Dublin has placed 19th on an index of "smart cities" but been singled out for its traffic woes.

The new report from Bank of America Merrill Lynch ranks Singapore, London, New York, Paris and Tokyo as the smartest cities in the world, with Dublin slotting between Auckland and Sydney, in 18th and 20th place respectively.

Broadband coverage and next generation infrastructure were a couple of factors measured in compiling the index.

The Irish capital also placed 19th when it came to gross domestic product (GDP) per capita, valued at $63,000.

Zurich came out on top, with GDP of $82,410 per capita in the Swiss city, as per Brookings Institution figures.

One major impediment to future growth, according to the report, is Dublin's problem with traffic congestion.

It was, in fact, ranked as the "slowest-moving" major city in the world. According to INRIX 2016 Traffic Scorecard data, Dublin traffic moves at just 7.5km per hour during times of congestion, with rush-hour speeds of a mere 5.5km per hour – "slower than a horse and cart".

The report warns that congestion could cause a loss of up to 4% of GDP due to lost time, increased business costs and wasted fuel.

US cities made up 11 of the top 25 cities with the worst congestion, but all of them allowed for swifter comparative commutes than Ireland.

Los Angeles drivers spend more time behind the wheel than their counterparts in any other city, with an average of more than 100 hours stuck in their vehicle in 2016 alone.

When it comes to the affordability of urban housing, Ireland is faring better than the US, Canada, Japan, the UK and Singapore.

China, Australia and New Zealand were ranked as the least affordable.