Snow-clearing is usually an intermittent business, but Halifax has a backup system for snowfalls on the heels of other snowfalls: it sends some streets and sidewalks to the back of the line.

"In the case of multiple snowfalls, where there has been insufficient time to complete all streets and sidewalks, operations will return to the highest priorities and start over," says the municipal website on snow-clearing standards.

If some residential streets seem to be getting shorter shrift than others that seem similar, it's probably because they're designated differently.

Some residential streets, such as Vestry Street and Joffre Street, are classified as first priority residential streets serving as "snow routes." They have a slope greater than 10 per cent.

The goal for those streets is to start clearing within three hours, after ten centimetres of snow. By 12 hours after the end of the snowfall, there should be a two-lane width.

Residential streets pushed down to-do list

Other residential streets like Cork Street, Anderson Street and Chandler Drive don't get cleared until they've seen ten centimetres of snow, and won't have two clear lanes until 24 hours after the snowfall — assuming there isn't a new snowfall a day later that sets operations back to where they started.

Residential sidewalks that aren't in school zones or bus routes, with a 36-hour plowing deadline, have even less chance of getting cleared in a multiple snowfall week.

Halifax Regional Municipality said earlier this week they may not meet all service standards. Early Friday afternoon they said the top-priority roads — including main arteries and emergency vehicle routes — were more than half done after Thursday's snowfall.

'Full complement' of drivers

Staffing levels are holding up, says municipal spokeswoman Tiffany Chase.

Snowplow operators need to be scheduled to get enough rest in between shifts. More are scheduled to work at night, when there's less traffic, than during the day, said Chase.

"We operate in shifts, as do our contractors," she said.

"At times there are more staff on shift than others ... but we continue to operate with a full complement following last night's storm."

The crews won't stop working until all streets and sidewalks are cleared to the standards set for them, she said.

"We do hope to get a break before the next one arrives," she said.

More snow is forecast for next week.