A company already facing $900,000 in fines for failing to clear Ontario highways in 2014 is under investigation again by the Ministry of Transportation after a series of accidents in Peel and Halton regions on New Year's Day.

The ministry is checking to see exactly when Carillion Canada dispatched salt spreaders and how much salt was applied on the Queen Elizabeth Way and on sections of Highways 400, 401, 403, 410 and 427 during a Jan. 1 storm.

About 20 accidents were reported on highways west and north of Toronto that day, and the ministry says the "weather-related" mishaps were a factor in deciding to conduct a full review of Carillion's actions.

Carillion, which has 6,000 employees in Canada and 40,000 worldwide, was awarded eight of Ontario's 20 road maintenance contracts, worth a total of $87 million per year.

The company is still fighting the fines levied by the ministry for failing to properly clear the QEW of snow and ice during storms in November and December 2014.

A Transportation Ministry spokesman says talks with Carillion on the size of the fines are continuing, and mediation or even litigation could be needed to reach a final agreement.

Transportation Minister Stephen Del Duca said the investigation into the 2014 storms found Carillion was late in deploying snow clearing and de-icing equipment, and did not apply enough salt on the highway.

"I take my responsibility with winter driving safety very seriously and, as keeping Ontario's roads safe is a shared responsibility, I expect all of our contractors and their employees to do the same," Del Duca said in a statement.

The opposition parties say the Liberal government lowered standards for road maintenance contracts in 2009 to reduce costs, which they blame for dangerous driving conditions during the winter months.

"The Liberals were caught last year lowering safety standards on our highways just to save a few bucks," said Progressive Conservative transportation critic Michael Harris.

"We now know that the Liberals' mismanagement has created even more dangerous driving conditions on the winter roads, putting the lives of motorists at risk."

Ontario's auditor general found that the government did save money on road maintenance contracts, but at a cost that included taking twice as long to clear highways of snow or ice than it did previously, nearly five hours in some cases.

The auditor also reported the government had waived $4.8 million of $13.3 million in fines levied against contractors in the winter of 2013-14.

The New Democrats asked the government to release all the non-compliance reports on all road maintenance contractors, and the results of the latest investigation into Carillion.

"Last year, Ontario's auditor-general reported that private road maintenance companies are using less salt and de-icing fluid," said NDP transportation critic Wayne Gates. "So far, it looks like the ministry hasn't solved the problems."

The Liberal government came under fire after admitting some of the companies awarded road maintenance contracts did not have the equipment to do the job.

Carillion did not respond to requests for comment on the latest investigation or its fight against the $900,000 in fines imposed in 2014.