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COST 309
Road Weather Conditions

COST 309 image

Chairman : Mr Erkki Nysten (FIN)
Finnish Meteorological Institute

Vice-Chairman : Mr Ingmar Olofsson (S)

Scientific Secretary : European Commission
Fax: +32 2 296 37 65
Email: (email removed)


4 years; completed December 1990.


11 COST Countries: Austria, Denmark, Finland, France, The Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the United Kingdom.


To improve traffic safety and traffic flow and to reduce winter road maintenance costs and environmental problems, by the following means:

  • exploring the most effective methods of detecting, forecasting and mapping hazardous weather related road conditions and taking action to improve their efficacy;
  • quantifying the costs and benefits of such methods and actions;
  • recommending areas where common research can be carried out and common operational standards established.


The main research areas of COST 309 were defined as: road weather detection, forecasting, statistics and service strategies. The specific topics explored were:

  • Sensors and measuring systems : comparing sensors and developing new sensors for measuring road conditions (e.g. freezing point, de-icing concentration, etc.);
  • Overall systems, thermal mapping, data transmission : an optimum network of suitably sited sensors can use all available weather and road information to identify road sections that are high accident risks due to climatic conditions; this could help in the planning of warning device and weather station installation, and the de-icing of pavements;
  • Fog detection and prediction : developing new sensors for measuring visibility and new methods for forecasting fog;
  • Weather radar : investigating the usefulness of weather radar information for forecasting road weather conditions and for use by road managers;
  • Short term and immediate prediction of road conditions : evaluating prediction methods and develop models of road surface conditions;
  • Weather index : developing a standardised national weather atlas, which would be of use when comparing methods and resources for winter road maintenance;
  • Weather and accidents : establishing a standardised recording practice for road accidents, weather conditions and road conditions; this could be used to compile a database that could be useful for evaluating weather related road maintenance activities;
  • Cost-benefit analysis of road weather services : covering costs/benefits to local authorities and road users, accident and environmental costs;
  • Communication between meteorologists and road maintenance authorities : promoting better use by road maintenance personnel of information provided by the meteorological service and local weather stations;
  • Dissemination of information between meteorological stations/to road users : assessing types of information that could be of use to road users and technical means of dissemination; standardising road weather information and descriptions of road surface conditions;
  • Effects of de-icing agents : evaluating the best way of using meteorological data to optimise salting; determining the effect of de-icing agents under different weather conditions.

According to the final report of COST 309, despite relatively high installation costs, the implementation of road weather systems should reap benefits in terms of better safety, long-term cost savings, optimum response to critical weather situations and minimising environmental damage.

When calculating the benefits of road weather systems, the savings in driving costs should also be included, as well as the straight maintenance benefits.


The main aims of the road weather systems are to improve traffic safety, to reduce traffic and maintenance costs and to optimise road maintenance operation. In order to achieve these aims, road authorities must be provided with tailored local and regional weather systems which enable them to minimise the likelihood of weather related accidents by providing timely, effective information to drivers. A number of sophisticated tools are available to the road manager. Combining weather forecasting expertise with modern environmental monitoring and display systems can have a substantial effect on the impact of adverse weather conditions on road transport. Driver information can be provided via radio, television, telephone or variable message signs (VMS), and enables the driver to plan potential delays and route changes in addition to improving safety.

Benefits to Different Users

COST 309 is of value to road users, national and local road authorities, emergency services, meteorologists, road engineers and manufacturers of the instruments used.

Related Activities


Final Report
Manuscript completed in December 1990
1992 - 146 pp - 16.2 x 22.9 cm
ISBN 92-826-3244-X - EUR 13847 - Price: ECU 12.50
Also available in French

Image Last Updated: 05-02-1999
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