Snow removal is the job of removing
snowSnow is a type of precipitation in the form of crystalline water ice, consisting of a multitude of snowflakes that fall from clouds. Since snow is composed of small ice particles, it is a granular material. It has an open and therefore soft structure, unless packed by external pressure. Snowflakes...
after a snowfall to make travel easier and safer. This is done by both individual households and by governments and institutions.
Clearing by individuals
In countries with light snow, brooms can be used to brush off snow from walks and other surfaces. In colder regions with more precipitation, the main tools of the private snow clearer are the snow shovel, a large lightweight shovel used to push snow and lift it, and the snow scoop, a large and deep hopper-like implement fitted with a wide handle and designed to scoop up a load of snow and slide it on any slippery surface to another location without lifting. Shovelling entails a considerable amount of work and can be a strain on the
back-People:*Adam Back*Charles Back*Ernst Emil Alexander Back*Frédéric Back*George Back*Natasja Crone Back*Neil Back*Ralph-Johan Back-Places:* Back Peninsula, Nunavut* Back, Outer Hebrides, a village on the Isle of Lewis, Scotland*Back , lunar crater...
and the
heartThe heart is a muscular organ found in all vertebrates that is responsible for pumping blood throughout the blood vessels by repeated, rhythmic contractions...
. Each year many senior citizens and middle aged persons die from heart attacks while shovelling snow. Those unwilling or unable to labour, especially those with large
drivewayA driveway is a type of private road for local access to one or a small group of structures, and is owned and maintained by an individual or group....
s or other substantial surfaces may use a
snow blowerAlthough the proper name is snow thrower, some people still use the name snow blower or snowblower. A snow thrower is a machine for removing snow from an area where it is not wanted, such as a driveway, sidewalk, roadway, railroad track or runway...
, as well as people that live in areas with long lasting winters with large amounts of snowfall. Others may hire a contractor with a plow bearing truck or a shovel. After a large snowfall businessmen with plow trucks often drive through cities offering to plow for money. A recent technological advance is the
snowmelt systemA snowmelt system is used to remove snow and ice via embedded electric cables or hydronic PEX tubing. Common areas for snowmelt systems are: driveways, walkways, parking areas, stairways, loading docks, and around car washes. A snowmelt system is usually installed during the original construction...
that heats the pavement from below and melts snow and ice after a period of time. Such systems are expensive to install and operate and they are not cost effective in areas with very low winter temperatures and large snowfalls. Some governments offer free snow clearing for the elderly and others in need.
Dealing with ice is more difficult. Snow blowers are rarely effective. Picks are sometimes used, but a solid
spadeA spade is a tool designed primarily for the purpose of digging or removing earth. The first spade was made of riven wood. After the art of metalworking was discovered, spades were made with sharper tips of metal. Before the advent of metal spades manual labor was less efficient at moving earth,...
can break through most ice. There is always the risk of damaging the pavement with these instruments. Icy areas can be covered with
saltA salt, in chemistry, is an ionic compound, and can result from the neutralization reaction of acids and bases. Salts are ionic compounds composed of cations and anions so that the product is electrically neutral...
or some other substance, bags of which are widely available.
Clearing by contractors
Hiring a contractor with a winter service vehicle or a shovel.
In many high elevation or heavy snow accumulating areas, companies with snow removal equipment offer to provide services to remove the snow. Contractors may work on a per-time basis, full season contract, or will-call status. Per-time service (or per-push) is usually invoiced monthly and customers will be charged for each time services are provided. Some companies will charge per-time and per-inch where the depth of the snow is even taken into account. A full season contract is quoted and paid upfront at the start of the season and services will be provided automatically according to the contracted terms. All companies have different terms so make sure to understand the agreement. For example, some full season contracts will expire after X amount of trips where others are unlimited. And finally, will-call service is where the client makes contact with the snow removal company to initiate a single clearing. This is not an automatic service and charges are usually higher for will-call jobs.
Snow removal services may include driveway and parking area snow removal, walkway and deck handwork, and occasionally roof clearing. Contractors use hand shovels, walk behind snowblowers (or snow throwers), truck plows, skid-steers, light-weight tractors, and heavy front-end loaders. Many times, these machines will require use of tire chains to perform their tasks. Snow may be pushed by plowing methods or blown to an area of the property by snowblowers. Contracts may apply sand or salt in some locations to help melt ice accumulations.
Many snow removal contractors will require installation of snow poles or snow staking along the driveway. This is to keep equipment out of the landscaping and to help identify the perimeter of an area.
Contractors should be licensed and insured.
Clearing by cities
Cities clear snow on a much larger scale than individuals. Most cities in areas that get regular snow 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, generally once the snow has ceased falling,
front end loaderFront End Loader is an Australian rock band consisting of Davis Claymore , Bowden Campbell , Richard Corey , and Peter Kostic . Peter also drums for Regurgitator and The Hard-Ons.-History:...
s with snowplow attachments and
graderA grader, also commonly referred to as a road grader, a blade, a maintainer, or a motor grader, is a construction machine with a long blade used to create a flat surface. Typical models have three axles, with the engine and cab situated above the rear axles at one end of the vehicle and a third...
s 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 a least twice as many plows as trucks. Smaller narrow body plows, with Caterpillar tracks or huge snow tires salt and clear
sidewalkA sidewalk , pavement , footpath , platform or footway is a path for pedestrians that is situated alongside a road or a paved...
s in some cities, but in many others with less snow fall 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
windrowA windrow is a row of cut hay or small grain crop.It is allowed to dry before being baled, combined, or rolled. For hay, the windrow is often formed by a hay rake, which rakes hay that has been cut by a mower machine or by scythe into a row, or it may naturally form as the hay is mowed...
s 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 truckA dump truck or production truck is a truck used for transporting loose material for construction. A typical dump truck is equipped with a hydraulically operated open-box bed hinged at the rear, the front of which can be lifted up to allow the contents to be deposited on the ground behind the...
s. 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
busA bus is a road vehicle designed to carry passengers. A bus seats a maximum of 8 to 300 passengers...
es 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 emergencyA snow emergency is the term used in the United States and Canada to declared when a major winter storm severely impacts a city or county. In a snow emergency, schools, universities, government offices and other public buildings may close...
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 truckA tow truck , is a vehicle used to transport motor vehicles to another location , or to recover vehicles which are no longer on a drivable surface.Towing services are generally provided by an emergency road service operator...
s. Some communities have standing snow emergency rules in winter, where vehicles are not allowed to be parked on streets overnight, no matter if it snows or not. After smaller snow storms only main roads are cleared while residential ones are left to be melted by the 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
MontrealMontreal is the second-largest city in Canada and the largest city in the province of Quebec. Originally called Ville-Marie , the city takes its present name from Mont-Royal, the triple-peaked hill located in the heart of the city, whose name was also initially given to the island on which the...
and
OttawaOttawa is the capital of Canada and a municipality within the Province of Ontario. Located in the Ottawa Valley in the eastern portion of Southern Ontario, the city lies on the southern banks of the Ottawa River, a major waterway forming the local boundary between the Provinces of Ontario and...
, 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 225cm of snow each winter and spends more than $128 million Canadian each year to remove it.
TorontoToronto is the most populous city in Canada and the provincial capital of Ontario. It is located in Southern Ontario on the northwestern shore of Lake Ontario. With over 2.5 million residents, it is the fifth most populous municipality in North America...
, 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.
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 so as to avoid the risk of running dramatically over budget in the occasional severe winter.
Large organizations such as
universitiesA university is an institution of higher education and research, which grants academic degrees in a variety of subjects. A university provides both undergraduate education and postgraduate education...
and
airportAn airport is a location where aircraft such as fixed-wing aircraft, helicopters, and blimps take off and land. Aircraft may be stored or maintained at an airport...
s also often have their own mechanized snow clearing force. Public transit systems generally clear bus stops while
post officeA post office is a facility authorised by a postal system for the posting, receipt, sorting, handling, transmission or delivery of mail. Post offices offer mail-related services such as post office boxes, postage and packaging supplies...
s clear around
mail boxA post box , is a physical box intended for use by the general public in order to collect outgoing mail...
es. Railroads have their own snow clearing devices such as
rotary snowplowA rotary snowplow is a piece of railroad snowfighting equipment. It is characterized by the large circular set of blades on its front end that rotate as a unit to cut through the snow on the track ahead of it. In this way, a rotary snowplow is similar to a tunnel boring machine that was first...
s.
Surface treatments
Various salts and other substances are used on roads and walkways to induce
freezing-point depressionFreezing-point depression describes the phenomenon that the freezing point of a liquid is depressed when another compound is added, meaning that a solution has a lower freezing point than a pure solvent. This happens whenever a solute is added to a pure solvent, such as water...
, which (except in extremely cold weather) causes ice and snow to melt, greatly improving traction. These include:
- Sodium chloride
Sodium chloride, also known as salt, common salt, table salt, or halite, is an ionic compound with the formula NaCl. Sodium chloride is the salt most responsible for the salinity of the ocean and of the extracellular fluid of many multicellular organisms...
(common table salt, NaCl)
- Calcium chloride
Calcium chloride, CaCl2, is a common salt. It behaves as a typical ionic halide, and is solid at room temperature. It has several common applications such as brine for refrigeration plants, ice and dust control on roads, and in concrete...
(CaCl2)
- Potassium chloride
The chemical compound potassium chloride is a metal halide salt composed of potassium and chlorine. In its pure state it is odorless. It has a white or colorless vitreous crystal, with a crystal structure that cleaves easily in three directions. Potassium chloride crystals are face-centered cubic...
(KCl)
- Magnesium chloride
Magnesium chloride is the name for the chemical compounds with the formulas MgCl2 and its various hydrates MgCl2x. These salts are typical ionic halides, being highly soluble in water. The hydrated magnesium chloride can be extracted from brine or sea water...
(MgCl2)
- Ammonium nitrate
The chemical compound ammonium nitrate, the nitrate of ammonia with the chemical formula NH4NO3, is a white crystalline solid at room temperature and standard pressure...
(NH4NO3)
- Ammonium sulfate
Ammonium sulfate , 2SO4, is an inorganic salt with a number of commercial uses. The most common use is as a soil fertilizer. It contains 21% nitrogen as ammonium cations, and 24% sulfur as sulfate anions...
[(NH4)2SO4]
- Potassium acetate
Potassium acetate is a chemical compound.It can be prepared by reacting a potassium-containing base such as potassium hydroxide or potassium carbonate with acetic acid:...
(CH3COOK)
- Urea
Urea or carbamide is an organic compound with the chemical formula
2CO. The molecule has two amine residues joined by a carbonyl functional group....
[(NH2)2CO]
- Propylene glycol
Propylene glycol, known also by the systematic name propane-1,2-diol, is an organic compound , with a faintly sweet taste, and is a colorless, nearly odorless, clear, viscous liquid that is hygroscopic and miscible with water, acetone, and chloroform...
(C3H8O2)
- Calcium magnesium acetate
Calcium magnesium acetate is an alternative to road salt. It is approximately as corrosive as normal tap water, and in varying concentrations can be effective in stopping road ice from forming down to around .-External links:*...
(C4H6O2Ca and C4H6O2Mg)
- Sodium ferrocyanide
Sodium ferrocyanide, also known as tetrasodium hexacyanoferrate or sodium hexacyanoferrate , is a coordination compound of formula Na4Fe6 that forms semitransparent yellow crystals at room temperature and decomposes at its boiling point. It is soluble in water and insoluble in...
(hydrous, Na4Fe(CN)6•10H2O)
- Methyl alpha-D-glucopyranoside (C7H14O6)
SandSand is a naturally occurring granular material composed of finely divided rock and mineral particles.As the term is used by geologists, sand particles range in diameter from 0.0625 to 2 millimeters. An individual particle in this range size is termed a sand grain...
is also sometimes used to improve traction, though after the snow and ice has melted, sandy pavement has lower traction than sand-free pavement.
The choice of treatment may include consideration of the effect on vegetation, pets, the local
watershedA drainage basin is an extent of land where water from rain or snow melt drains downhill into a body of water, such as a river, lake, reservoir, estuary, wetland, sea or ocean...
, and effectiveness with regard to speed and temperature. Some chemicals can degrade
concreteConcrete is a construction material composed of cement as well as other cementitious materials such as fly ash and slag cement, aggregate , water, and chemical admixtures...
, metals, and other materials. The resulting
meltwaterMeltwater is the water released by the melting of snow or ice, including glacial ice and ice shelfs over oceans. Meltwater is often found in the ablation zone of glaciers, where the rate of snow cover is reducing...
and
slushSlush can mean any of the following:* Slush — a slurry mixture of liquid and solid forms of water.* Slush — a pejorative and slang combination of the likewise derogatory terms slut and lush...
can cause
frost heavingFrost heaving is the process by which the freezing of water-saturated soil causes the deformation and upward thrust of the ground surface. This process can damage plant roots through breaking or desiccation, cause cracks in pavement, and damage the foundations of buildings, even below the frost...
if it re-freezes, which can also damage pavement.
Snow removal tools
- Snow shovel
- Snow blower
Although the proper name is snow thrower, some people still use the name snow blower or snowblower. A snow thrower is a machine for removing snow from an area where it is not wanted, such as a driveway, sidewalk, roadway, railroad track or runway...
- Snowplow
A snowplow is a vehicle, or a device intended for mounting on a vehicle, for removing snow and sometimes ice from outdoor surfaces, typically those serving transportation purposes. In many cases, pickup trucks and tractors are outfitted with plows to fulfill this purpose...
- Ice pick or spade
A spade is a tool designed primarily for the purpose of digging or removing earth. The first spade was made of riven wood. After the art of metalworking was discovered, spades were made with sharper tips of metal. Before the advent of metal spades manual labor was less efficient at moving earth,...
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