A northwestern Ontario school bus operator is refusing to use Highway 502 due to concerns it's not adequately maintained.

Iron Range Bus Lines' Fort Frances manager Camie Gray says for the first time, buses aren't using the highway between Dryden and Fort Frances because the journey is too dangerous.

"When you have a bus-load of children, and you're coming down a hill, and you have to have enough speed to get up to the top of the next hill, but there's deep ravines, on both sides and it's glare ice, it just is not safe," said Gray, describing a typical danger faced by Highway 502 commuters.

The Highway 502 route from Fort Frances to Dryden takes about 2.5 hours, says Grey, while the alternate route via Highway 71 takes about 4 hours by bus.

She says the change means schools have to pay more to ferry children, as Iron Range charges by the kilometre. Additionally, any trips to Sioux Lookout are now "overnighters," using Highway 71, as drivers can only work up to 14- hour days, Grey says.

Grey says that rerouting is necessary as the company does not want to risk busing people on a highway covered by a thick ice layer and dotted with ruts.

A spokesperson for the Ministry of Transportation says Highway 502 is a Class 5 route. That means the road must be cleared to a snow pack within 24 hours after a storm ends. Transfield Services is in charge of clearing Highway 502.

Whether or not the maintenance contractor is meeting MTO requirements is not information the ministry makes public, the MTO spokesperson told the CBC in an e-mail.