Thousands of selfie-taking Ho Chi Minh City residents crammed into train carriages on Sunday as the traffic-clogged business hub celebrated the opening of its first-ever metro line after years of delays.

Huge queues spilled out of every station along the $1.7bn line that runs almost 20km (12 miles) from the city centre – with women in traditional “ao dai” dress, soldiers in uniform and couples clutching young children waiting excitedly to board.

“I know it (the project) is late, but I still feel so very honoured and proud to be among the first on this metro,” said office worker Nguyen Nhu Huyen after snatching a selfie in her jam-packed train car.

“Our city is now on par with the other big cities of the world,” she added.

It took 17 years for Vietnam’s commercial capital to reach this point. The project, funded largely by Japanese government loans, was first approved in 2007 and slated to cost just $668m.

When construction began in 2012, authorities promised the line would be up and running in five years.

But as delays mounted, cars and motorbikes multiplied in the city of nine million people, making the metropolis hugely congested, increasingly polluted and time-consuming to navigate.

The metro “meets the growing travel needs of residents and contributes to reducing traffic congestion and environmental pollution”, the city’s deputy mayor Bui Xuan Cuong said.

Cuong admitted authorities had to overcome “countless hurdles” to get the project over the line.

Back on the train, 84-year-old war veteran Vu Thanh told the AFP news agency he was happy to experience below-ground in a more positive way after spending three years fighting American troops in the city’s famous Cu Chi tunnels, an enormous underground network.

“It feels so different from the underground experience I had years ago during the war. It’s so bright and nice here,” he said.

Professor Vu Minh Hoang at Fulbright University Vietnam warned that with just 14 station stops, the line’s “impact in alleviating traffic will be limited in the short run”.

However, it is still a “historic achievement for the city’s urban development”, he told AFP.