Last week, Transport Minister Raymond Lim, acceding to public clamour, said the new rule will kick in soon.

School bus operators The Sunday Times spoke to estimate that fees might rise by 50 per cent or even more.

This is regardless of whether current buses are retrofitted or new buses come fitted with belts, since only fewer children can be accommodated now.

The Sunday Times also spoke to 50 parents whose children take the school bus.

The majority said they were not happy with having to pay more for school bus fees. All said they were prepared to pay at most 20 per cent more than the current fees.

One parent said it might be time his 10-year-old son 'learnt to take public buses'.

The operators explained why they reckoned fees may need to go up by half.

'It's not just the cost of installing belts. Each bus can now fit fewer children. So there is also a permanent loss of income for the operators,' said Mr Wong Ann Lin, chairman of the Singapore School Transport Association (SSTA).

With the new seat-belt policy, a minibus which can normally seat 15 children will need to be reconfigured, with space left for only 10 seats.

Losing five students per bus at $100 each would mean a $500 loss in income per month for the operators. Moreover, it costs about $80 for a shoulder belt and $25 for a lap belt. If new seats for such belts are needed, these can cost between $150 and $230 each.

Imported buses are typically 'empty' inside. They are then fitted with seats and seat belts according to the requirements of the operators, said Mr Michael Wong, president of the Motor Traders Association of Singapore.

Most parents now pay $65 to $100 as school bus fares. If fares are increased up to 50 per cent, they will have to pay $100 or more.

The Government gives 'targeted help' for needy families to cope with rising costs of living, including increased school bus fares. Last week, Transport Minister Raymond Lim said there will be no 'across the board' subsidies.

In spite of the operators' explanation, several parents interviewed said they were not happy to pay more for something 'school buses should have installed from the start'.

While agreeing that their children's safety is paramount, they said the additional costs should not be passed to them. Instead, bus operators should absorb the cost.

Said businessman Jeffrey Lim, 37, who pays $75 for his son's bus fare: 'Why must parents be punished because bus operators didn't have the foresight to install seat belts earlier? This is unfair.'

Many felt it would be a lot to pay for such a brief bus ride. Most students live just five to 10 minutes' drive away from their schools.

'It only takes five to 10 minutes for my son to reach his school. I feel that for that distance, the fares are already very expensive,' said Madam Nancy Yeo, 40, a manager with a packing firm. She pays $75 monthly for her son's bus fare.

Some said they could accept a one-off payment, but not a permanent monthly hike.

A handful of parents said they might have to pull their children off the school buses.

Said sales officer Eric Yeo, 51, whose 10-year-old son takes the school bus: 'I'm already paying $70. I'm not going to pay over $100. Maybe it's high time he learnt to take public transport.'

Additional reporting by Samantha Eng, Aw Cheng Wei and Terence Lee

ndianah@sph.com.sg

Will you stop using school buses if they charge 50 per cent more after installing seat belts? Visit straitstimes.com to vote.

This is the final part of The Sunday Times' road safety series.