Some Ottawa students return to class today for the first time in six days due to a record-breaking snowfall and two days off, but just across the border in Quebec, school buses have kept on trucking for English students in spite of the inclement weather.

Why the difference?

Jim Shea, chairman of the Western Quebec School Board, said it's because their buses are equipped with winter tires and also because they prefer to cancel buses on a bus-by-bus basis.

For example, if a particular road is dangerous to pass during a spate of bad weather, a decision is made to cancel the bus that travels it, instead of every bus in the system.

On Tuesday, as about 50 centimetres of snow fell in the region, the western Quebec board cancelled three after-school buses due to poor conditions, Shea told CBC Radio's Ottawa Morning on Thursday.

They haven't had a system-wide snow day cancellation of bus service in years, he said.

'We do the best that we can'

"We all have children, we all want to make sure that they're safe and secure ... and on the way [to school] it's our responsibility to transport them safely. So we do the best that we can," he said.

Vicky Kyriaco is general manager of the Ottawa Student Transportation Authority, or OSTA, which handles school buses for the Ottawa public and Catholic English school boards.

OSTA buses use all-season tires, not winter tires, but Kyriaco called them "quite robust."

It would be very expensive to equip all OSTA buses with winter tires, she said, and added there's not much evidence they're safer, especially during freezing rain spells.

She also expressed concern about the vulnerability of children standing at bus stops close to roads when other drivers are out in freezing rain.

Shea said he's not sure if snow tires are safer, but they work for the western Quebec board.

"I don't know if that makes a difference or not, but the reality is snow tires are mandatory in Quebec, and it seems to, on a day like [Tuesday], ... work," he said.