Mr Muhammad Nazreen Osman often meets his university coursemates but these reunions are not held over dinner or a cup of coffee.

Instead they happen at the Downtown MRT station where Mr Nazreen, an SBS Transit rail engineer, sometimes works, while his friends, all suited up, head off to their jobs at financial institutions in the Marina Bay area.

"The majority of my cohort ended up in the financial line," said the National University of Singapore civil engineering graduate.

Mr Nazreen said more lucrative pay attracted his peers to other industries. The 28-year-old, who works on the Downtown MRT line, added: "Engineers have to get their hands dirty, which is not appealing to some people."

He stayed in engineering because of his passion for the field, he said.

While Mr Nazreen, who joined SBS Transit in 2014, works office hours on most days, he has to work past midnight once or twice a week for maintenance work. This includes grinding worn rail tracks to restore their original profile.

Sometimes, he also gets called out of bed to attend to problems such as burst water pipes. "You always have to be alert and have your phone nearby because anything can happen at night," he said.

Mr Nazreen, who got married last year, said his wife has become used to his schedule. "She gives me the occasional frown but she's used to it."

Mr Nazreen is working to achieve chartered rail engineer status, a form of professional accreditation.

Criticism of rail reliability here does not dishearten him, he said. "It encourages us to work even harder."