TORONTO - Starting this fall, commuters in the Greater Toronto Area will be able to get their money back if their GO Transit train is more than 15 minutes late, Ontario's governing Liberals said Monday.

The money-back guarantee will affect all GO train commuters, the government said. But refunds won't be offered when delays are caused by extreme weather, police investigations, accidents or medical emergencies.

GO Transit already has a good record for running trains on time about 95 to 97 per cent of the time, said Economic Development Minister Brad Duguid. The exceptions to the guarantee are circumstances beyond GO Transit's control.

"The things the system can control -- breakdowns and maintenance -- those are things that are within the realm of control with GO Transit, so those are the kind of things that will be honoured if there is a delay," he said.

"Seventy per cent of the time when there's a delay, there would be a money-back guarantee," Duguid added.

About 170,000 GO riders who use the electronic Presto card system will get a refund automatically, but other commuters will have to apply for it -- probably online, he said.

But the minister couldn't provide an exact date when the service guarantee will take effect, saying it will be announced this summer.

Providing the refunds will cost the province about $8 million a year, including the cost of administering the system, Duguid said.

The money-back guarantee will not only make customers happier and boost the number of people using public transit, but will also provide an "extra incentive" to GO Transit to make sure the trains are running on time, Duguid said.

"This is a way of improving public service ... taking a private-sector principle, a money-back guarantee, and embedding it into the public service," he said.

Premier Dalton McGuinty floated the idea of a GO train guarantee last June before the fall election campaign and included it in his platform.

It's a step in the right direction, said NDP Leader Andrea Horwath.

"(Commuters) want to know that their train is going to be able to get them to work on time and that they're going to be able to get home on time to spend time with the family," she said.

"What I would say though, is that a lot more focus needs to be on making that transit system reliable, and not just on a rebate scheme."

The GO Train guarantee doesn't address the real problem: running transportation systems efficiently and on time when the province is facing a $15-billion deficit, said Progressive Conservative Leader Tim Hudak.

"I think it's more important to make sure the trains get to the station when they're supposed to and have quality of service instead of doing gimmicks," he said.

GO Transit, a division of the provincial agency Metrolinx, said it runs more than 180 train trips and over 2,100 bus trips carrying about 217,000 passengers on a typical weekday.