Harald Norem - Academia.edu (original) (raw)

Papers by Harald Norem

Geo-marine Letters, Apr 7, 1997

Debris lobes with characteristic lengths, widths, and thickness of 30-200 km, 2-10 km, and 10-50 ... more Debris lobes with characteristic lengths, widths, and thickness of 30-200 km, 2-10 km, and 10-50 m, respectively, represent the main building blocks of deep-sea fans along the Norwegian-Barents Sea continental margin. Their formation is closely related to the input of clay-rich sediments to the upper continental slope by glaciers during periods of maximum ice advance. It is likely that slide release was a consequence of an instability arising from high sedimentation rates on the upper continental slope. The flow behavior of the debris lobes can be described by a Bingham flow model.

International Snow Science Workshop 2016 Proceedings, Breckenridge, CO, USA, Oct 2, 2016

The aim of the present project was to evaluate four different models by using objective criteria ... more The aim of the present project was to evaluate four different models by using objective criteria and constant parameters, and to consider the models' applicability to Norwegian avalanches. RAMMS, Elba+, the Alpha-Beta model and the Energy Line model are the assessed models. The models are applied to 15 well-documented Norwegian avalanches with return periods from 100 to 300 years. RAMMS and Elba+ represent numerical dynamical models, whereas the Alpha-Beta model and the Energy Line model are empirical models based on topographic parameters. A main concern of the project was to compare the accuracy of the numerical and empirical models in terms of run-out distance, maximum velocity and velocity distribution in the run-out zone. The results showed that the two numerical models, RAMMS and Elba+, consistently modelled shorter run-out distances than recorded ones, but they had the best correlation coefficients in the statistical analysis. On the other hand, the two topographic models, developed for Norwegian conditions, had the least deviation in average run-out distance. All the models calculate maximum velocities within a realistic range. However, RAMMS and Elba+ probably calculate too small velocity gradients in the run-out zone compared to recordings from full-scale experiments. The Energy Line model, however, provided values that are more realistic. An accurately estimated distribution is extremely important when dimensioning avalanche protection measures. The statistical analysis shows that RAMMS and the Energy Line model overall provide the best results.

New Challenges for Winter Road Service. XIth International Winter Road CongressWorld Road Association - PIARC, 2002

On cold days with light snow partly covering the pavement, trucks and buses generate high wind sh... more On cold days with light snow partly covering the pavement, trucks and buses generate high wind shear stresses along the pavement and this results in the snow being set into motion. At high traffic speeds this type of suspended snow, "the snow smoke" dramatically reduces visibility for traffic behind the vehicle. In all Nordic countries several severe traffic accidents have been recorded because of the difficult driving conditions made by this "snow smoke". This paper describes the solutions required in order to reduce the problems associated with "snow smoke". These solutions are: (1) to improve the winter maintenance of roads in order to remove the thin layer of non-coherent snow particles on the roads; (2) to implement salting on all roads on days when the problem occurs; and (2) to redesign heavy cars to reduce or direct the generation of the snow smoke. The problems with the snow smoke may only be reduced to a limited extent by improving the winter maintenance, since some particles will always be available and implementing salting on all roads are costly. The actual idea behind this paper was to study the measures on the redesign of the trucks and buses to reduce the negative effects of snow smoke. This can either be done by: (1) reducing the amounts of particles that are brought into suspension by the generated wakes; or (2) directing the particles to the right hand side of the road. An additional effect of the redesign should preferably be to reduce the total air resistance of the trucks in order to save fuel and to improve the spreading of dirt from the pavement.

In areas with no trees and strong winds, drifting snow may be a major problem of daily life in re... more In areas with no trees and strong winds, drifting snow may be a major problem of daily life in residential areas. This paper describes an evaluation of two living areas in Hammerfest, Northern Norway, at a latitude of 70 deg 40' North. The paper deals with the evaluation of the areas, to critically analyze the background for the planning and to gain experience for new projects. The use of climatological data to find the critical wind directions and to estimate the magnitude of the snow drift problem is described. The experiences concerning the design and the location of garages and entrances to the houses due to the wind directions and to the topography are also described, as well as the need for an outer sheltering of the whole area. Recommendations for the location and the design of access roads and places for storing removed snow are given.

During strong winds, drifting snow causes problems on roads in many harsh winter climate countrie... more During strong winds, drifting snow causes problems on roads in many harsh winter climate countries. Increased snow-removal costs, reduced access and safety problems are typical results of excessive snowdrift sedimentation and bad visibility along many roads in the exposed regions.The objective of the study is to enhance knowledge on drifting snow behaviour on roads and to develop design criteria for better road construction in mountainous areas and other areas where frequent snowfall and strong winds occur. The study is focused on road cuts, because road sections with terrain cuts are the most vulnerable both concerning visibility and snow depositing on the road. The study is mainly based on CFD (Computational Fluid Dynamics) and field measurements. Field studies were carried out in both Norway and Iceland, and include snow surveys, wind measurements and a visibility registration. A wind tunnel study on snow drifting around a model avalanche dam is also a part of the thesis.Wind flow in road cuts was simulated and the resulting wind speed distribution and flow pattern were compared to snow surveys. On basis of this comparison and by considering experimental relationships between wind flow and snow drifting, new design principles were proposed.An important result of the study is the distinction between wind flow and snow drifting in gently sloping road cuts and in steep road cuts, respectively. Wind and snow drifting in gently sloping cuts and on leeward facing hillsides can usually be described as a two-dimensional flow. On the other hand, steep road cuts generally create a vortex moving parallel the road, and the resulting flow pattern must be described in three dimensions.Results for gently sloping road cuts suggest that in order to achieve a drift free road, it must be placed downwind of the equilibrium snowdrift surface. This implies that a considerable speed up in the wind has to occur over the road embankment to facilitate snow erosion from the road surface. A statistical method to predict equilibrium snowdrift surfaces by using terrain information only is proposed. The model is based on weighing terrain slopes, and creates a streamlined surface to imitate the shape of the equilibrium snowdrift surface.For steep cuts, a design that features an expanded cut width at both ends of the cut was tested. The design increases the speed of the transverse vortex under the cut edge, and generates less turbulence than a straight cut, which is believed to have a positive effect on the visibility. The proposed design also moves the critical low speed areas away from the road, and should therefore result in less snow accumulation on the road.It is concluded that plain wind flow simulations are a helpful tool to learn about snow drifting on roads, and can be used to test the quality of a proposed design. The suggested design principles for road cuts are promising for full scale testing.

Transportation Research E-Circular, Jun 1, 2008

Field observations have been made to study the development of salt amount on road surfaces after ... more Field observations have been made to study the development of salt amount on road surfaces after salt application. The objective of the study has been to understand the mechanisms that remove salt from road surfaces after spreading and identify important parameters behind the mechanisms. After salt application, salt is transported from the road surface by the three mechanisms: blowoff, spray-off, and runoff. The mechanisms are affected by several parameters grouped in weather parameters, traffic parameters, and road characteristics. Four case studies are presented where the amount of salt was measured with SOBO 20. Weather, traffic, and winter maintenance activities were recorded. The amount of water on the road surface was measured by using absorbent textiles. The results show that the amount of water on the road surface controls the development of salt amount on the road surface. Both the mechanisms of salt loss and how much salt becomes dissolved are governed by the amount of water on the road surface. On a wet road surface more salt will be dissolved compared to a moist road surface. This leads to a higher peak value in the amount of dissolved salt which is detected with the used instrument. Further, on a wet road surface there will be a more rapid loss of salt due to a higher effect of spray-off.

Annals of Glaciology, 1985

The Ryggfonn project is a full scale experiment carried out to investigate the impact of avalanch... more The Ryggfonn project is a full scale experiment carried out to investigate the impact of avalanches on structures and the effects of a retaining dam in the avalanche path. The vertical drop of the avalanche path is 910 m and the volume of the avalanches is 20-lOO 000 m 3. The experimental setup consists of: a 15 m high retaining dam in the runout zone, instrumented with strain gauges on a 6.5 m steel mast and a load cell on a 1.0 m mast, plus a 4.5 m high concrete structure instrumented with three 0.72 m 2 load cells, and three transmission line conductors strung across the avalanche path. The recorded analogue signals are digitized using Pulse-Code-Modulation (PCM) and recorded on a magnetic tape recorder. Up to May 1984, speed data from five avalanches have been analysed, and impact pressures have been recorded from three of them. The maximum speeds vary between 38 m/ s and 60 m/ so The maximum recorded impact pressure was 541 kPa, and averaged 220 kPa over a 15 second interval. A maximum pressure of 83 kPa was measured on a load cell buried under snow at the base of the concrete structure.

Transportation Research Record, 2011

This paper is part of a larger project to study how the quantity of salt on road surfaces develop... more This paper is part of a larger project to study how the quantity of salt on road surfaces develops after salt application. The goal of the work presented in this paper was to identify the physical processes that control the development of salt quantities on road surfaces. Field observations were made to study the quantity of salt after application. The results suggest that the development of salt quantity after salt application is controlled by three processes: initial loss, dissolution of salt, and loss of salt. A theoretical approach was taken to investigate the process of salt dissolution. The paper presents a principal, physically based model of the measured salt quantity on road surfaces as a function of traffic. It is proposed that the dissolution of salt be expressed by an exponential equation and that the rate of dissolution depends mainly on the quantity of water on the road. The loss of salt caused by blow-off and spray-off is considered to follow an exponential curve. The resultant equation that incorporated the dissolution and the loss was compared with field observations of moist and wet road surfaces.

Journal of Cold Regions Engineering, Dec 1, 2009

The aims of the presentation are to discuss the efficiency of the different methods for friction ... more The aims of the presentation are to discuss the efficiency of the different methods for friction control of winter roads on the safety and accessibility due to climatic conditions, to show that the climate should be an important factor in selecting the strategies for winter maintenance and to establish climatic parameters that may be helpful in making those decisions. The analyses are based on Swedish data assembled by VTI on road accidents involving fatalities and severe injuries, road surface conditions and climate. The accident and the road condition recordings are compared to self-defined climatic parameters, which describe the severity, stability and instability of the winter climate in the regions investigated. The parameters are assumed to describe whether salting or sanding is favorable/unfavorable for friction control. The results of the analyses show that the effect of salting is substantial for improving accessibility. Generally the number of winter accidents resulting in fatalities and severe ...

Annals of Glaciology, 1993

During two winters, 1990-92, the dynamic structures of snow avalanches were studied in western No... more During two winters, 1990-92, the dynamic structures of snow avalanches were studied in western Norway. Artificially released wet-snow avalanches ran down the avalanche chute and stopped in front of the retaining dam. Running velocity distributions were obtained not only by video tape recorder, but also by various other recording instruments. Internal velocity was derived for the last avalanche by frequency analysis of impact pressure and optical sensor data. The vertical velocity shear of the avalanche flow has been estimated to be in the range 1-lOS-I.

Marine geotechnology, 1990

The European project ROADEX, within the European Union Northern Periphery Programme, on the opera... more The European project ROADEX, within the European Union Northern Periphery Programme, on the operation of roads in winter climates was started in 1999 and will last for 3 years. The participating countries are Finland, Sweden, Norway, Iceland, and Scotland. The aim of the study was to exchange experience and carry out a state-of-the-art study on two separate issues: the management of winter roads caused by traffic loads, load restrictions, and how to improve road conditions; and design, maintenance, and operation of roads exposed to drifting snow conditions. The paper deals with the practice within the five countries on the procedures to operate roads exposed to severe climatic conditions, mainly drifting snow. The factors concentrated on are safety procedures for controlling the traffic and, in extreme cases, closing the road; agencies responsible for closing roads; collecting information about weather and driving conditions, and the use of these in the daily maintenance and operation of the roads; and information on weather and driving conditions submitted to the road users. For each of these factors, a comparison of the procedures for each country is presented, along with recommendations for a best practice procedure.

Abstract : This report describes the use of climatic data for the design of highways situated in ... more Abstract : This report describes the use of climatic data for the design of highways situated in areas with drifting snow. It also concentrates on the cross sectional design of such highways. Three methods for snow depth surveying are tested and described. The report concludes that a combination of tachymetric and botanical methods is generally recommended for the surveying of snowdepths when planning mountain highways. (Author)

Annals of Glaciology, 1985

The paper describes experience gained in Norway regarding the design criteria and use in practice... more The paper describes experience gained in Norway regarding the design criteria and use in practice of snow fences. The paper is based on theoretical studies on drifting snow, model experiments and experience accumulated through practical consulting work. Snow fence design is a compromise between the storage capacity and mmlmlzation of dimensioning forces. Design considerations include fence height H , total snow fence density, and the gap between ground and fence. A gap of 0.15H-0.2H and a total density of 45% are usually recommended. On ridge crests the gap can be reduced to O.lH and in areas where snow depths exceed 2.0 m, it can be increased to O.3H. In such cases the fence density should be varied such that the total density, including the gap, will remain near 4S%. The height of the snow fences should be kept within 3.S-4.5 m and the snow fences should be erected on the windward side of obstacles that create snowdrifts. The minimum distance from fence to road should not be less than ISH; in certain circumstances in coastal climate, this can be reduced to 10H.

The safety requirements are discussed for keeping high altitude roads open throughout the year in... more The safety requirements are discussed for keeping high altitude roads open throughout the year in countries with a cold climate. Different design criteria for locating such roads based on climatic conditions are examined in some detail. A survey of snow accumulation problems in the area in question is of major importance in this connection. Alignment of the road in relation to the countryside, snow drifts and directions of prevailing wind are also mentioned. The cross section profile of the road in cuts and fills is discussed, and it is emphasized that although embankments are preferred these should be relatively low since the use of guard rails will usually cause accumulation of snow. In cuts there is a general tendency for snow to accumulate and special care must be taken either to accomodate the snow beside the road in the cut or to prevent it from reaching the cut. Special solutions like elevated roads are mentioned. In conclusion the author stresses the importance of locating the road in areas of moderate winds but by-passing areas of heavy snow accumulation. /TRRL/

The article deals with the main criteria for the location of the road in relation to certain phys... more The article deals with the main criteria for the location of the road in relation to certain physical details and prevailing winds, and design rules for the cross section profiles of mountain roads are proposed. The latter has been established on the basis of model tests using sand in running water to simulate drifting snow. The features investigated were embankment gradients, crest curvature and the effects of guardrails. In the case of cuttings the effects of a wide ditch on the windward side of the road were examined. It is recommended that embankments be designed with an effective embankment height equal to the height of the local snow depths and a curvature at the crest of radius twice the embankment height. The slopes should have a gradient of 1:2 and guardrails should be avoided. Instead of guardrails gentler slopes should be employed where necessary. In areas with heavy snowdrifts, road cuttings should be designed so that a line drawn from the snow surface at the edge of the cutting to the verge of the road forms an angle with the slope of the ground of 1:6, 5 measured in the direction of the wind. In particularly hilly areas and in areas with small quantities of drifting snow, cuttings are recommended with a 3-metres wide ditch and the same gradient as lowland cuttings. To obtain the full effect of the ditch, snow should be removed from the ditch after each snowstorm. /TRRL/

Norway is heavily exposed to avalanches due to its topography and its geographical location. On a... more Norway is heavily exposed to avalanches due to its topography and its geographical location. On a yearly basis the elements of danger are nevertheless small. On an average one road-user is killed per year, and ten cars are damaged by avalanches. The article states the safety methods in use, and the practice for preventing accidents, for example by giving an evaluation of the risk of having an accident as a result of the avalanche, and the need for introducing a preventive closing of the road on stretches with danger of avalanches. (TRRL)

Geo-marine Letters, Apr 7, 1997

Debris lobes with characteristic lengths, widths, and thickness of 30-200 km, 2-10 km, and 10-50 ... more Debris lobes with characteristic lengths, widths, and thickness of 30-200 km, 2-10 km, and 10-50 m, respectively, represent the main building blocks of deep-sea fans along the Norwegian-Barents Sea continental margin. Their formation is closely related to the input of clay-rich sediments to the upper continental slope by glaciers during periods of maximum ice advance. It is likely that slide release was a consequence of an instability arising from high sedimentation rates on the upper continental slope. The flow behavior of the debris lobes can be described by a Bingham flow model.

International Snow Science Workshop 2016 Proceedings, Breckenridge, CO, USA, Oct 2, 2016

The aim of the present project was to evaluate four different models by using objective criteria ... more The aim of the present project was to evaluate four different models by using objective criteria and constant parameters, and to consider the models' applicability to Norwegian avalanches. RAMMS, Elba+, the Alpha-Beta model and the Energy Line model are the assessed models. The models are applied to 15 well-documented Norwegian avalanches with return periods from 100 to 300 years. RAMMS and Elba+ represent numerical dynamical models, whereas the Alpha-Beta model and the Energy Line model are empirical models based on topographic parameters. A main concern of the project was to compare the accuracy of the numerical and empirical models in terms of run-out distance, maximum velocity and velocity distribution in the run-out zone. The results showed that the two numerical models, RAMMS and Elba+, consistently modelled shorter run-out distances than recorded ones, but they had the best correlation coefficients in the statistical analysis. On the other hand, the two topographic models, developed for Norwegian conditions, had the least deviation in average run-out distance. All the models calculate maximum velocities within a realistic range. However, RAMMS and Elba+ probably calculate too small velocity gradients in the run-out zone compared to recordings from full-scale experiments. The Energy Line model, however, provided values that are more realistic. An accurately estimated distribution is extremely important when dimensioning avalanche protection measures. The statistical analysis shows that RAMMS and the Energy Line model overall provide the best results.

New Challenges for Winter Road Service. XIth International Winter Road CongressWorld Road Association - PIARC, 2002

On cold days with light snow partly covering the pavement, trucks and buses generate high wind sh... more On cold days with light snow partly covering the pavement, trucks and buses generate high wind shear stresses along the pavement and this results in the snow being set into motion. At high traffic speeds this type of suspended snow, "the snow smoke" dramatically reduces visibility for traffic behind the vehicle. In all Nordic countries several severe traffic accidents have been recorded because of the difficult driving conditions made by this "snow smoke". This paper describes the solutions required in order to reduce the problems associated with "snow smoke". These solutions are: (1) to improve the winter maintenance of roads in order to remove the thin layer of non-coherent snow particles on the roads; (2) to implement salting on all roads on days when the problem occurs; and (2) to redesign heavy cars to reduce or direct the generation of the snow smoke. The problems with the snow smoke may only be reduced to a limited extent by improving the winter maintenance, since some particles will always be available and implementing salting on all roads are costly. The actual idea behind this paper was to study the measures on the redesign of the trucks and buses to reduce the negative effects of snow smoke. This can either be done by: (1) reducing the amounts of particles that are brought into suspension by the generated wakes; or (2) directing the particles to the right hand side of the road. An additional effect of the redesign should preferably be to reduce the total air resistance of the trucks in order to save fuel and to improve the spreading of dirt from the pavement.

In areas with no trees and strong winds, drifting snow may be a major problem of daily life in re... more In areas with no trees and strong winds, drifting snow may be a major problem of daily life in residential areas. This paper describes an evaluation of two living areas in Hammerfest, Northern Norway, at a latitude of 70 deg 40' North. The paper deals with the evaluation of the areas, to critically analyze the background for the planning and to gain experience for new projects. The use of climatological data to find the critical wind directions and to estimate the magnitude of the snow drift problem is described. The experiences concerning the design and the location of garages and entrances to the houses due to the wind directions and to the topography are also described, as well as the need for an outer sheltering of the whole area. Recommendations for the location and the design of access roads and places for storing removed snow are given.

During strong winds, drifting snow causes problems on roads in many harsh winter climate countrie... more During strong winds, drifting snow causes problems on roads in many harsh winter climate countries. Increased snow-removal costs, reduced access and safety problems are typical results of excessive snowdrift sedimentation and bad visibility along many roads in the exposed regions.The objective of the study is to enhance knowledge on drifting snow behaviour on roads and to develop design criteria for better road construction in mountainous areas and other areas where frequent snowfall and strong winds occur. The study is focused on road cuts, because road sections with terrain cuts are the most vulnerable both concerning visibility and snow depositing on the road. The study is mainly based on CFD (Computational Fluid Dynamics) and field measurements. Field studies were carried out in both Norway and Iceland, and include snow surveys, wind measurements and a visibility registration. A wind tunnel study on snow drifting around a model avalanche dam is also a part of the thesis.Wind flow in road cuts was simulated and the resulting wind speed distribution and flow pattern were compared to snow surveys. On basis of this comparison and by considering experimental relationships between wind flow and snow drifting, new design principles were proposed.An important result of the study is the distinction between wind flow and snow drifting in gently sloping road cuts and in steep road cuts, respectively. Wind and snow drifting in gently sloping cuts and on leeward facing hillsides can usually be described as a two-dimensional flow. On the other hand, steep road cuts generally create a vortex moving parallel the road, and the resulting flow pattern must be described in three dimensions.Results for gently sloping road cuts suggest that in order to achieve a drift free road, it must be placed downwind of the equilibrium snowdrift surface. This implies that a considerable speed up in the wind has to occur over the road embankment to facilitate snow erosion from the road surface. A statistical method to predict equilibrium snowdrift surfaces by using terrain information only is proposed. The model is based on weighing terrain slopes, and creates a streamlined surface to imitate the shape of the equilibrium snowdrift surface.For steep cuts, a design that features an expanded cut width at both ends of the cut was tested. The design increases the speed of the transverse vortex under the cut edge, and generates less turbulence than a straight cut, which is believed to have a positive effect on the visibility. The proposed design also moves the critical low speed areas away from the road, and should therefore result in less snow accumulation on the road.It is concluded that plain wind flow simulations are a helpful tool to learn about snow drifting on roads, and can be used to test the quality of a proposed design. The suggested design principles for road cuts are promising for full scale testing.

Transportation Research E-Circular, Jun 1, 2008

Field observations have been made to study the development of salt amount on road surfaces after ... more Field observations have been made to study the development of salt amount on road surfaces after salt application. The objective of the study has been to understand the mechanisms that remove salt from road surfaces after spreading and identify important parameters behind the mechanisms. After salt application, salt is transported from the road surface by the three mechanisms: blowoff, spray-off, and runoff. The mechanisms are affected by several parameters grouped in weather parameters, traffic parameters, and road characteristics. Four case studies are presented where the amount of salt was measured with SOBO 20. Weather, traffic, and winter maintenance activities were recorded. The amount of water on the road surface was measured by using absorbent textiles. The results show that the amount of water on the road surface controls the development of salt amount on the road surface. Both the mechanisms of salt loss and how much salt becomes dissolved are governed by the amount of water on the road surface. On a wet road surface more salt will be dissolved compared to a moist road surface. This leads to a higher peak value in the amount of dissolved salt which is detected with the used instrument. Further, on a wet road surface there will be a more rapid loss of salt due to a higher effect of spray-off.

Annals of Glaciology, 1985

The Ryggfonn project is a full scale experiment carried out to investigate the impact of avalanch... more The Ryggfonn project is a full scale experiment carried out to investigate the impact of avalanches on structures and the effects of a retaining dam in the avalanche path. The vertical drop of the avalanche path is 910 m and the volume of the avalanches is 20-lOO 000 m 3. The experimental setup consists of: a 15 m high retaining dam in the runout zone, instrumented with strain gauges on a 6.5 m steel mast and a load cell on a 1.0 m mast, plus a 4.5 m high concrete structure instrumented with three 0.72 m 2 load cells, and three transmission line conductors strung across the avalanche path. The recorded analogue signals are digitized using Pulse-Code-Modulation (PCM) and recorded on a magnetic tape recorder. Up to May 1984, speed data from five avalanches have been analysed, and impact pressures have been recorded from three of them. The maximum speeds vary between 38 m/ s and 60 m/ so The maximum recorded impact pressure was 541 kPa, and averaged 220 kPa over a 15 second interval. A maximum pressure of 83 kPa was measured on a load cell buried under snow at the base of the concrete structure.

Transportation Research Record, 2011

This paper is part of a larger project to study how the quantity of salt on road surfaces develop... more This paper is part of a larger project to study how the quantity of salt on road surfaces develops after salt application. The goal of the work presented in this paper was to identify the physical processes that control the development of salt quantities on road surfaces. Field observations were made to study the quantity of salt after application. The results suggest that the development of salt quantity after salt application is controlled by three processes: initial loss, dissolution of salt, and loss of salt. A theoretical approach was taken to investigate the process of salt dissolution. The paper presents a principal, physically based model of the measured salt quantity on road surfaces as a function of traffic. It is proposed that the dissolution of salt be expressed by an exponential equation and that the rate of dissolution depends mainly on the quantity of water on the road. The loss of salt caused by blow-off and spray-off is considered to follow an exponential curve. The resultant equation that incorporated the dissolution and the loss was compared with field observations of moist and wet road surfaces.

Journal of Cold Regions Engineering, Dec 1, 2009

The aims of the presentation are to discuss the efficiency of the different methods for friction ... more The aims of the presentation are to discuss the efficiency of the different methods for friction control of winter roads on the safety and accessibility due to climatic conditions, to show that the climate should be an important factor in selecting the strategies for winter maintenance and to establish climatic parameters that may be helpful in making those decisions. The analyses are based on Swedish data assembled by VTI on road accidents involving fatalities and severe injuries, road surface conditions and climate. The accident and the road condition recordings are compared to self-defined climatic parameters, which describe the severity, stability and instability of the winter climate in the regions investigated. The parameters are assumed to describe whether salting or sanding is favorable/unfavorable for friction control. The results of the analyses show that the effect of salting is substantial for improving accessibility. Generally the number of winter accidents resulting in fatalities and severe ...

Annals of Glaciology, 1993

During two winters, 1990-92, the dynamic structures of snow avalanches were studied in western No... more During two winters, 1990-92, the dynamic structures of snow avalanches were studied in western Norway. Artificially released wet-snow avalanches ran down the avalanche chute and stopped in front of the retaining dam. Running velocity distributions were obtained not only by video tape recorder, but also by various other recording instruments. Internal velocity was derived for the last avalanche by frequency analysis of impact pressure and optical sensor data. The vertical velocity shear of the avalanche flow has been estimated to be in the range 1-lOS-I.

Marine geotechnology, 1990

The European project ROADEX, within the European Union Northern Periphery Programme, on the opera... more The European project ROADEX, within the European Union Northern Periphery Programme, on the operation of roads in winter climates was started in 1999 and will last for 3 years. The participating countries are Finland, Sweden, Norway, Iceland, and Scotland. The aim of the study was to exchange experience and carry out a state-of-the-art study on two separate issues: the management of winter roads caused by traffic loads, load restrictions, and how to improve road conditions; and design, maintenance, and operation of roads exposed to drifting snow conditions. The paper deals with the practice within the five countries on the procedures to operate roads exposed to severe climatic conditions, mainly drifting snow. The factors concentrated on are safety procedures for controlling the traffic and, in extreme cases, closing the road; agencies responsible for closing roads; collecting information about weather and driving conditions, and the use of these in the daily maintenance and operation of the roads; and information on weather and driving conditions submitted to the road users. For each of these factors, a comparison of the procedures for each country is presented, along with recommendations for a best practice procedure.

Abstract : This report describes the use of climatic data for the design of highways situated in ... more Abstract : This report describes the use of climatic data for the design of highways situated in areas with drifting snow. It also concentrates on the cross sectional design of such highways. Three methods for snow depth surveying are tested and described. The report concludes that a combination of tachymetric and botanical methods is generally recommended for the surveying of snowdepths when planning mountain highways. (Author)

Annals of Glaciology, 1985

The paper describes experience gained in Norway regarding the design criteria and use in practice... more The paper describes experience gained in Norway regarding the design criteria and use in practice of snow fences. The paper is based on theoretical studies on drifting snow, model experiments and experience accumulated through practical consulting work. Snow fence design is a compromise between the storage capacity and mmlmlzation of dimensioning forces. Design considerations include fence height H , total snow fence density, and the gap between ground and fence. A gap of 0.15H-0.2H and a total density of 45% are usually recommended. On ridge crests the gap can be reduced to O.lH and in areas where snow depths exceed 2.0 m, it can be increased to O.3H. In such cases the fence density should be varied such that the total density, including the gap, will remain near 4S%. The height of the snow fences should be kept within 3.S-4.5 m and the snow fences should be erected on the windward side of obstacles that create snowdrifts. The minimum distance from fence to road should not be less than ISH; in certain circumstances in coastal climate, this can be reduced to 10H.

The safety requirements are discussed for keeping high altitude roads open throughout the year in... more The safety requirements are discussed for keeping high altitude roads open throughout the year in countries with a cold climate. Different design criteria for locating such roads based on climatic conditions are examined in some detail. A survey of snow accumulation problems in the area in question is of major importance in this connection. Alignment of the road in relation to the countryside, snow drifts and directions of prevailing wind are also mentioned. The cross section profile of the road in cuts and fills is discussed, and it is emphasized that although embankments are preferred these should be relatively low since the use of guard rails will usually cause accumulation of snow. In cuts there is a general tendency for snow to accumulate and special care must be taken either to accomodate the snow beside the road in the cut or to prevent it from reaching the cut. Special solutions like elevated roads are mentioned. In conclusion the author stresses the importance of locating the road in areas of moderate winds but by-passing areas of heavy snow accumulation. /TRRL/

The article deals with the main criteria for the location of the road in relation to certain phys... more The article deals with the main criteria for the location of the road in relation to certain physical details and prevailing winds, and design rules for the cross section profiles of mountain roads are proposed. The latter has been established on the basis of model tests using sand in running water to simulate drifting snow. The features investigated were embankment gradients, crest curvature and the effects of guardrails. In the case of cuttings the effects of a wide ditch on the windward side of the road were examined. It is recommended that embankments be designed with an effective embankment height equal to the height of the local snow depths and a curvature at the crest of radius twice the embankment height. The slopes should have a gradient of 1:2 and guardrails should be avoided. Instead of guardrails gentler slopes should be employed where necessary. In areas with heavy snowdrifts, road cuttings should be designed so that a line drawn from the snow surface at the edge of the cutting to the verge of the road forms an angle with the slope of the ground of 1:6, 5 measured in the direction of the wind. In particularly hilly areas and in areas with small quantities of drifting snow, cuttings are recommended with a 3-metres wide ditch and the same gradient as lowland cuttings. To obtain the full effect of the ditch, snow should be removed from the ditch after each snowstorm. /TRRL/

Norway is heavily exposed to avalanches due to its topography and its geographical location. On a... more Norway is heavily exposed to avalanches due to its topography and its geographical location. On a yearly basis the elements of danger are nevertheless small. On an average one road-user is killed per year, and ten cars are damaged by avalanches. The article states the safety methods in use, and the practice for preventing accidents, for example by giving an evaluation of the risk of having an accident as a result of the avalanche, and the need for introducing a preventive closing of the road on stretches with danger of avalanches. (TRRL)