The National Roads Authority (NRA) insisted today that the Dublin Port Tunnel is completely safe and that measures have been taken to address deficiencies outlined in an internal report earlier this year.
However, the body did not rule out that the tunnel may face short-term closures if any safety issues arise in the future.
Responding to a report on RTÉ's Prime Timelast night, the NRA acknowledged that an internal report had said the tunnel's 'Scada' safety system needed to be replaced.
That report was produced by Egis Tunnels, the parent company of tunnel operator Transroute, which carried out tests on the tunnel over three months earlier this year after problems with some of its computerised systems.
The operator was forced to close the tunnel on occasions to deal with technical problems, such as a communication problem between the twin-bore tunnel’s giant fans and its computer system.
Prime Timequoted from the Egis report, which said the safety system was "unsuitable to ensure the tunnel's safe operation" and that it "generates dangerous situations".
However, the NRA said today: “While this report offered the view that the existing Scada system should be replaced, all parties including Egis tunnels agreed that suitable and adequate measures could be taken and they have been.”.
“Since earlier this year appropriate measures to address various issues associated with the Dublin Port Tunnel have been actioned,” the NRA said.
A spokesman said the measures put in place included the replacement by the tunnel contractor (at his own expense) of all of the 32 pairs of jet fans in the tunnel because of “long-term durability concerns”.
The existing Scada computer servers had also been replaced, which had “dramatically improved system performance”. The NRA said there had also been improvements to the equipment maintenance procedures to achieve better performance.
Improvements also included additional monitoring of the tunnel with an “additional dedicated manned CCTV monitoring station”in the control room from 7am to 7pm.
“This is in addition to the two manned control desks in the tunnel control room, which are manned 24 hours a day,” the NRA said.
There is also additional drive-through patrolling of the tunnel by staff.
In addition, the NRA said there had been “rationalisation” of alarms in the Scada system.
“Previously the Scada system and the operators were dealing with numerous ‘alarms’ which, in reality, weren’t alarms but simply events that the system was logging. By rationalising the listing into genuine alarm cases, those alarms requiring operator notification/response are prioritised.”
The NRA said a technical group had been established to identify issues with the existing system and implement “the appropriate solutions”.
Director of Egis Tunnels Bernard Falconnat said yesterday the company was satisfied that the operator Transroute (TTO) had taken “appropriate and sufficient steps then and now to allow the tunnel to operate safely”.
“During the investigation stage and following the report, TTO implemented mitigation measures which allowed the tunnel to operate safely. In parallel, improvements to the system have been conducted,” he said.
“During this period, the tunnel has not experienced closures linked to system performance issues such as those reported earlier in the year.”
An NRA spokesman told The Irish Times: "This is a report that the NRA commissioned as a management tool to address critical issues that we acknowledged publicly needed to be addressed by both the manufacturer and installation of the system. Critical areas have been addressed.
"That does not mean we will not be closing down the tunnel in the future and we have made those decisions to do that in the past. We will not compromise safety."
Responding to the Prime Timeprogramme, Fine Gael transport spokesman Fergus O'Dowd described the leaked Egis report as "devastating" and he called upon Minister for Transport Noel Dempsey to state publicly that he is happy the tunnel is fit for use.