The high-resolution measurement allows continuous blower control and effective optimization of power consumption of the fans. The TMS3000 system has been successfully used in world's longest tunnels (e.g. the Gotthard in Switzerland or Plabutsch in Austria) and also shorter tunnels (e.g. University in Düsseldorf, Germany).

Measurement is based on high-precision pressure measurement using special differential Pitot tube sensors (DPS) which results in accurate flow measurement of the air through the tunnel.

This system has many advantages:

• Robust sensors made of stainless steel.
• No moving parts.
• No active electronic components in the road tunnel
• The measuring system is practically maintenance-free (recommended inspection interval – 5 years).
• Excellent measurement is still guaranteed even in case of fire (available for operating temperatures of up to 1200 °C).
• High resolution of less than 0.1 m/s in both flow directions.
• Information on flow rate through the tunnel cross-section gives precise flow measurement without any impact of road traffic.
• Optional calibration by our accredited test rig installation for air flow (ISO 17025).
• An absolute zero-point stability thanks to pneumatic Autozero system
  (automatically repeating "zeroing" of the deltaP measuring cells).
• Absolute air pressure measurement (barometric pressure) is already included.
• The Pitot tube sensors protrude only for approx. 40 cm into the driving area.
• Very easy dismounting of the deltaP Pitot tubes without tools during periodic cleaning of the tunnel walls.

The ventilation of road tunnels ensures that noxic gases (above all carbon monoxide) and dirt particles are removed from the tunnel. The ventilation will become efficient and economic if it can be controlled using the flow rate of the air. Flow measurement systems TMS 3000 measure the exact flow rate in the longitudinal direction of the tunnel. Local turbulences constantly caused by traffic in the tunnel have no influence.

TMS 3000 averages the flow rate vz in the longitudinal direction of the tunnel (z-direction) through the tunnel cross-section and thus measures the actual volumetric flow rate of the air through the tunnel.

Transversal components vx and vy that are not involved in air transportation in the longitudinal direction z of the tunnel don‘t contribute to the measuring signal.

Airflow measurement systems TMS 3000 are specifically designed for working under conditions prevailing in road tunnels. In the driving area there are only robust mechanical sensors made of stainless steel, the evaluation electronics is located in a separate control room.

The high-resolution measurement allows continuous blower control and thus an effective optimization of fans and power consumtion. Our devices have been successfully used in the longest tunnels (e.g. the St.Gotthard Tunnel in Switzerland or Plabutsch in Austria) or shorter tunnels (e.g. University Tunnel in Düsseldorf, Germany).

Measurement is based on high-precision differential pressure measurement which results in accurate flow measurement of the air through the tunnel. The data from the separately mounted field transmitters are transferred digitally into the evaluation unit (RS 485).

Even larger traffic density in a tunnnel cannot affect the measurement. The former can lead to significant measurement errors in ultrasonic measurements with time-of-flight method.