Operating Manual V8.2/03.2017
Non Invasive Road Sensor
8
G. Lufft Mess- und Regeltechnik GmbH, Fellbach, Germany
4
Equipment Description
Depending on the requirements of the road traffic meteorological monitoring network,
sensors are installed in the roadways and / or "overhead". The Lufft NIRS31-UMB completes
the product range to include a non-invasive, intelligent sensor. The NIRS31-UMB provides
an alternative to the Lufft IRS31-UMB, especially for measuring points such as bridges,
which do not always allow direct installation of sensors in the roadway. In addition, at points
where asphalt repairs often take place, it is no longer necessary to remove the sensor
technology during repair works. The optical measuring device NIRS31-UMB for the detection
of water, ice and snow can be mounted on a bridge or mast. The measurement distance
between the measuring device and the road surface can be from 6 to 15 meters.
The sensor delivers established and commonly used decision-making data to winter
maintenance services, including water film height, road condition, road surface temperature
and freezing temperature. In addition, the sensor provides ice percentage and snow depth
readings. As the ice percentage on the road surface increases, the friction coefficient falls off
and this can be used as a guide in preventive road gritting decision-making.
In contrast to built-in road sensors, non-invasive sensors are not able to measure
underground soil temperature.
The equipment is connected by way of an 8 pole plug-in terminal and associated connection
cable (available in lengths of 15m and 50m).
The measured values can be requested over the RS485 interface in accordance with the
UMB protocol.
During commissioning, configuration and measurement polling takes place using the UMB
Config Tool (Windows
®
PC software).
4.1
Road Surface Temperature
Road surface temperature is measured by means of a non-invasive pyrometer, which is fully
integrated into the sensor.
4.2
Water Film Height
Measurement of the water film height on the road surface takes place by means of non-
invasive optical spectroscopy. The water film height is the proportion of liquid water.
4.3
Ice Layer Thickness
Measurement of the ice layer thickness on the road surface takes place by means of non-
invasive optical spectroscopy.
The ice layer thickness indicates the proportion of the frozen water as water
equivalent. The sum of water film height and ice layer thickness results the total water
equivalent.
4.4
Road Condition
The current road condition is determined from the measurement of water film height and
road surface temperature. The sensor calculates the following conditions: dry, damp, wet,
snow / ice and critical wetness.
4.5
Ice Percentage
The proportions of frozen solution are determined from the measurement data provided by
optical spectroscopy and transmitted as the ice percentage.
4.6
Freezing Temperature
The freezing temperature is determined on the basis of the current road surface temperature
and the measured ice percentages.
Note:
The freezing temperature can only be determined if ice percentages have already
formed. Determination of freezing temperature is currently limited to the de-icing agent
sodium chloride (NaCl).
