An ice road or ice bridge [1] [2] [3] [4] is a human-made structure that runs on a frozen water surface (a river, a lake or a sea water expanse). [5] [6] [7] Ice roads are typically part of a winter road, but they can also be simple stand-alone structures, connecting two shorelines. [8] [9] Ice roads may be planned, built and maintained so as to remain safe and effective, and a number of guidelines have been published with information in these regards. [1] [4] [10] [11] An ice road may be constructed year after year, for instance to service community needs during the winter. [4] [12] It could also be for a single year or two, so as to supply particular operations, such as a hydroelectric project [13] or offshore drill sites. [14]
The ability of an ice road to safely support the weight of a vehicle (or any other loads applied onto it), referred to as bearing capacity, is the primary concern when designing, building and using that structure. Generally speaking, a vertically loaded ice cover will react in two ways: 1) it will sink, and 2) it will bend in flexure. [1] [5] In order to meet the ice bearing criteria, the top surface should not sink below the water line and the applied flexural stress should not exceed the ice's flexural strength. [15] Three loading regimes have to be considered: a) maximum weight for standard usage or for parking during a short duration; b) a load that remains stationary during an extensive time period; and c) dynamic loading of the ice cover, from a traveling vehicle.
For standard traffic activities, guidelines typically use a simple empirical formula to determine the maximum vehicle weight that should be allowed on an ice road. [11] [16] This formula, which was initially proposed in 1971, [17] is often referred to as Gold's formula:
where P is the load, h is the thickness and A is a constant with a unit of pressure. It may be linked with an idealized elastic response of the ice cover: [1]
where σmax is the maximum tensile strength at the bottom of an infinite ice plate resting on an elastic foundation. The parameter C is based on the theory of thick plates. Hence, with this idealized formulation, A is representative of the ice cover tensile strength. Although recommended values for A range from 3.5 to 10 kg/cm2 (~ 50–150 lbs/in2), lower bound values are generally those that are used for safety purposes. [11] [16] This level of conservatism is justified because, unlike human-made materials such as steel or concrete, natural ice covers inherently contain a large amount of structural flaws (fractures, water and air pockets). [2] Moreover, for a public road, which is relatively uncontrolled, such an approach introduces a high safety factor against breakthroughs and is therefore desirable. For industrial roads, the design may be less conservative so as to handle their functional requirements, i.e. higher A values can be used, but under the close supervision of a professional engineer. [4] [2]
When using Gold's formula, a purely elastic response is assumed, which is, by definition, instantaneous and independent of loading time. Ice, however, naturally exists at a high homologous temperature, i.e. near its melting point. As is the case for any other material under these conditions, response to loading is not only elastic, but incorporates other components, namely: [18] [19]
Thus, an ice cover may be able to safely support a vehicle, but if it remains on the ice for too long, deformation will continue via microcracking, leading to the collapse of the ice cover below the vehicle. Recommendations vary as to how this can be avoided. [11] [16] Some sources prescribe a maximum of two hours for a stationary load, [20] [3] [4] which is also what Gold recommended. [17] Others advise to use the freeboard of the ice as an indicator, [18] [1] [2] [3] which can be done by drilling a hole in it and monitoring the distance between the water in the hole and the ice surface. The vehicle should be removed before the water reaches the surface in that hole. Another reason why the amount of freeboard matters is that if the water makes its way onto the ice surface (through cracks and fissures), the ice cover's bearing capacity diminishes rapidly, which can accelerate breakthrough. [15] [1] For long-term loads, a professional engineer may have to be consulted. [4]
As a vehicle travels on the road, a dynamic loading regime is exerted onto the ice cover. [1] [4] Below a specific speed, referred to as critical, the ice cover beneath the vehicle will assume the shape of a bowl moving with the vehicle, pushing away the water around it, as the keel of a boat does. [1] At (and above) the critical speed, a series of waves will form behind and in front of the vehicle. "If the celerity of these waves is the same as the vehicle speed, the deflection and the stresses in the ice sheet are amplified, similar to resonance in an oscillating system" (pp. 8–10). [1] The critical speed depends on ice thickness and water depth. Another issue that arises is the reflection of these waves from the shoreline back toward the vehicle. This can induce additional stresses on the ice – one way to mitigate this issue is to avoid approaching shorelines at 90 degrees. [4] The critical speed is what determines the speed limit for vehicles traveling on ice roads. That limit can be as low as 10 km/h (6.2 mph) to 35 km/h (22 mph). [3] [4] Dynamic loading of the ice cover may also dictate a minimum distance between vehicles. [4] [2]
The effects of dynamic loading on a floating ice sheet has been investigated via field testing. [22] [23] [24] The most compelling evidence of such wave patterns, however, was captured by satellite imagery. [25] [21]
When an ice road is part of a winter road, as is commonly the case, its design and construction is comprised within the overall road planning, i.e. in conjunction with the over-land segments. [2] Either way, factors that need to be addressed before construction include the following:
Factors that need to be considered in route selection include the following: [2] [3] [12]
Before first access to the ice, the following factors need to be considered: [2] [4] [3]
Snow cover removal is the first major operation in an ice road construction scheme. [2] [3] [12] [26] It may only begin once the ice thickness is safe to support the machinery used for that operation. There are two ways of doing it, depending on available equipment and state of practice for that particular road. One is to pack the snow layer with tracked vehicles into a thin layer, thereby increasing its density and reducing its insulating properties. The other is to remove it altogether, typically with vehicles fitted with a snowplow.
Once the ice has reached the target thickness (via accelerated growth after removing the insulating effects of the snow), road construction per se may commence. At that point, the ice is able to safely support the heavier equipment required for that phase, which mostly consists of artificial thickening using a pump or a spraying system. [2] [5] The aim is to bring the thickness up to what is required for the heaviest vehicles that are anticipated when the ice road opens.
Vehicles traveling on an ice road include ordinary automobiles and trucks of various sizes and weights. Standard winter tires are sufficient, i.e. cleats and tire chains can damage the road surface. [12] [26] However, tire chains may be stored in the vehicle for emergency purposes; [2] [4] they can also come in handy when traveling on a winter road with grades steeper than 8% on over-land segments. [2] Signage may indicate speed limits, for instance a maximum of 25 km/h (16 mph), and spacing between vehicles, for instance 500 m (1,600 ft) for loads more than 12,500 kg (27,600 lb). [2] [4] These restrictions are to decrease the risks of damage to the ice cover, which would compromise its ability to support the weight it has been designed for.
Maintenance comprises two main tasks: [3] [4] [2] [12]
An ice road will typically be closed as a result of deterioration of the running or operating surface, before there is any risk of ice cover failure. [4] Surface deterioration can happen when the ice surface becomes too soft, or because of an excessive amount of meltwater on its surface. [3] [26] Mid-season road closures can also happen for similar reasons, and also because of inclement weather, such as a blizzard. [3] [12] If the ice road is part of a winter road, then closure can also be due to an over-land segment that has become unserviceable.
Ice crossings can be made to support higher loads if they are reinforced, and there are a number of ways this has been done in the past. [27] [28] [29] Also, because these structures are vulnerable to a warming climate, which reduces their operational lifespan, [30] [31] they may benefit from reinforcement along problematic segments, such as creek crossings and where the winter road crosses a shoreline.
Transport in Antarctica has transformed from explorers crossing the isolated remote area of Antarctica by foot to a more open era due to human technologies enabling more convenient and faster transport, predominantly by air and water, but also by land as well. Transportation technologies on a remote area like Antarctica need to be able to deal with extremely low temperatures and continuous winds to ensure the travelers' safety. Due to the fragility of the Antarctic environment, only a limited amount of transport movements can take place and sustainable transportation technologies have to be used to reduce the ecological footprint. The infrastructure of land, water and air transport needs to be safe and sustainable. Currently thousands of tourists and hundreds of scientists a year depend on the Antarctic transportation system.
Ice is water that is frozen into a solid state, typically forming at or below temperatures of 0 °C, 32 °F, or 273.15 K. It occurs naturally on Earth, on other planets, in Oort cloud objects, and as interstellar ice. As a naturally occurring crystalline inorganic solid with an ordered structure, ice is considered to be a mineral. Depending on the presence of impurities such as particles of soil or bubbles of air, it can appear transparent or a more or less opaque bluish-white color.
Snow comprises individual ice crystals that grow while suspended in the atmosphere—usually within clouds—and then fall, accumulating on the ground where they undergo further changes. It consists of frozen crystalline water throughout its life cycle, starting when, under suitable conditions, the ice crystals form in the atmosphere, increase to millimeter size, precipitate and accumulate on surfaces, then metamorphose in place, and ultimately melt, slide or sublimate away.
Road transport or road transportation is a type of transport using roads. Transport on roads can be roughly grouped into the transportation of goods and transportation of people. In many countries licensing requirements and safety regulations ensure a separation of the two industries. Movement along roads may be by bike, automobile, bus, truck, or by animal such as horse or oxen. Standard networks of roads were adopted by Romans, Persians, Aztec, and other early empires, and may be regarded as a feature of empires. Cargo may be transported by trucking companies, while passengers may be transported via mass transit. Commonly defined features of modern roads include defined lanes and signage. Various classes of road exist, from two-lane local roads with at-grade intersections to controlled-access highways with all cross traffic grade-separated.
A tire is a ring-shaped component that surrounds a wheel's rim to transfer a vehicle's load from the axle through the wheel to the ground and to provide traction on the surface over which the wheel travels. Most tires, such as those for automobiles and bicycles, are pneumatically inflated structures, providing a flexible cushion that absorbs shock as the tire rolls over rough features on the surface. Tires provide a footprint, called a contact patch, designed to match the vehicle's weight and the bearing on the surface that it rolls over by exerting a pressure that will avoid deforming the surface.
Muskeg is a peat-forming ecosystem found in several northern climates, most commonly in Arctic and boreal areas. Muskeg is approximately synonymous with bog or peatland, and is a standard term in Canada and Alaska. The term became common in these areas because it is of Cree origin; maskek (ᒪᐢᑫᐠ) meaning "low-lying marsh".
Highway engineering is a professional engineering discipline branching from the civil engineering subdiscipline of transportation engineering that involves the planning, design, construction, operation, and maintenance of roads, highways, streets, bridges, and tunnels to ensure safe and effective transportation of people and goods. Highway engineering became prominent towards the latter half of the 20th century after World War II. Standards of highway engineering are continuously being improved. Highway engineers must take into account future traffic flows, design of highway intersections/interchanges, geometric alignment and design, highway pavement materials and design, structural design of pavement thickness, and pavement maintenance.
Freezing rain is rain maintained at temperatures below freezing by the ambient air mass that causes freezing on contact with surfaces. Unlike a mixture of rain and snow or ice pellets, freezing rain is made entirely of liquid droplets. The raindrops become supercooled while passing through a sub-freezing layer of air hundreds of meters above the ground, and then freeze upon impact with any surface they encounter, including the ground, trees, electrical wires, aircraft, and automobiles. The resulting ice, called glaze ice, can accumulate to a thickness of several centimeters and cover all exposed surfaces. The METAR code for freezing rain is FZRA.
A road surface or pavement is the durable surface material laid down on an area intended to sustain vehicular or foot traffic, such as a road or walkway. In the past, gravel road surfaces, macadam, hoggin, cobblestone and granite setts were extensively used, but these have mostly been replaced by asphalt or concrete laid on a compacted base course. Asphalt mixtures have been used in pavement construction since the beginning of the 20th century and are of two types: metalled (hard-surfaced) and unmetalled roads. Metalled roadways are made to sustain vehicular load and so are usually made on frequently used roads. Unmetalled roads, also known as gravel roads or dirt roads, are rough and can sustain less weight. Road surfaces are frequently marked to guide traffic.
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.
Rolling resistance, sometimes called rolling friction or rolling drag, is the force resisting the motion when a body rolls on a surface. It is mainly caused by non-elastic effects; that is, not all the energy needed for deformation of the wheel, roadbed, etc., is recovered when the pressure is removed. Two forms of this are hysteresis losses, and permanent (plastic) deformation of the object or the surface. Note that the slippage between the wheel and the surface also results in energy dissipation. Although some researchers have included this term in rolling resistance, some suggest that this dissipation term should be treated separately from rolling resistance because it is due to the applied torque to the wheel and the resultant slip between the wheel and ground, which is called slip loss or slip resistance. In addition, only the so-called slip resistance involves friction, therefore the name "rolling friction" is to an extent a misnomer.
Ice racing is a form of racing that uses cars, motorcycles, snowmobiles, all-terrain vehicles, or other motorized vehicles. Ice racing takes place on frozen lakes or rivers, or on groomed frozen lots. As cold weather is a requirement for natural ice, it is usually found at higher latitudes in Canada, the northern United States, and in northern Europe, although limited indoor events are held in warmer climates, typically on ice hockey rinks. Tracks in North America vary from 1/4 mile to several mile-long circuits.
A winter road is a seasonal road only usable during the winter, i.e. it has to be re-built every year. This road typically runs over land and over frozen lakes, rivers, swamps, and sea ice. Segments of a winter road that cross an expanse of floating ice are also referred to as an ice road or an ice bridge.
A gravel road is a type of unpaved road surfaced with gravel that has been brought to the site from a quarry or stream bed. Gravel roads are common in less-developed nations, and also in the rural areas of developed nations such as Canada and the United States. In New Zealand, and other Commonwealth countries, they may be known as metal roads. They may be referred to as "dirt roads" in common speech, but that term is used more for unimproved roads with no surface material added. If well constructed and maintained, a gravel road is an all-weather road.
A paver is a piece of construction equipment used to lay asphalt concrete or Portland cement concrete on roads, bridges, parking lots and other such places. It lays the material flat and provides minor compaction. This is typically followed by final compaction by a road roller.
A winter service vehicle (WSV), or snow removal vehicle, is a vehicle specially designed or adapted to clear thoroughfares of ice and snow. Winter service vehicles are usually based on a dump truck chassis, with adaptations allowing them to carry specially designed snow removal equipment. Many authorities also use smaller vehicles on sidewalks, footpaths, and cycleways. Road maintenance agencies and contractors in temperate or polar areas often own several winter service vehicles, using them to keep the roads clear of snow and ice and safe for driving during winter. Airports use winter service vehicles to keep both aircraft surfaces, and runways and taxiways free of snow and ice, which, besides endangering aircraft takeoff and landing, can interfere with the aerodynamics of the craft.
The Resonance method of ice destruction means breaking sheet-ice which has formed over a body of water by causing the ice and water to oscillate up and down until the ice suffers sufficient mechanical fatigue to cause a fracture.
Snow socks are textile alternatives to snow chains. Snow sock devices wrap around the tires of a vehicle to increase traction on snow and ice. Snow socks are normally composed of a woven fabric with an elastomer attached to the inner and/or outer edge. The woven fabric covers the tire tread and is the contact point between the vehicle and the road. The elastomer keeps the snow sock in place and facilitates with installation. Some snow sock models have an additional component that covers the rim of the tire, which prevents snow or debris from gathering between the tread of the tire and the inner side of the woven fabric.
Offshore geotechnical engineering is a sub-field of geotechnical engineering. It is concerned with foundation design, construction, maintenance and decommissioning for human-made structures in the sea. Oil platforms, artificial islands and submarine pipelines are examples of such structures. The seabed has to be able to withstand the weight of these structures and the applied loads. Geohazards must also be taken into account. The need for offshore developments stems from a gradual depletion of hydrocarbon reserves onshore or near the coastlines, as new fields are being developed at greater distances offshore and in deeper water, with a corresponding adaptation of the offshore site investigations. Today, there are more than 7,000 offshore platforms operating at a water depth up to and exceeding 2000 m. A typical field development extends over tens of square kilometers, and may comprise several fixed structures, infield flowlines with an export pipeline either to the shoreline or connected to a regional trunkline.
A snow road is a type of winter road, which is a road that is used or trafficable only in the winter. Snow roads make up some or all of the on-land segments of a winter road. The snow is either compacted in place or, when there is not enough of it, is hauled from elsewhere, then compacted. The snow may be processed, for instance, by agitation to reduce the size of the particles before compaction. Additional snow is also used to help protect the vegetation and as a means of improving trafficability. This snow, sometimes referred to as 'snow pavement', can be compacted to various level, depending on requirements and available equipment – a higher compaction will accommodate heavier vehicles and higher tire pressures.