Snow Removal - Clearing By Cities

Clearing By Cities

Cities clear snow on a much larger scale than individuals. Most cities in areas that get regular snowfall maintain a fleet of snow clearing vehicles. The first to be dispatched are gritters who do some plowing but also salt the road. The salt, via freezing point depression, helps melt the snow and ice and also gives vehicles more traction. Later, usually when the snow has ceased falling, snow plows, front end loaders with snowplow attachments and graders cover every street pushing snow to the side of the road. Salt trucks often then return to deal with any remaining ice and snow. The trucks generally travel much faster than the plows, averaging between 30 and 40 kilometers per hour. Most cities thus have at least twice as many plows as trucks. Smaller narrow body plows, with Caterpillar tracks or huge snow tires salt and clear sidewalks in some cities, but in many others with less snowfall and/or less pedestrian traffic individuals are tasked with clearing the sidewalk in front of their homes. Ecological movements often oppose this use of salt because of the damage it does when it eventually washes off the roads and spreads to the environment in general.

In cities where snow steadily accumulates over the winter it is also necessary to remove the piles of snow that build up on the side of the roads known as windrows or snowbanks. There are a number of methods of doing this. Pulling snow is done when temperatures rise high enough for traffic to melt snow. The windrows are then broken up and spread over the road. Casting is the moving of snow by means of a shovel or plow to nearby public lands. On boulevards or highways winging back is done, which consists of pushing the snow banks further from the road. The most expensive option, but necessary when there are no nearby places to dump the snow, is to haul it away. This is most often done by large self propelled snowblowers that gather the piles of snow at the side of the road and load it into dump trucks. The snow is then dumped on the outskirts of town, or in a nearby lake, river or harbor. (Some jurisdictions have banned dumping snow into local bodies of water for environmental reasons - modern roads can be contaminated with melting salt, motor oil, and other substances.) Snow melting machines may be cheaper than moving snow, depending on the cost of fuel and the ambient temperature.

The windrows created by the plows in residential areas often block driveways and imprison parked cars. The snow pushed there by any plow is a dense, packed version of "normal" fallen snow. When the temperatures are significantly below freezing this packed snow takes some of the characteristics of solid ice. Its removal is nearly impossible without mechanical means.

The largest roads and highways are the first to be cleared; roads with steep hills or other dangers are also often a priority. Streets used by buses and other mass transit are also often given higher priorities. It often takes many hours, or even days, to cover every street in a city. In some places, a snow emergency will be declared, where automobile owners are instructed to remove their vehicles from the street (or one side of a street). If cars are in the way when the plows come around, they may be hauled away by tow trucks. Some communities have standing snow emergency rules in winter, in which vehicles may not be parked on streets overnight, whether it snows or not. After smaller snow storms only main roads are cleared while residential ones are left to be melted by passing traffic. Decisions on immediate removal versus "natural melting" can be hard to make because the inconvenience to citizens and the economy in general must be weighed against the immediate effect on the snow removal budget at that particular moment in the season.

In large cities with heavy snowfalls like Montreal and Ottawa, the snow clearing expense for each season is an important part of the seasonal public works budget and each snow storm provokes a major logistical operation involving thousands of employees working in shifts 24 hours a day. The effort can vary greatly depending on the amount of snow. Montreal gets about 225 cm of snow each winter and spends more than $128 million Canadian each year to remove it. Toronto, with about 50 per cent more population and 28 per cent more road surface, gets only 125 cm of snow a year and spends about half that. The higher cost in Montreal is due to the need to perform "snow removal" as opposed to simple "snow clearing" necessitated by both the high snowfall amounts and fewer melting days.

In Helsinki, Finland, the amount of snow transported from streets and properties to snow dump sites during the winter of 2009–2010 was 210,000 truckloads, equaling over 3 million cubic meters.

Snow removal impacts the design of city infrastructure. Where possible, street boulevards are wider to accommodate the windrows and sidewalks are not right next to the street. Fire hydrants will have tall flags to locate them under the windrows. Reflective traffic lane markers embedded in the roadbed is not possible (or much harder) due to risk of damage by plows. Access to snow dumping locations (e.g. ravines) by heavy equipment is also planned.

It is estimated that Canada spends $1 billion on snow removal. The employees who do this work are generally the same workers who do road maintenance work during the summer months, but in some US cities garbage trucks are also equipped with plows and used for snow removal. Many smaller US communities sign contracts with insurance companies, under which the insurance company assumes the risk of a heavy winter. The insurance company of course sets the rates such that averaged over time they will make a profit; the town is willing to overpay for snow removal in mild winters in order to avoid the risk of running dramatically over budget in the occasional severe winter.

Large organizations such as universities and airports also often have their own mechanized snow clearing force. Public transit systems generally clear bus stops while post offices clear around mail boxes. Railroads have their own snow clearing devices such as rotary snowplows.

Airports, with their associated runways, taxiways and ramp areas are an exception to the use of salt, as the metals used in aircraft construction will corrode causing safety issues.