the Jack Lynch tunnel in Cork for an evening shift that Wednesday.

Ibec employer relations executive Conor O'Gorman, who appeared for the tunnel operator, said that around 6.20pm, a toll supervisor on duty in a neighbouring control room came into the room.

He took up a radio and told the people there that he was going to carry out a "prank" on one of the Port Tunnel emergency patrollers.

The tribunal was told that the patroller, identified only as "AB" in the decision, complained that he was wrongly informed that there had been a collision involving a bus in the tunnel and was asked to investigate.

"AB, as per his duties and responsibilities, drove at the highest possible speed, deploying all his vehicle warning lights, to the area where the crash was supposed to have occurred," Mr O'Gorman submitted.

He added that the false callout was made during evening rush hour traffic – and that AB would have had to make high-speed manoeuvres "in and out of traffic lanes".

"The potential for a real accident was thus greatly increased," he said.

When AB asked for the exact location, the toll supervisor replied over the radio: "You can’t miss it, there is debris all over the tunnel," Mr O'Gorman said.

AB asked again where the crash was, only to hear laughter over the radio and the toll supervisor telling him it was a "wind-up", counsel said.

"Don't pull that s**t with me!" was AB's response according to the employer’s submission.

Only then did the duty manager intervene to "chastise AB for his radio etiquette," Mr O'Gorman added.

"What about work etiquette?" AB replied.

He returned to the base and confronted the toll supervisor. He received an apology some days later, but made a formal complaint over the prank, the WRC heard.

Mr Browne, two control room staff and the toll supervisor were investigated over the incident.

The toll supervisor told the investigation that he had been involved in a "series of pranks" with AB and that AB had pranked him before, the investigating manager Jonathan Daly said in evidence.

Mr Browne told the investigation he was ill with asthma that night, "wasn’t himself" and did not become aware of the incident until he heard Mr AB swearing on the radio.

The witness added that there was CCTV footage showing Mr Browne sitting within 2.5 metres of where the toll supervisor was using the radio, and that "serious critical language" including "multi-vehicle collision involving a bus" had already been used.

Mr Browne's evidence was that AB told him it was "all sorted" after the incident and that as he took sick leave after what happened, he thought no more about it until he was called into the investigation.

Gerard Kennedy BL, who appeared for the complainant instructed by Hibernian Law, said his client had been denied due process in the investigation as he was denied copies of statements made against him and CCTV footage, which was used in the probe without his consent.

He added that his client had no opportunity to confront his accusers.

He argued that one of the workers in the control room was an "active observing participant" in the prank when he ought to have given a "stand down" order and reported to Mr Browne.

Mr Kennedy added that the none of the investigator's findings supported the finding that Mr Browne had "any knowledge" of the prank.

A disciplinary officer gave Mr Browne a final written warning – but it was upgraded on appeal to summary dismissal.

The appeals officer, tunnel director John Cleary, told the tribunal he had found that Mr Browne had "lost control of the tunnel and allowed a junior colleague to take control" for 93 seconds that evening.

He found Mr Browne had "ample opportunity to intervene", even allowing for illness or inattention.

"The nature of the radio communications and the use of key words and phrases would only have been missed by someone who knew this was a prank and deliberately chose not to intervene," he found.

Adjudicating officer Marie Flynn wrote that she did not regard the incident of 10 January 2018 as a prank, but "a foolish act which could have resulted in injury and even loss of life".

Ms Flynn found that, on balance, Mr Browne "heard the entire incident and did not take any action to stop it".

She ruled his dismissal to be a reasonable act by the employer, and dismissed the statutory complaint.