WINTER SERVICE VEHICLE

A 'winter service vehicle' ('WSV'), also known as a 'snow removal unit' or 'snow removal vehicle', is a vehicle used to perform snow removal, the clearing of roads or other thoroughfares of ice or snow, which is difficult to cross and reduces the traction of motor vehicles.^[1] Winter service vehicles are usually based on dump truck chassis, with adaptations allowing them to carry specially designed snow removal equipment, although many authorities also keep a number of smaller vehicles for use on pavements, footpaths and cycleways. Road maintenance agencies and contractors in areas with temperate or polar climates often own multiple winter service vehicles in order to keep the road network clear of snow and ice and safe for driving during the winter months.^[2][3] Winter service vehicles are also employed by airports, in order to keep runways and taxiways free of snow and ice, which pose a danger to aircraft taking off and landing and can interfere with communication equipment.^[4]
The earliest winter service vehicles were snow rollers, designed to maintain a smooth, even road surface for sleds,^[5] although horse-drawn snowploughs and gritting vehicles are recorded in use as early as 1862.^[6] The increase in motor car traffic and aviation in the early 20th century lead to the development and popularisation of large motorised winter service vehicles. Today, most cities in areas prone to snow or ice operate fleets of winter service vehicles to keep roads and footpaths safe and clear.

Contents

History

Design

Operation

Equipment

De-icer

Gritter

Snow blower

Snow groomer

Snow melter

Snowplough

Snow sweeper

Surface friction tester

References

See also

Further reading

External links

Road snow removal

Airport snow removal

History

Although the concept of snow removal has existed since at least the Middle Ages, early attempts merely involved using a shovel or broom to remove the snow from walkways and roads. Before the invention of motorised transport, snow removal was seen as less of a concern: the unpaved roads present in rural areas were dangerous and bumpy; snow and ice made the surface far smoother. Most farmers could simply replace their wagons with sleds, allowing the transport of heavy materials such as timber with relative ease. Early communities in the northern regions of the United States and Canada even used animal-drawn snow rollers, the earliest winter service vehicles, to compress the snow covering roads. The compression increased the life of the snow and increased the ease of passage for sleds; some communities even employed snow wardens, whose job it was to spread or "pave" snow onto areas which were still exposed such as bridges to allow the sleds to use these routes.
However, with the increase in paved roads and the increasing size of cities, the process of snow-paving fell out of favour, as the smooth surfaces produced posed a danger to pedestrians and traffic. The earliest patents for snowploughs date back to 1840, but there are no records of their actual use until 1862, when the city of Milwaukee began operating horse-drawn carts fitted with snowploughs. The horse-drawn snowplough quickly spread to other cities, especially those in areas prone to heavy snowfall.
The first motorised snowploughs were developed in 1913, based on truck and tractor bodies, while the earliest snow blower, the Barber-Green snowloader, was invented in 1920. These machines allowed the mechanisation of the snow clearing process, reducing the labour required for snow removal and increasing the speed and efficiency of the process. The expansion of the aviation industry also acted as a catalyst for the development of winter service vehicles during the early 20th century. Even a light dusting of snow or ice could cause an aeroplane to crash, so large fences were erected around airfields to prevent snowdrifts forming and airports began to maintain fleets of winter service vehicles to keep the runways clear in heavy weather.
With the popularisation of the motor car, it was found that ploughing alone was insufficient for removing all snow and ice from the roadway, leading to the development of gritting vehicles, which used sodium chloride to accelerate the melting of the snow. Early attempts at gritting were resisted, as the salt used encouraged rusting, causing damage to the metal structures of bridges and the shoes of pedestrians. However, as the number of motoring accidents increased, the protests subsided and by 1925 many cities in the United States used salt and sand to improve clear the roads and increase road safety. As environmental awareness increased through the 1960s and 1970s, gritting once again fell out of favour as the environmental impact of grit was discovered, leading to the development of alternative de-icing chemicals and more efficient spreading systems.

Design

The cab of a winter service vehicle in Boston, Massachusetts, showing the plough-frame, amber lightbar and retroreflectors.

Winter service vehicles are usually based on dump truck chassis, which are then converted into winter service vehicles either by the manufacturer or an aftermarket third-party. A typical modification involves the replacement of steel components of the vehicle with corrosion resistant aluminium or fibreglass, waterproofing any exposed electronic components, replacement of the stock hopper with a specially designed gritting body, the addition of a plough frame, reinforcement of the bumpers to support the heavy blade, and the addition of extra headlamps, a light bar and retroreflectors for visibility.^[8] Other common changes include the replacement of the stock tyres with rain tyres or mud and snow tyres and the shortening of the vehicle's wheelbase to improve manoeuvrability.^[9] However, some winter service vehicles, especially those designed for use on footpaths or pedestrianised zones, are built on a far smaller chassis. These vehicles are often multi-purpose, and can be fitted with other equipment such as brushes, lawnmowers or cranes, allowing the vehicles to be used even in warm or dry weather and reducing the size of the fleet required by the agency or contractor.^[10] Modern winter service vehicles will usually also have a satellite navigation system connected to a weather forecast feed, allowing the driver to choose the best areas to treat and to avoid areas in which rain is likely, which can wash away the grit used. Military winter service vehicles are heavily armoured to allow for their use in combat zones, especially in Arctic and mountain warfare, and often based on combat bulldozers or HMMWVs.^[11] Military winter service vehicles have been used by the United Nations, Kosovo Force and the U.S. Army in Central Europe during the Kosovo War,^[12] while during the Cold War, the Royal Marines and Royal Corps of Signals deployed a number of tracked vehicles in Norway to patrol the NATO border with the Soviet Union.^[13][14]
Most winter service vehicles run on wheels, often with snow chains or studded tyres, but some are mounted on caterpillar tracks, with the tracks themselves adapted to throw the snow towards the side of the road.^[15] Off-road winter service vehicles mounted on caterpillar tracks are known as snowcats. Snowcats are commonly fitted with snowploughs or snow groomers, and are used by ski resorts to smooth and maintain pistes and snowmobile runs, although they can also be used as a replacement for chairlifts.^[16]
In most countries, winter service vehicles usually have amber light bars, which are activated to indicate that the vehicle is operating below the local speed limit or otherwise poses a danger to other traffic, either by straddling multiple lanes or by spreading grit or de-icer. In some areas, such as the Canadian province of Ontario, winter service vehicles use the blue flashing lights associated with emergency service vehicles, rather than the amber or orange used elsewhere.^[17] Many agencies also paint their vehicles in high-contrast orange or yellow to allow the vehicles to been seen more clearly in whiteout conditions.

Operation

A salt barn near Lake Michigan, used for storing grit and providing limited accommodation for gritter drivers during winter storms.

Winter service vehicles are operated by both government agencies and by private subcontractors. Public works in areas which regularly receive snowfall usually maintain a fleet of their own vehicles or pay retainers to contractors for priority access to vehicles in winter, while cities where snow is a less regular occurrence may simply hire the vehicles as needed.^[18] Winter service vehicles in the United Kingdom are the only road-going vehicles entitled to use red diesel. Though the vehicles still use public highways, they are used to keep the road network operational, and forcing them to pay extra tax to do so would discourage private contractors from assisting with snow removal on public roads.^[19] Winter service vehicle drivers in the United States must hold a Class B or Class A commercial driver's license,^[20] while in the European Union, drivers must have a Category C Large Goods Vehicle licence.^[21] Although some agencies in some areas, such as the U.S. state of Minnesota, allow winter service vehicle drivers to operate without any extra training,^[22] most provide supplemental lessons to drivers in order to teach them the most effective and safe methods of snow removal. Many require that trainee drivers ride-along with more experienced drivers, and some even operate specially designed driving simulators, which can safely replicate dangerous winter driving conditions.

A brine tank at a service depot in Germany.

Winter service vehicle drivers usually work part time, before and during inclement weather only, with drivers working a 12 to 16 hour shift.^[23] Main roads are typically gritted in advance, in order to reduce the disruption to the network. Salt barns are provided at regular intervals for drivers to collect more grit, and bedding is provided at road maintenance depots for drivers to use between shifts in heavy or prolonged storms.
Weather conditions typically vary greatly depending on altitude; hot countries can experience heavy snowfall in mountainous regions yet receive very little in low-lying areas, increasing the accident rate among drivers inexperienced in winter driving. In addition, road surface temperatures can fall rapidly at higher altitudes, precipitating rapid frost formation. As a result, gritting and ploughing runs are often prioritised in favour of clearing these mountain roads, especially at the start and end of the snow season.^[24] The hazardous roads through mountain passes pose additional problems for the large winter service vehicles. The heavy metal frame and bulky grit makes hill climbing demanding for the vehicle, so vehicles have extremely high torque transmission systems to provide enough power to make the climb. Furthermore, while the tight hairpin turns found on mountain slopes are difficult for long vehicles to navigate, winter service vehicles for use in mountainous areas are shortened, usually from six wheels to four.

Equipment

De-icer

Main articles: de-icing

A de-icing vehicle treating an American Airlines MD-80 at Syracuse Hancock International Airport, New York.

De-icers spray heated de-icing fluid, often propylene glycol or ethylene glycol, onto icy surfaces such as the bodies of aircraft and road surfaces.^[25] These prevent ice from forming on the body of the aircraft while on the ground. Ice makes the surface of the wings rougher, reducing the amount of lift they provide while increasing drag. The ice also increases the weight of the aircraft and can affect its balance.
Aircraft de-icing vehicles usually consist of a large tanker truck, containing the concentrated de-icing fluid, with a water feed to dilute the fluid according to the ambient temperature. The vehicle also normally has a cherry picker crane, allowing the operator to spray the entire aircraft in as little time as possible; an entire Boeing 737 can be treated in under 10 minutes by a single de-icing vehicle.
Some road contractors also choose to use de-icers as an alternative to gritters; the vehicle carries a tank of brine, which is sprayed on the road surface. Brine acts faster than solid salt and does not require compression by passing traffic to become effective. The brine is also more environmentally friendly, as less salt is required to treat the same length of road.^[26] Airport runways are also de-iced by sprayers fitted with long spraying arms. These arms are wide enough to cross the entire runway, and allow de-icing of the entire airstrip to take place in a single pass, reducing the length of time that the runway is unavailable.^[27]

Gritter

The hopper and impeller of a gritter in Germany.

A gritter, also known as a sander,^[28] salt spreader or salt truck, is found on most winter service vehicles. Indeed, the gritter is so commonly seen on winter service vehicles that the terms are sometimes used synonymously. Gritters are used to spread grit, a mixture of sand and rock salt, onto roads. The grit is stored in the large hopper on the rear of the vehicle, and spread across the roadway by an impeller. Salt reduces the melting point of ice by freezing-point depression, causing it to melt at lower temperatures and run off harmlessly to the edge of the road, while sand increases traction by increasing friction between car tyres and roadways. The amount of salt dropped varies with the condition of the road; to prevent the formation of light ice, approximately 10 grams per square metre (0.3 oz/yd²) is dropped, while thick snow can require up to 40 g/m² (1.2 oz/yd²) of salt, independent of the volume of sand dropped.^[29] The grit is sometimes mixed with molasses to help adhesion to the road surface. However, the sweet molasses often attracts livestock, who lick the road and can become addicted to the sugar.^[30] The grit is sometimes heated as it is passed out of the nozzle; this helps melt the ice and improves the solubility of the salt. Quieter rural roads may be considered too minor to grit, so grit bins are often provided, containing a mixture of sand and salt for drivers and pedestrians to shovel onto the road themselves.
Gritters are among the winter service vehicles also used in airports, to keep runways free of ice. However, the salt normally used to clear roads can damage the airframe of aircraft and interferes with the sensitive navigation equipment. As a result, airport gritters spread less dangerous potassium acetate onto the runways instead, as potassium acetate does not corrode the aircraft or the airside equipment.
The salt dropped by gritters comes from a non-renewable source, and high concentrations of salt in soil kill plants, so it is in the interest of operators to limit gritting to an absolute minimum. As a result, road maintenance agencies have advanced networks of ice prediction stations, to prevent unnecessary gritting which not only wastes salt, but can damage the environment and disrupt traffic.^[31][32] The salt dropped is eventually washed away and lost, so it cannot be reused or collected after gritting runs, although the insoluble sand can be collected and recycled by street sweeping vehicles and mixed with new salt crystals to be reused in later batches of grit.^[33] As a result, operators must regularly purchase large quantities of rock salt, depleting a finite resource and damaging the environment through dangerous and polluting salt mining.^[34] In some areas of the world, including Berlin, dropping salt is prohibited altogether, except on the highest-risk roads; plain sand, without any melting agents, is spread instead. Although this protects the environment, it is more labour-intensive, as more gritting runs are needed; and as the sand is insoluble, it tends to accumulate at the sides of the road, making it more difficult for buses to pull in at bus stops.^[35] Other areas use alternative chemicals which are less harmful to the environment and cause less corrosion damage to metallic structures. The U.S. state of Oregon uses magnesium chloride, a relatively cheap chemical similar in molecular structure to sodium chloride, but less reactive,^[36] while New Zealand uses calcium magnesium acetate, which avoids the environmentally harmful chloride ion altogether.^[37] Gritting vehicles are also dangerous to overtake; as grit is scattered across the entire roadway, loose pieces can damage the paintwork and windows of passing cars, and the loose salt does not provide sufficient traction for motorcycles, which can lead to skiding, especially around corners.
Gritters can also be used in hot weather, when temperatures are high enough to melt the bitumen used in asphalt. The grit is dropped to provide a protective layer between the road surface and the tyres of passing vehicles, which would otherwise damage the road surface by "plucking out" the bitumen-coated aggregate from the road surface.^[38]

Snow blower

Main articles: snow blower

A Zaugg snow blower fitted with snow chains in Germany.

Snow blowers, also known as rotating snowploughs or snow cutters,^[39] can be used in place of snowploughs on winter service vehicles. A snow blower consists of a rapidly spinning blade which cuts through the snow, forcing it out of a funnel attached to the top of the blower. Snow blowers typically clear much faster than ploughs, with some clearing in excess of 5000 tonnes of snow per hour, and can cut through far deeper snow drifts than a snowplough can.^[40] In addition, snow blowers can remove snow from the roadway completely, rather than piling it at the side of the road, making passage easier for other road users and preventing the windrow from blocking driveways.^[41] However, snow blowing is an energy intensive and environmentally unfriendly process, producing higher levels of air pollution and noise pollution than other methods of snow removal.^[42]

Snow groomer

Main articles: snow grooming

A modern snow groomer mounted to the rear of a snowcat in Hautes-Pyrénées, France.

A snow groomer is a machine designed to smooth and compact the snow, rather than removing it altogether. Early snow groomers were used by residents of rural areas to compress the snow close to their homes,^[43] and consisted of a heavy roller hauled by oxen which compacted the snow to make a smooth surface for sledging. With the invention of the motor car, snow groomers were replaced by snowploughs and snow blowers on public thoroughfares, but remained in use at ski resorts, where they are used to maintain smooth, safe trails for various wintersports, including skiing, snowboarding and snowmobiling. Snow groomers remained unchanged throughout the 20th century, with most consisting of heavy roller which could be attached to a tractor or snowcat and then hauled across the area to be groomed.^[44]
With the development of more advanced electronic systems in the 1980s allowed manufacturers to produce snow groomers which could work on and replicate a much wider range of terrains, with the most modern even able to produce half-pipes and ramps for snowboarding. Snow groomers are also used in conjunction with snow cannons, in order to ensure that the snow produced is spread evenly across the resort.^[45] However, snow groomers have a detrimental effect on the environment within the resort. Grooming removes nutrients and minerals from the soil underneath the snow and the regular pressure from the grooming vehicle increases the infiltration rate of the soil while decreasing the field capacity. This increases the rate at which water can soak through the soil, making it more prone to erosion.^[46]

Snow melter

Snow melters working at JFK Airport, New York.

A snow melting vehicle works by scooping snow into a melting pit located in a large tank at the rear of the vehicle. Around the melting pit is a smaller tank full of boiling water, heated by a powerful burner. The gases from the burner are bubbled through the water, causing some of the water to spill over into the melting pit, melting the snow instantly. The meltwater is discharged into the storm drains.^[47]
As they have to carry the large water tank and fuel for the burner, snow melting machines tend to be much larger and heavier than most winter service vehicles, at around , with the largest being hauled by semi-trailer tractor units.^[48] In addition, the complicated melting process means that snow melting vehicles have a much lower capacity than the equivalent plough or blower vehicle; the largest snow melter can remove 500 tonnes of snow per hour, compared to the 5000 tonnes per hour capacity of any large snow blower. However, snow melters are far more environmentally friendly than gritters, as they do not spray hazardous materials, and pollutants from the road surface can be separated from the meltwater and disposed of safely. In addition, as the snow is melted on board, the costs of removing the collected snow from the site is removed.^[49]

Snowplough

Main articles: snowplough

A German snowplough with a hopper for carrying grit.

Many winter service vehicles can be fitted with snowploughs, in order to clear roads which are blocked by deep snow. Most winter service vehicles include either permanently fixed ploughs or plough frames: 75% of the UK's Highways Agency vehicles include a plough frame to which a blade can be attached. In most cases, the ploughs are mounted on hydraulically-actuated arms, allowing them to be raised, lowered, and angled to better move snow. In the event that specially designed winter service vehicles are not available for ploughing, other service or construction vehicles can be used instead: among those used by various authorities are graders, bulldozers,^[50] skid loaders,^[51] and rubbish trucks.^[52] Front-end loaders can also be used to plough snow. Either a snowplough attachment mounts on the loader's arm in place of the bucket, or their bucket or snowbasket loads snow into the rear compartment of a snowplough or dump truck, which then hauls it away.^[15] Snowploughs are dangerous to overtake; often, the oncoming lane may not be completely free of snow. In addition, the plough blade causes considerable spray of snow on both sides, which can obscure the vision of other road users.

Snow sweeper

A snow sweeper uses brushes, similar to those seen on street sweepers, to remove thin layers of snow from the pavement surface. Snow sweepers are used after ploughing in order to remove any remaining material missed by the larger vehicles in areas with very low snow-tolerance, such as airport runways and racing tracks,^[54] and the flexible brushes follow the terrain better than the rigid blades of snowploughs and snow blowers.^[55] Unlike other winter service vehicles, snow sweepers do not compress the snow, leaving a rougher, higher friction, surface behind them, making snow sweepers the most efficient method of snow removal for snow depths below 10 centimetres (4 in).^[56] Snow deeper than this however can clog the brushes, and most snow sweepers cannot be used to clear snow deeper than 15 centimetres (6 in). A more advanced version of the snow sweeper is the jet sweeper, which adds an air-blower just behind the brushes, in order to blow the swept snow clear of the pavement and prevent the loosened snow from settling.

Surface friction tester

The surface friction tester is a small fifth wheel attached to a hydraulic system mounted on the rear axle of the vehicle, canted slightly relative to the ground, generally used at airports and on major roadways before ice formation.^[57] The wheel is allowed to turn freely, allowing sensors attached to the axis of the wheel to calculate the friction between the wheel and the driving surface by the measuring the torque produced by the rotation of the wheel. The vehicle can relay the surface friction data back to the control centre, allowing gritting and clearing routes to be planned so that the vehicles are deployed most efficiently.^[58] Surface friction testers often include a water spraying system, in order to simulate the effects of rain on the road surface before the rain occurs. The sensors are usually mounted to small compact or estate cars or to a small trailer, rather than the large trucks used for other winter service equipment, as the surface friction tester works best when attached to lightweight vehicles.^[59][60]

References

1. Winter Driving
2. Report on the 1998 scanning review of European winter service technology, United States National Research Council, , , Transportation Research Board, 1999,
3. Winter Maintenance Technology and Practices - Learning from Abroad, United States National Research Council, , , Transportation Research Board, ,
4. Once around the world: Dresden Airport's Winter Service covered about 40,000 km .
5. Moving The Snow
6. Have Snow Shovel, Will Travel
7. Ein Fest für Pferdefreunde
8. Gritting Contractors : History Of Gritting
9. Gritting Contractors : Vehicles
10. Flexible applications
11. High Mobility Multipurpose Wheeled Vehicle Snowplow
12. Snow and Ice Control (SNIC) Equipment and Its Use by Military Units Worldwide
13. Aktiv Snow-Trac Info
14. United Nations and NATO Peace Keeping
15.
16.
17. Ontario Highway Traffic Act R.S.O. 1990, CHAPTER H.8 section 62-31
18. City may ante up to ensure snow plowing
19.
20. Learning to drive a snowplow
21. MAC Model Contract
22. Dream Job: Snowplow Driver
23. How do snowplough drivers get to work?
24. Sixth International Symposium on Snow Removal and Ice Control, , , , , ,
25. Winter service team at Dresden Airport ready for the cold season
26. Gritty Gritty Bang Bang! Ann-Marie Kengt
27. Airside nozzle sprayers
28. Cambridge Dictionary definition: Gritter
29. Highway Winter Maintenance: ICE Design and Practice Guide, , , , Thomas Telford, 2000,
30. New road grit popular - with sheep
31. New facilities help guard against winter
32. Winter Highway Gritting
33. Street Department
34. Minerals Local Plan - Chapter 9
35. Highway Meteorology, , , , Spon Press, ,
36. Winter Road Maintenance Practices
37. Sixth International Symposium on Snow Removal and Ice Control, , , , , ,
38. Gritters to combat melting roads
39. Attachable snow clearing
40. Supra 5001 specification
41. What is a snowblower?
42. Best Inventions of 2006
43. Snow Removal Equipment Changes Over Time Wayne Carhart
44. Classic New Hampshire: Preserving the Granite State in Changing Times, , Linda, Landry, University Press of New England, 2003,
45. How Snow Makers Work
46. Nature-Based Tourism, Environment, and Land Management, , Ralph, Buckley, CAB International, ,
47. Principle of Operation
48. 500-PD specifications
49. Economics of Snow Melting
50. Transportation Division - Snow Operations
51. Washington and Jefferson College snow response plan
52. Sanitation to begin winter night plow schedule
53.
54. Jet sweeper
55. Snow Sweeper
56. Snow sweepers
57. MK IV rear axle system
58. Aircraft De-icing
59. ASFT VW Sharan Road Surface Friction Tester
60. ASFT T-10 Trailer Road Surface Friction Tester

See also

★ Cesspool emptier

★ Emergency vehicle

★ Engineering vehicle

★ Gully emptier

★ Street sweeper

★ Waste collection vehicle

Further reading

★ Handbook of Snow: Principles, Processes, Management and Use, , Donald, Gray, Pergamon, 1981,

★ Chemical Deicers and the Environment, , Frank M., D'Itri, CRC Press, 1992,

★ Snow in the Cities: A History of America's Urban Response, , Blake, McKelvey, University of Rochester Press, ,

★ Snow Engineering: Recent Advances, , Ronald L., Sack, Taylor & Francis, 1997,

★ Snow and Ice Control Manual for Transportation Facilities, , L. David, Minsk, McGraw Hill, 1998,

★

★ Snow and Ice Control: Guidelines for Materials and Methods, , Robert R., Blackburn, Transportation Research Board, 2004,

★ Winter Highway Operations, , Steven M., Conger, Transportation Research Board, 2005,

External links

★ Snow removal site links — National Snow and Ice Data Center

Road snow removal

★ Master Plan for Snow and Ice Control — City of Sapporo

★ Driving in adverse weather conditions — The Highway Code

★ Winter Service — The Highways Agency

★ International Winter Roads Congress

★ Snow Removal and Snow Driving — Virginia Department of Transportation

Airport snow removal

★ Winter services at Dresden Airport — Dresden Airport

★ Snow & Ice Control Procedures — St. Louis Downtown Airport

★ Snow clearance at Vnukovo International Airport — Vnukovo International Airport