It took just one minor accident to stop traffic throughout Dublin yesterday.
A container fell off a truck at a vital crossroads - at the roundabout beside the Point depot at North Wall - at 5.50am, which turned out to be precisely the time and place to send morning commuter traffic skidding to a halt along the M1, the M50, the Port Tunnel, Pearse Street, Swords Road, North Strand, East Wall Road, in the city centre and on countless feeder routes.
Southside traffic was also affected, from Strand Road through to the East Link.
Traffic was stopped from entering the Port Tunnel, causing tailbacks miles from the scene of the incident.
A crane brought in by emergency services could not lift the container and overturned cab, so a second crane finally removed them just before noon.
By then, a straightforward accident in which no-one was injured had caused six hours of delays on roads that were already swollen with Christmas shopping traffic.
Even with the container gone, it took some time for the backed-up traffic to clear completely, said AA Roadwatch.
The city was still clogged at 1pm, when it took almost 30 minutes for a taxi to drive the 700 metres from South Great George's Street to Tara Street.
Roads throughout the city were "at a crawl" all morning said AA Roadwatch's Tressan McCambridge.
Fine Gael transport spokesman Fergus O'Dowd said the incident highlighted the fine line between the commute and chaos.
"This incident shows that Dublin traffic is still balanced on a knife edge.
"It only takes one accident or incident for the whole system to grind to a halt. It has all the hallmarks of the previous N11 incident in which work on a single water main brought the M50 to a halt.
"The fact that this happened during Operation Freeflow shows there are still gaping holes in traffic management in the city. We urgently need an emergency traffic plan to deal with one-off incidents and to ease year-round congestion.
"The fact that several massive projects are on the cards for Dublin, including two metro lines and Luas extensions, means future traffic chaos is likely, " Mr O'Dowd said.
Mr O'Dowd also called for immediate measures to prevent similar incidents.
He said a "rapid reaction force" of Garda reservists should be set up to respond immediately to provide backup and traffic management.
He suggested other measures, including extra bridges over the Liffey, more buses, a park and ride "necklace" around the M50 with public transport, and "smart" traffic lights that respond to traffic information.
Labour's transport spokesman, Tommy Broughan, said that commuters deserve better.
"It is beyond belief that a single vehicle accident occurring so early in the morning could give rise to scenes of such mayhem, for such a prolonged period and over such a widespread area."
He said reliable public transport was the only answer. In the short term, that means more bus services, he said.
"Failure on the part of the Government to adequately invest in buses under the provisions of Transport 21 will mean that the people who need to get to work will have little choice but to use their own cars.
"This will doubtless give rise to further congestion," said Mr Broughan.