Major roads are the priorities for crews driving Calgary sanders and graders. (CBC)

Calgary road crews are working as many hours as labour legislation allows to clear streets of snow, the city says.

The city has had a minimum of 56 sanders and 33 graders on the roads since a major snowfall six days ago, roads maintenance spokeswoman Kelsey Strachan said Thursday.

"We think it's enough," she said. "Because we have trucks for all of our priority one and two routes, we're responding appropriately."

The city is operating on a Level 2 response, which focuses on major roads with traffic exceeding 20,000 vehicles per day, designated emergency routes and trouble spots.

"A Level 2 response we can sustain indefinitely, and considering the fact that it's going to be cold for probably about another week, we need to be able to sustain our forces out on the road," she said.

'We do have the crews we need to staff those equipment, but fatigue management is becoming an issue for us right now.'— Kelsey Strachan, city spokeswoman

Some workers have been putting in 16-hour shifts, and racking up the overtime.

About 75 other pieces of equipment are sitting idle because of restrictions under Alberta labour regulations, she said.

"Our crews have been going flat-out since last Friday so … once they've been working a certain number of hours they do need to take a certain length of time off, and that's just in compliance with labour regulations," Strachan said.

"So we do have the crews we need to staff those equipment, but fatigue management is becoming an issue for us right now."

Strachan said the city will start plowing secondary roads after 24 to 48 hours of clear skies. But with more snow forecast, it will be a while before crews get to that point.

Concern over roads in school, playground zones

Because top priority is given to major roadways, many school and playground zones located in residential areas are often the last areas to get sanded and cleared.

"I see a lot of people speeding through school zones and if a child were to pop out in front of a bus or a car there would be no hope," said parent Donna Stefura.

Officials with the Calgary Board of Education say they've asked the city to move school areas up on the priority list.

But Rick Sample, an operations engineer with the City of Calgary, said crews work according to priorities approved by city council.

"And until council gives us different direction that's what we have to do," he said.

Ald. Ric McIver said council relies on recommendations from experts, and until there's a renewed call to make school zones more of a priority, things will remain as they are now.

Calgary police continue to warn motorists to drive with caution after responding to more than 800 collisions in the last week.

Red Deer RCMP maintained a warning Thursday that drivers avoid "non-essential travel" on Highway 2, as blowing snow, reduced visibility and icy roads have created extremely poor driving conditions.