The research field “Winter traffic and winter road maintenance” at VTI includes:
1. Winter road maintenance
2. The vehicle and its winter equipment
3. Winter driver training and driver behaviour.
1. Winter road maintenance
• On-going research, VINTERMODELLEN, is a socio-economic model for calculation of optimal winter strategies and standard for national road maintenance.
The following sub-models in VINTERMODELLEN (partly for assessing effects) must be produced and linked to each other. They include:
- a road condition model, which describes how different road conditions occur and change under the influence of weather, winter road maintenance and traffic
- an accessibility model, which indicates how vehicle speeds and traffic flows vary with weather, road conditions and visibility
- an accident model, where the risks of accidents and injury consequences are described in the first place as a function of type and frequency for different road conditions and vehicle speeds
- a vehicle cost model, which comprises fuel consumption, wear and corrosion
- an environment model, which describes primarily the effects of salting on vegetation and groundwater
- a maintenance action model, which indicates the cost of winter maintenance actions as well as wear and damage to roads and bridges
- a model which places a value on each of the above mentioned effects
- a model for optimisation of strategies for winter road maintenance.
The prototype of VINTERMODELLEN will go through sensitivity analysis, calibration and verification during the next few years.
• Winter road maintenance in urban areas, focusing on safety and accessibility for pedestrians and cyclists.
• Further development of the Winter Road Measuring Vehicle which can measure the air temperature, road surface temperature, humidity, snow depth, transverse evenness, friction and freezing temperature for wet or moist road surfaces while travelling at normal traffic speeds.
The Winter Road Measuring Vehicle can be used for duties such as:
- measuring and reporting the achieved standard of the road network
- analysing the reasons why winter road maintenance does not produce the intended result
- developing and evaluating de-icing methods and strategies for different road types, traffic volumes, weather types, road conditions, etc.
- testing and evaluating different de-icing agents.
• Continued development of equipment for friction measurement. One of the latest types developed, the BV14, is fitted to the Winter Road Measuring Vehicle and measures friction behind both rear wheels at the same time. Another addition is the PFT, a hand pushed measuring trolley that is especially suitable for friction measurement on limited surfaces, e.g. road markings, pavements and cycleways.
• Measuring the transport of road salt and pollution from the road to the nearby environment. VTI has been studying this problem for a long period, e.g. by collecting specimens of soil, water and vegetation in test areas close to winter salted roads.
• Studies of salt damage on vegetation and cultural heritage (ancient monuments and sites) close to the road.
• Compiling the effects of salt usage on the environment, concrete structures, vehicles, etc.
• The spreading of wear particles in relation to winter tyre usage and their properties and potential environmental and health effects.
To obtain a comprehensive picture of the problem, studies of relations between measures and effects may need to be complemented with data on road user attitudes or habits. In many cases, this makes use of questionnaire studies under VTI management.
2. The vehicle and its winter equipment
In this area VTI’s efforts mainly involve the following:
• Expert work for regulations at national and international level:
- Studies at VTI forming the basis for Swedish legislation on the quality and use of studded tyres.
• Development of experimental test methods and those based on computer simulation:
- VTI has developed some of the world’s most advanced equipment for studies of the steering and braking characteristics of tyres on ice and the wear effect of studded tyres on road pavements, independent of weather conditions
- VTI has developed and acquired in-vehicle measurement equipment for making studies of tyre/road friction and evaluating criteria for stability, steerability and braking performance directly in the field when studying tyres, brakes and propulsion systems.
• Experimental tests of functional characteristics.
• Computer simulation of functional characteristics.
• Studies of effects on safety, accessibility, vehicle and environmental costs of vehicle equipment and calculation of the socio-economic consequences.
• A study of buses driving on winter roads started in the beginning of 2006 with the aim of better traffic safety and working environment.
• VTI is able to carry out surveys of information not found in different vehicle databases but required in studies of effects, e.g. the proportion of vehicles using studded tyres and the quality of tyres and studs.
3. Driver education and driver behaviour in wintertime
Skid training is a compulsory part of driver licensing. However, international experience indicates that the increase in the traffic safety effect may be lost if the training is not correctly designed.
VTI’s research comprises:
• Development of Swedish skid training so that it actually leads to improved safety. Among other things, this work has contributed to further emphasis during training on risk awareness and insight into the learner driver’s own limitations. VTI’s research work, partly in the form of a long-term research program conducted jointly with the Swedish Road Administration and the various educational organisations, has laid the foundation for a recently executed reconstruction and implementation of a new national course schedule for obligatory skid training.
• The knowledge of factors influencing road user behaviour in winter traffic is poor and little is known about which senses (visual, auditory and tactile) the driver uses when judging road condition. This can be studied both experimentally on the road and in the VTI driving simulator.