Vaisala Thermal Mapping - Operational facts

• Vaisala Thermal Mapping surveys are undertaken by a fleet of specifically equipped vehicles, each mounted with a high resolution infrared thermometer connected to an automatic GPS data logger.

• Thermal Mapping surveys are normally carried out between the hours of 23:00 and sunrise during the months of November through to April (in the northern hemisphere).

• Vaisala Thermal Mapping surveys are carried out under normal road speeds, enabling surveys to be undertaken across different network types and environments including urban, rural, motorway, and airports.

• Thermal Mapping measurements are normally made at an interval of every five metres.  It is possible to change the resolution of data collection depending on network requirements.

• During Thermal Mapping surveys detailed observations are undertaken of prevailing meteorological conditions and road surface state.

• On sections of Dual Carriageways surveys are normally carried out on the inside lane.  However, if there are three lanes or more then surveys are normally undertaken in the centre lane.

• Before Thermal Mapping surveys are carried out a road/runway network is planned into smaller more manageable sections, by dividing it into c.30-50km Routes.  Routes will allow weather conditions to be continuously assessed throughout the survey.  The area one vehicle can cover during a survey night is referred to as a Sector. Therefore each Sector is comprised of a number of Routes.

• Sectors and Routes always follow a set order and are planned to incorporate a series of overlapping sections.  Overlaps allow all the data to be compared and eventually related together (i.e. as one survey).

• Thermal Maps are produced using collected data to provide a representation of the relative spatial variation of minimum road surface temperature under different weather conditions, indicating the relative differences as colour coded temperature categories.

Below - Extreme Thermal Map, Wigan Council, UK

• Thermal Maps can be produced in hard copy or electronic image formats. Thermal Maps are created in a GIS environment, geo-referenced and can be exported for inclusion in GIS platforms if required.

• Under an on-going programme of research and development, Vaisala continues to advance the Thermal Mapping process.  A key part of this is the regular testing and examination of the accuracy and repeatability of Thermal Mapping, the results of which are endorsed in international scientific journals. 

• Vaisala has established statistical procedures to validate the quality of data, and quantify the similarity between temperature patterns collected during different Thermal Mapping surveys.  Such processes demonstrate Vaisala’s Thermal Mapping process is reliable and the temperature variation along a road can always be reproduced under similar weather conditions.