SINGAPORE - Reports of crowded trains on the first day of lower service frequency has prompted Transport Minister Khaw Boon Wan to ask for a review of service reductions which kicked in this week.

Mr Khaw wrote on his Facebook page on Saturday (April 18) that the service adjustments had "caused some crowding in some stretches" of the North-South, East-West and Circle lines on Friday - the first day when public transport service was pared down to reflect the 70-75 per cent drop in ridership demand.

In response to queries from The Straits Times earlier, the Land Transport Authority said it was monitoring the situation, and would make the necessary adjustments.

Mr Khaw said: "I have told LTA to err on the side of generosity. That is, to over-provide rather than under-provide."

He said that during this circuit breaker period, the "priority is safe distancing and ensuring our essential workers can reach their work places safely and punctually".

On Friday, MRT service intervals were five minutes and 10 minutes for peak and non-peak periods respectively - down from two minutes and five minutes before the coronavirus outbreak prompted people to work from home and all students to go on home-based learning. But, according to some commuters, intervals were as long as 12 minutes.

Several bus services were also suspended, mostly express and night services.

But, as a result, commuters found themselves on packed trains, and some, on crowded buses. They took to social media to vent their frustration, asking how they were supposed to exercise safe distancing in such a situation.

Photos of packed train carriages were also widely circulated, showing commuters occupying even spaces marked out by safe distancing crosses.

Among those reacting to the public outcry was Professor Teo Yik Ying, dean of the Saw Swee Hock School of Public Health, who told ST: "Reducing service frequency is a fair response (to the drop in demand), but it should be done off-peak.

"During peak, there are essential workers who need to travel by public transport for work."

Having crowded public transport, he said, would thus be "counter to our circuit breaker objectives".

Prof Teo told ST that the top priority was for commuters to be able to practise safe distancing. With the lower service frequency, this may not be possible.

"Human psychology is such, if you know the next train is 10 minutes away, you will not wait. You will squeeze onto the one in front of you," he said.

He said that going by the many posts on the topic, the "situation is frustrating for many", and added that he hopes service frequency can be adjusted quickly.

Humour writer Neil Humphreys found it no laughing matter. He wrote scathingly on Facebook: "MRT , this is not good enough. Essential workers must still work. One train every 10 minutes makes it impossible to social-distance properly.

"Well, I was on a train where everyone tried their best - but trains were more than 10 minutes apart. Unheard of. This is dangerous cost-cutting. Health or economy? Which is it?"

Singapore University of Social Sciences transport economist Walter Theseira said: "The principle behind service reductions to save public money is sound, as services cannot break even with low passenger loading.

"But clearly fine-tuning is needed. It may be that the essential services employers have to be required to implement staggered opening and closing times to spread out the load.

"Otherwise, it will be very difficult to reduce services and maintain safe distancing."