When an emergency call comes in, Mr Joshua Sham, 38, puts on a black vest and springs into action.

He is not a law enforcement officer but a member of the emergency response team of the Migrant Workers' Centre (MWC).

Along with 15 colleagues, Mr Sham, the centre's assistant director of operations, answers calls for help from foreign workers involved in emergencies such as fires, worksite accidents or salary disputes.

When an emergency happens, a group of three to five members is sent to the incident site or hospital to talk to workers and ensure employers follow up with proper documentation or compensation.

Other foreign worker advocacy groups such as Humanitarian Organisation for Migration Economics (Home) said that while they did not have an emergency response team, they give assistance to workers who are going through problems like salary disputes.

The team was in action after an uncompleted road viaduct near Upper Changi Road collapsed in the early hours last Friday, resulting in the death of a Chinese worker and injuring 10 other workers.

"I got the message via WhatsApp around 4am... After we established which hospital the workers were at, we rounded up a team and headed there," said Mr Sham.

The centre's staff, who can speak languages and dialects spoken by foreign workers, take turns to go on operations mostly led by Mr Sham or MWC executive director Bernard Menon.

Mr Sham, a former policeman, joined MWC in 2015 as he felt he could do more for foreign workers as part of the non-governmental organisation. "I feel my position now lets me assist workers and follow up with them even after incidents."

The team usually handles about five big cases a month and are notified via their hotline, social media or the news, said the centre's operations specialist Ishrat Khan, 27. "We get calls late at night. Sometimes workers are stranded and have nowhere to go and that's considered an emergency as well."

About three years ago, the team got a tip-off that some 60 workers planned to go on strike and walk across Singapore to protest against the delayed payment of their wages.

Said Mr Sham: "We rushed down immediately to explain the laws in Singapore to them and advised them not to take matters in their own hands. Fortunately they were cooperative, and their employer also agreed not to escalate the matter."

MWC operations manager T. Nakulan, 38, a former teacher who joined the centre in 2015, was called away from a friend's wedding to a dormitory in Bedok in his first emergency operation.

The centre had got word that about 50 workers had been locked in their dorms. This was apparently to keep them safe but was risky in the event of a fire, he noted.

The team roped in the police and Ministry of Manpower to help.

Said Mr Nakulan: "There I was in my bright orange shirt, taking part in a covert operation. But jokes aside, that day I learnt what it felt like to be on the ground and walking the talk to help workers in need."