Meteorological measured data in traffic engineeringRoad weather information systems for monitoring weather conditions in road traffic

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Road Weather Information Systems (RWIS)

Road Weather Information Systems (RWIS) comprise a variety of technologies and measuring instruments that have been specially developed for monitoring weather conditions in road traffic. These systems are of great importance for road operators and road maintenance organisations to take timely action to ensure safe road conditions depending on weather conditions.

The road weather information systems provide real-time data on the weather situation along the road infrastructure. The measured variables recorded include

Precipitation: detection of rain, snow and other types of precipitation.
Temperature: Measurement of air temperature.
Humidity: Monitoring of air humidity.
Wind speed: Measurement of wind speed and wind direction
Compact weather stations with combined sensors
Individual measuring masts and measuring stations‎

This data is continuously collected, combined and analysed to provide accurate information about current road conditions. This enables road operators to plan and implement preventive measures, such as the timely application of salt or other de-icing agents in the event of snowfall.

The environmental data determined as part of traffic control systems on motorways and motorways represent input variables for situation-dependent switching suggestions. Dynamic warnings and speed limits are used to warn road users of potentially dangerous environmental conditions (e.g. precipitation events, limited visibility, but also traffic volumes, etc.).

Significance for road operators: Thanks to the precise recording of weather parameters, road maintenance companies can react to dangerous conditions such as black ice formation or heavy snowfall at an early stage. This helps to reduce accidents and increase road safety. In addition, the integration of road weather information systems enables the efficient use of resources and helps to optimise maintenance service journeys. These measures minimise potential risks for road users and contribute to the long-term maintenance of the road infrastructure.‎

Norms and standards

CEN/TS 15518-4 is part of the European Committee for Standardisation (CEN) series of standards dealing with requirements and test methods for winter road maintenance. This specific standard specifies the technical requirements for equipment and systems for monitoring and forecasting road conditions in winter conditions (stationary equipment, road condition and weather information systems, RWIS).‎

Important requirements

Measurement accuracy: The devices must provide accurate and reliable data on the amount and type of precipitation, temperature, humidity, wind speed and other relevant weather parameters.
Reliability: The devices must function reliably even under extreme weather conditions and over long periods of time.
Ease of maintenance: The standard specifies requirements for the maintenance and calibration of the devices to ensure their accurate and operational
Interoperability: The devices must be able to be integrated into existing winter maintenance infrastructures and communicate with other systems and sensors.

Test methods

‎The standard describes specific test methods that are used to check the conformity of the devices with the specified requirements. These procedures ensure that the devices are tested and validated under controlled conditions.

Recommendation for winter maintenance

Devices that fulfil the requirements of CEN/TS 15518-4 are recommended for use in winter service. This recommendation is based on the high accuracy and reliability of the equipment, which is crucial for the effective performance of winter maintenance operations.
One recommendation is the Laser Precipitation Monitor:

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