As the voices singing Happy Birthday trailed off, 78-year-old Lee Kee Siang made a wish and with three heavy puffs, blew out the candles on a mango cake.

A passerby might not give the scene a second look but the gathering last month was an unusual party as they tucked into packets of chicken rice. Besides his daughter and granddaughter, Mr Lee barely knew the people gathered around him at the void deck of a Henderson Crescent block near where he lived.

There was Danish expatriate Pernille Bussone and her family.

Ms Bussone, 36, had invited her friend, Madam Tan Geok Hak, 87, whom Mr Lee had never met. Finally, there was Mr Chua Beng Wan, 40, the party organiser.

What connected them all was a distinctive trishaw parked nearby.

With its black frame, red hood, and a passenger seat installed in front, the 60kg machine stood out from the familiar pedal-powered vehicles that ferry tourists around the city.

Ms Bussone had shipped the trishaw from Denmark to Singapore in June last year, under a global non-profit initiative that offers free trishaw rides to elderly people at risk of being lonely and depressed.

A Danish university paid the $6,000 bill for the trishaw.

The programme, called Cycling Without Age, was founded by Danish social entrepreneur Ole Kassow, 50, in Copenhagen in 2012.

Said Ms Bussone: "It lets them feel the wind in their hair, helps reconnect communities, and gives the young and old a sense of belonging to their cities."

The mother of two had moved to Singapore in 2014, with her husband Jakob Hjortlund, 37, a shipping manager and two children, Gabriel, eight and Veronika, five.

She began the pilot project last year driven by her love for cycling and a desire to reach out to seniors. Singapore is Cycling Without Age's only branch in Asia.

It has been adopted in more than 20 countries in Europe, Australia, New Zealand and North, South as well as Central America, since it was launched four years ago.

There is only one such trishaw here, and Ms Bussone is its main rider. She has trained more than 40 volunteers to give joyrides to seniors from organisations like The Salvation Army.

It was at The Salvation Army that she met Madam Tan, whom she would take for a ride every week around Singapore.

"She is active, curious and I like to explore Singapore with her,'' she said of her favourite passenger who lives in a three-room flat in Bukit Ho Swee.

Mr Chua, a volunteer, met Mr Lee last month, when he gave him a ride along the Alexandra park connector on the trishaw.

During the hour-long journey, he found out that Mr Lee's wife has heart disease and his daughter and granddaughter were also in poor health.

"I wanted to take them out of their daily routine and worries by celebrating a joyous occasion," said the scientist in a research and development company.

While Ms Bussone relishes how the initiative builds relationships between people who otherwise will never interact, training the volunteers to operate the trishaw is time-consuming.

Also, she usually delivers the trishaw personally, riding it from her River Valley home to the meeting point agreed on by the volunteer and passenger.

The Salvation Army and St Luke's ElderCare Centre are among the organisations that use the trishaw.

Two similar trishaws, donated by a Danish IT company in Singapore, will arrive at The Salvation Army next year.

Ms Bussone's trishaw has brought joy to more than just seniors.

Ms Nancy Chew found it the perfect birthday surprise for her husband William Tan, 46, who is paralysed on the left side of his body after a stroke five years ago.

The 45-year-old administrator found Cycling Without Age while searching the Internet for ways to cycle with her husband on his birthday in June.

Instead of pushing him in a wheelchair around their Tampines neighbourhood, she pedalled him to Bedok Reservoir.

"It brought back memories of how we used to cycle together," said Ms Chew, who plans to take her husband of 12 years to Coney Island on their next trishaw ride next month.

Ms Bussone hopes her effort will inspire others and lead to every estate having a trishaw for Singapore's growing senior population as well as people with disabilities.

She has also approached regulator Land Transport Authority (LTA) to get a nod of approval for the trishaw, which can be turned into a motorised, battery-powered vehicle that can travel at up to 25 kmh.

LTA is looking into her request.

Its spokesman told The Straits Times: "LTA is currently assessing how we can support this meaningful social initiative by Cycling Without Age, while taking into account the safety of its beneficiaries as well as other commuters."

Meanwhile, Ms Bussone has intensified her search for an individual or organisation to take over Cycling with Age as she and her family will probably return home in three months' time.

"I love trishaws, so I want to give this to Singapore," she said.