Aucklanders wondering when they will become inhabitants of "the world's most liveable city" have suffered a triple-serving of key service meltdowns in one week.

Chaotic scenes at the Britomart and Newmarket railway stations in Thursday morning's commuter rush followed up to 12 hours without connections for about 15,000 internet users on Tuesday night, and huge traffic jams through much of the central city and beyond after a crash on the harbour bridge last Saturday.

The Electricity Commission is still investigating - under ministerial instructions - the cause of a cable fire which cut power to 85,000 Auckland households and businesses in October, for up to two days in many cases.

Auckland Mayor Len Brown, whose oft-stated goal is to make Auckland the world's most liveable city, has had little to say about the latest setbacks.

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On Monday, he was leaving it to the police and the Transport Agency to investigate why it took three hours to reopen three of the harbour bridge's northbound traffic lines after a crash between two motorbikes and a truck, causing traffic jams along many kilometres of roads.

"Given the seriousness of the crash and its impact, the mayor is hopeful reviews of the incident by the police and NZTA [the agency] will indicate areas where there might be room for improvement in the future," a spokesman said.

Results of a special "debrief" on the pile-up held yesterday between those two organisations and others such as Auckland Transport have yet to be revealed.

After the week's second transport debacle, in which about 3000 commuters had their trips to the city disrupted by a broken train outside the Britomart tunnel on Thursday, the mayor blamed "decades of neglect" of the city's infrastructure.

"We risk repeats of this morning's delays until the day the [$2.4 billion] City Rail Link is built and Britomart stops being a dead end," Mr Brown said in a brief statement, issued by his office in the absence of his availability for an interview.

Auckland Transport says 15 trains were disrupted, many of which unloaded passengers at Newmarket Station so they could transfer to buses, after an emergency brake on a new electric train was erroneously triggered outside Britomart.

It took about 45 minutes to shunt the train into Britomart, and about another hour for services to return to normal.

One commuter described it as a "passenger transport version of Saturday's harbour bridge gridlock."

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Public Transport Users' Association coodinator Jon Reeves shares Mr Brown's view in citing the blockage as a classic example of why Britomart needs to be turned into a through station, removing delays for trains waiting for others to back out or clear tracks leading to it.

"Because we don't have the City Rail Link we have no resilience, and at peak times thousands of commuters are being affected," he said.

"It should be a wake-up call for the Government, it needs to invest and get the CRL underway."

But Auckland Council infrastructure chairman Mike Lee believes both the harbour bridge and rail disruptions point to short-comings in the management of transport networks as well as their physical fragility.

"There seems to be a certain fragility - not just the lack of resilience of the network - it's also the standard of decision-making," he said.

An Auckland Transport spokesman said the stricken train could not have been shunted to a station upgraded off The Strand in Parnell for $1.7 million for emergency use during the 2011 Rugby World Cup, as it was full of other rail rolling stock on Thursday.

But Mr Lee called for better contingency planning, saying one disabled train "it shouldn't bring the whole network to a close."

• Early October - 85,000 Auckland homes and businesses lose power, for up to 48 hours in many cases, after a cable fire at Transpower's Penrose electricity substation
• Last Saturday - thousands of drivers and their passengers face delays of up to four hours after a crash between two motorcycles and a truck on Auckland Harbour Bridge.
• Tuesday night - about 15,000 internet users lose connections for up to 12 hours after a fault in the Chorus network.
• Thursday morning - about 3000 rail passengers have their trips disrupted after an electric train breaks down on one of two line outside Britomart station.