Singapore has come out second in terms of transport fare affordability in a study of 12 major cities conducted by the Nanyang Technological University (NTU).
Commissioned by the Public Transport Council (PTC), the study also found that Singapore collected the least fare revenue per passenger kilometre travelled among the cities surveyed.
This, the authors warned, was "not necessarily sustainable for public transport operators given the rising operating costs worldwide".
Fare affordability was measured as the proportion of disposable household income spent on public transport for the second quintile household group - referring to the income group just above the bottom 20 per cent who take public transport - in 2016.
This is in line with the PTC's monitoring of fare affordability for this category, seen as the group most likely to depend on public transport regularly.
The study compared 12 cities - Beijing, Hong Kong, London, New York City, Paris, San Francisco, Seoul, Singapore, Sydney, Taipei, Tokyo and Toronto.
Singapore had an index score of 4.8 for affordability - meaning that on average, a typical family using public transport on a daily basis here spends about 4.8 per cent of its disposable income on public transport.
San Francisco scored 4.1, topping the list. While public transport expenditure in the American city is 28 per cent higher than in Singapore, the disposable income is 48 per cent higher.
The findings are in line with a report by consulting firm McKinsey in June, which ranked Singapore top for affordability. The report pointed to the 2013 fare review - which introduced measures such as a 15 per cent discount on adult fares for low-wage workers - as a "major step towards affordability" for the Republic.
The NTU study also found that in 2016, fare revenue per passenger kilometre in Singapore was 11 cents for the entire public transport system. In comparison, fare revenue for London was the highest at 19 cents per passenger kilometre.
This means that for an average trip of 10km, Londoners paid at least 80 cents more than commuters here.
The study said the PTC needs to "strike a better balance between fare affordability and cost recovery" in order for the Republic's public transport system to be more self-sufficient.
Singapore University of Social Sciences transport economist Walter Theseira agreed, saying: "We need to have in place a robust system of having commuters paying a reasonable fare for the service that they're getting."
The Straits Times reported last month that transport fares could go up by as much as 4.3 per cent - or 10 cents a journey - next year.
During the debate on his ministry's budget in March, Transport Minister Khaw Boon Wan said cheap fares were not sustainable.
"While transport fares must be affordable, we must be careful that they are not priced too cheaply, as maintaining a high-quality transport system requires resources," said Mr Khaw at the time.