Systems that didn't work; professionals who didn't act. Tim O'Brienlooks at what went wrong on the N11 on Wednesday.
Wednesday's traffic jam on Dublin's M50, and tailback gridlock over much of south Dublin which led to delays of up to five hours, was astonishing not just for the scale of disruption caused but also the breadth of system failures that allowed it to take place.
What happened was spectacularly bad timing for a traffic authority that only one week earlier had been showing off its multi-million euro Intelligent Traffic Management Systems, a state-of-the-art camera-based network aimed at proving that just such a traffic jam would not happen when Dublin's Port Tunnel opens next month.
Any local authority can have a burst water main on a main road. Such an event should not, to use National Roads Authority parlance, become "a show- stopper". Work on the water main at Silverbridge near Bray, just south of where the M11 becomes the N11, mirrored work just a few yards away that was carried out over several weeks during the summer.
That had been carried out, not without major disturbance, but without the enormity of Wednesday's disturbance. On Wednesday those responsible for repairing the pipe did not put in a contra-flow system which would have used a lane of the northbound carriageway to ensure that two lanes southbound were in operation at all times.
That was mistake number one.
High on the fifth floor in Dublin City Council is the traffic centre, the heart of the supposedly cutting-edge information technology designed to manage traffic in the event of congestion. Some 150 cameras in and around the city relay live images to a wall of television screens and an amphitheatre of desk-mounted screens and operators. The M50 and M11 motorways were built with these cameras in place but also with in-the-ground loops that provide information on the number of cars in each lane, as well as their speeds.
The traffic centre also controls a range of roadside and overhead electronic signs that alert drivers to anything on the road ahead that should prompt them to modify their driving. A secondary range of temporary and mobile variable messaging systems controlled by the traffic centre is also available to be used as needed.
Motorists are also alerted by AA Roadwatch radio broadcasts. And to top it off Dublin City Council has its own studio in the traffic centre that broadcasts to motorists on 103.2FM
So how did the impression get out that there was nobody in charge on Wednesday? In theory it should have gone like this: a contra flow should have been agreed with all relevant authorities, as happened in the past.
When M11 southbound traffic started to build - as it did from about 8am on - it should have been seen, via cameras, in the Dublin City Council traffic centre and overhead or roadside messages should have warned drivers of the length of delays, giving them the option to leave the motorway at the nearest exit, as has happened in the past. Gardaí should have been asked to close access points to the motorway at Loughlinstown, diverting southbound traffic along the old N11 through Shankill and Bray or Rathmichael.
In the late afternoon and early evening, as queues stretched to Firhouse, gardaí should have been asked to close the M50 access points at Cherrywood, Leopardstown, Ballinteer, Knocklyon and Firhouse and warn drivers there was no point in joining a tailback. What happened instead was that, in the absence of a contra flow at the incident site, two motorways - the M50 and M11 - merged southbound into a single line of traffic through a road works and a single-lane bottleneck.
When the traffic centre started to broadcast on 103.2FM at 4pm, the situation was already critical. The mobile, temporary virtual messaging systems were not connected, as they are supposed to be, to the traffic centre; the nearest permanent virtual messaging system that was working was at the Firhouse junction, of no use to all who joined the motorways between there and Bray.
The in-the-ground loops are installed but do not yet report to the traffic centre, but to the National Roads Authority. Gardaí were not asked to restrict traffic joining the motorway or to advise motorists to leave the motorway and take an alternative route.
But most surprising of all is that the overhead cameras along the M50 to the M11 junction were working all the time. Those in the traffic centre must have watched the whole thing develop throughout the day and up until at least 10pm.
Where was the level of response that would give us any confidence that the other end of the M50, where the M50 meets the M1, will fare any better when the Port Tunnel opens in four weeks?