Snow removal
Snow removal or snow clearing is the job of removing snow after a snowfall to make travel easier and safer. This is done both by individual households and by governments institutions, and commercial businesses.
De-icing and anti-icing
De-icing is defined as removal of existing snow, ice or frost from a roadway, airport runway, roof, or other surface. It includes both mechanical means, such as plowing, vacuuming or scraping, and chemical means, such as application of salt or other ice-melting chemicals. Anti-icing is treatment with ice-melting chemicals before or during the onset of a storm in order to prevent or delay the formation and adhesion of ice and snow to the surface. Brine, or wetted salt, is usually applied shortly before the beginning of a snowstorm. When properly performed, anti-icing can significantly reduce the amount of salt required and allow easier removal by mechanical methods, including plowing.The de-icing of roads has historically been accomplished by snowplows or specially designed dump trucks that spread salt, often mixed with sand and gravel, onto slick roads. Rock salt is normally used because it is inexpensive and readily available in large quantities. However, brine freezes at −18 °C, and so it is ineffective at these low temperatures. It also has a strong tendency to cause corrosion, rusting the steel used in most vehicles and the rebar in concrete bridges. More recent snowmelters use other salts, such as calcium chloride and magnesium chloride, which not only decrease the freezing point of water to a much lower temperature but also produce an exothermic reaction, whose dissipated heat further aids in melting. In addition, they are somewhat safer for concrete sidewalks, but excess should still be removed.
Recently, organic compounds have been developed that reduce the environmental impact associated with salts and that have longer residual effects when spread on roadways, usually in conjunction with salt brines or solids. These compounds are generated as byproducts of agricultural operations, such as sugar beet refining or ethanol distillation. A mixture of some selection of these organic compounds with a combination of salts results in a substance that is both more easily spread and more effective at lower temperatures.
Since the 1990s, use of liquid chemical melters has been increasing, sprayed on roads by nozzles instead of a spinning spreader used with salts. Liquid melters are more effective at preventing the ice from bonding to the surface than melting through existing ice.
Several proprietary products incorporate anti-icing chemicals into the pavement. Verglimit incorporates calcium chloride granules into asphalt pavement. The granules are continually exposed by traffic wear, and release calcium chloride onto the surface. This prevents snow and ice from sticking to the pavement
Cargill SafeLane is a proprietary pavement surface treatment that absorbs anti-icing brines, to be released during a storm or other icing event. It also provides a high-friction surface, increasing traction.
In Niigata, Japan, relatively inexpensive hot water bubbles up through holes in the pavement to melt snow, though this solution is only practical within a city or town. Some individual buildings may melt snow and ice with electric heating elements buried in the pavement, or even on a roof to prevent ice dams on the shingles, or to keep massive chunks of snow and dangerous icicles from collapsing on anyone below. Small areas of pavement can be kept ice-free by circulating heated liquids in embedded piping systems.
Clearing by individuals
Most snow removal by individuals is clearance of driveways and walkways. After heavy snowfalls, snow may be removed from roofs to reduce the risk of structural damage due to the weight.In places with light snow, brooms or other light instruments can be used to brush off snow from walks and other surfaces. In regions with more precipitation, snow is commonly removed with snow shovels, a large lightweight shovel used to push snow and lift it, and snow scoops or sleigh shovels, 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. Other tools include snow pushers and shovels with one or more wheels.
Compared to other tasks of equal importance, snow removal can present unusual age dynamics pertaining to overall community safety and efficient cooperation of skills. The relatively simple act of manual snow shoveling is statistically safer for teenagers than for adults, safer for boys than for men, and safer for children than for senior citizens. Shovelling entails a considerable amount of physical effort and can strain the back and the heart for those who lack good physical health, have heart problems, or who are largely sedentary. Each year many seniors and middle aged persons die from heart attacks while shovelling snow.
Snow blowers are often used by people unwilling or unable to perform this labour, people with large driveways or other substantial surfaces and people who 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.
Removing ice is more difficult. Snow blowers are usually ineffective at clearing ice. Picks are sometimes used, but a solid spade can break through most ice. There is always the risk of damaging the pavement with these instruments. Icy areas can be covered with salt or some other substance, bags of which are widely available.
A recent technological advance is the snowmelt system 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, Boy Scout troops, and adult volunteer agencies offer free snow clearing for the elderly and others in need. In some cities, snow clearing for elder and handicapped residents counts towards community service hours assigned as a punishment for minor offences.
In many places, laws require homeowners to clear snow from the public sidewalk in front of their house, as well as a pathway on their own property to their mailbox. Traditionally, this creates a unique opportunity for neighborhood youth to make legitimate money. Homeowners who fail to clear sidewalks, depending on the jurisdiction's laws, may experience fines and may be civilly liable for injuries suffered by another on a surface that they were required to clear. In some jurisdictions, such as New York, even private home owners who do clear their pathways can be held civilly liable for others' injuries incurred by falling in areas that have been cleared.
Cleaning off and freeing one's vehicle is another matter. Some people who need their vehicles will only do barely what is necessary in order to drive the vehicle and remove it from its space. Failure to clear all the snow and ice from a vehicle causes hazards by impairing the driver's visibility, and ice from the roofs of driven vehicles can cause crashes. In some jurisdictions, motorists who fail to clear snow from their vehicle entirely may be fined. Others may be more thorough in this process.
In some urban residential areas with curbside parking, residents use objects to mark the spaces they dug out so they can reclaim their space upon their return.
A leaf blower is sometimes used to blow light powder snow from vehicles, driveways, walkways, and decks. This only works well for very light powder snow.
Clearing by the owners of contiguous lands or buildings
In some countries, keeping sidewalks clear and safe in winter is a duty of the owner of the contiguous land or building. The owner can be an individual inhabitant, in case of a family house, but also the municipality, municipal district or their specific organization or a housing co-operative or some other company. Owners of large buildings or building complexes generally have mechanized snow-removal equipment, but individual house owners mostly clean the sidewalk with hand tools.One example of the longstanding debate over the obligation of snow removal comes from the Czech Republic. In Prague, evidence of such a duty is documented since 1838. The decree of the government of the Protectorate of Bohemia and Moravia No. 1/1943 Sb. said that sidewalk cleaning in residential areas of municipalities with more than 5000 inhabitants, of district cities and of other specified municipalities is a duty of the owner or user of the contiguous land. The municipality was empowered to undertake this duty at the expense of the contiguous land owner. The Czechoslovak Road Act No. 135/1961 Sb. adopted such legal regulations for all municipalities, but municipality offices could modify them. The new Road Act of the Czech Republic, No. 13/1997 Sb. left this enactment in place and stated that maintenance of a road, path, track etc. is an obligation of its owner without any exception. Despite this, §27 art. 4 attached to the owner of contiguous land the liability for harm caused by defects of cleaning. In its 2002 and 2003 annual reports, the Czech Public Defender of Rights made a claim for there being a discrepancy between the theoretical and the practical interpretations of the act and recommended that an unequivocal formulation be enacted. This discrepancy was repeatedly handled by the courts, and the Supreme Administrative Court on 27 June 2005 and the Constitutional Court on 3 January 2007 each stated that the cleaning duty results indirectly from the stated liability for harm. Those who impugn the duty argued that it is a residue of feudal corvée or of the totalitarian Nazi and communist regimes, that nowadays, compulsory labour mandated by law is in conflict with the Charter of Fundamental Rights and Basic Freedoms and that systematic municipal cleaning is more effective than cleaning by individuals. On 6 December 2007, the Senate of the Czech Republic proposed at the instance of its Constitutional Committee to remove the controversial article from §27 of the Road Act of 1997. The Czech Government gave support to it by a narrow majority. In a previous vote and after heated debate, the Chamber of Deputies of the Czech Republic had sanctioned this change by a margin of 116 to 31 amongst the 190 members present. Since 16 April 2009, the changes made by Act No. 97/2009 Sb. mandate that sidewalk cleaning is an obligation only of the owner of the walkway or road, i.e. generally the municipality. Despite the abolition of the duty, many people, including its opponents, declared that they will continue the winter cleaning of municipal sidewalks and paths, but instead will do so voluntarily and on their own behalf.
As was mentioned during the discussion in the Czech Parliament in a statement by the Czech Association of Cities and Municipalities, a similar duty belongs to owners of contiguous land exists in many other modern countries, e.g. Austria, France, the United States and some cities in Bavaria.