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23-533: The Sami Bridge was opened in 1993. Before this, there was a ferry during summer and ice road in winter. [REDACTED] Media related to Sami Bridge at Wikimedia Commons This article about a bridge in Norway is a stub . You can help Misplaced Pages by expanding it . This article about transport in Finland is a stub . You can help Misplaced Pages by expanding it . Ice road An ice road or ice bridge

46-491: A blizzard. 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. Also, because these structures are vulnerable to a warming climate, which reduces their operational lifespan, they may benefit from reinforcement along problematic segments, such as creek crossings and where

69-435: A floating ice sheet has been investigated via field testing. The most compelling evidence of such wave patterns, however, was captured by satellite imagery. 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. Either way, factors that need to be addressed before construction include

92-421: 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. For long-term loads,

115-437: A professional engineer may have to be consulted. As a vehicle travels on the road, a dynamic loading regime is exerted onto the ice cover. 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. At (and above) the critical speed, a series of waves will form behind and in front of

138-433: 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. This formula, which was initially proposed in 1971, 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

161-419: 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. Some sources prescribe a maximum of two hours for a stationary load, which is also what Gold recommended. Others advise to use the freeboard of the ice as an indicator, which can be done by drilling

184-607: A winter road is built mostly on floating ice, the occasional land crossings are called " portages " - the Tibbitt to Contwoyto Winter Road is an example. Winter roads facilitate transportation during the winter to, from and within isolated areas in the North where there are no permanent (also called 'all-weather' or 'all-season') roads. They enable supplies ( e.g. food, fuel, construction material) to be brought into communities in these areas. The only other alternative, providing there

207-500: Is a human-made structure that runs on a frozen water surface (a river, a lake or a sea water expanse). Ice roads are typically part of a winter road , but they can also be simple stand-alone structures, connecting two shorelines. 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. An ice road may be constructed year after year, for instance to service community needs during

230-499: 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). 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

253-417: Is most often native soil or muskeg frozen to a given depth, and locally, bedrock . These surfaces may either be bare or are overlain, as is most commonly the case, with a snow cover . Over-ice segments of winter roads are often referred to as ice crossings, ice bridges or, simply, ice roads. The weight of the vehicle is supported by the buoyancy of the floating ice and by its resistance to flexure . Where

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276-405: 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,

299-485: The close supervision of a professional engineer. 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: Thus, an ice cover may be able to safely support

322-484: The following: Factors that need to be considered in route selection include the following: Before first access to the ice, the following factors need to be considered: Snow cover removal is the first major operation in an ice road construction scheme. 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

345-410: 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 . 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

368-493: The ice cover: where σ max 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/cm (~ 50–150 lbs/in ), lower bound values are generally those that are used for safety purposes. This level of conservatism

391-476: 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. 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

414-401: The ice – one way to mitigate this issue is to avoid approaching shorelines at 90 degrees. 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). Dynamic loading of the ice cover may also dictate a minimum distance between vehicles. The effects of dynamic loading on

437-564: 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: 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. Surface deterioration can happen when the ice surface becomes too soft, or because of an excessive amount of meltwater on its surface. Mid-season road closures can also happen for similar reasons, and also because of inclement weather, such as

460-456: The road surface. However, tire chains may be stored in the vehicle for emergency purposes; they can also come in handy when traveling on a winter road with grades steeper than 8% on over-land segments. 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). These restrictions are to decrease

483-410: 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). 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

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506-426: The winter road crosses a shoreline. Winter road 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 . The foundations underlying over-land segments

529-514: The winter. It could also be for a single year or two, so as to supply particular operations, such as a hydroelectric project or offshore drill sites. 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. In order to meet

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