Tunnel Sensor Solutions for Safer Roads and Tunnels

As traffic density on our roads increases, the use of tunnels as a method for managing traffic flows has become more popular. Using tunnels for transportation has a number of benefits. It allows for a more efficient use of all available land (including underground), it can redirect traffic congestion from major city roads, it potentially decreases travel time and commutes, and it can reduce air pollution in residential areas. As more governments look to implement tunnel systems into their roadways, it is more important than ever to find ways to increase the availability of tunnels while at the same time improving safety for road and tunnel users.

For over 60 years, SICK has been helping road and tunnel operators take on this challenge, offering innovative products for not only measuring visibility and air quality in routine operation, but also for airflow measurement and smoke detection in emergencies. Here’s a quick recap on a few of our solutions for safe driving in tunnels.

Over-height Vehicle Detection

Vehicles of all different shapes and sizes use major roadways. If a vehicle is too tall to fit into a tunnel or underneath a bridge, it’s important to have a way to notify the person driving that vehicle before they potentially cause major infrastructure damage. This is where the HISIC450 from SICK can help.

When a vehicle is determined to be too tall for a tunnel entrance, low underpass, or low bridge, the HISIC450’s reliable stop and alarm signals activate once a vehicle infringes both photoelectric switches of the HISIC450. This signal is then combined with traffic data (e. g., induction loop signal). Even overheight vehicles traveling at speeds of up to 100 km/h are reliably detected. Due to its large beam diameter and high signal reserve, the detector can even cope with difficult weather conditions, (i.e., rain, snow, and dust clouds).

Fog monitoring

To avoid accidents in foggy conditions, a maximum speed limit can be set based on the measured visual range in the current conditions. This speed limit would be displayed on variable-messaging signs. The VISIC620 is a visual range measurement device that determines the standard visual range on roads or measures the visibility (as k-value or in mg/m³) in tunnels.

An automated self-test measures and compensates for possible front screen contamination. Furthermore, it offers excellent recognition of objects such as leaves or plants in the optical path. Therefore, the VISIC620 can measure fog reliably.

Vehicle overheating check

Now you can prevent vehicle fires caused by overheated vehicle parts before they even begin. The Vehicle Hot Spot Detector (VHD) profile system detects overheated vehicles. This enables them to be stopped before they enter the tunnel and potentially cause an accident or traffic jam.

The VHD profiling system combines thermal imaging cameras and 2D LiDAR sensors to detect overheated vehicles. This makes it possible to stop vehicles before they enter critical road sections such as tunnels or ferry/train boarding areas. The VHD system measures the temperature and dimension of each vehicle, determines the vehicle class, and generates a 3D model. This allows individual vehicle parts, such as the wheels, exhaust pipe or cargo hold, to be automatically identified based on individual thresholds. The system operates under free-flow traffic conditions at highway speeds around the clock (24/7).

Early fire detection

In the event of a fire inside a tunnel, every second counts. As a fire often manifests in the form of smoke much earlier than heat, smoke detectors are able to detect fires in the very early stages of development.

The VISIC50SF from SICK is a smoke detector that offers high-speed measurement to ensure fast and reliable smoke detection when tunnel fires occur. The VISIC50SF is very easy to mount, operate, and maintain. There is no need for alignment or parameter setting – measuring starts right away. With its IP6K9K enclosure rating, not only is the VISIC50SF able to withstand the harsh ambient conditions inside the tunnel, but also tunnel washing operations without any problems.

During the design phase, particular importance was placed on ensuring reliable operation and long maintenance intervals. That is why there are no moving parts. There is an optional version available with heating for fog evaporation. This allows the VISIC50SF to effortlessly meet your desired requirements, making it the perfect solution for the fast and reliable detection of fires.

Air Quality Measurement

The air quality inside a tunnel is also necessary information.  The continuous and precise measurement of minute NO2 concentrations provides the basis for ventilation control inside the tunnel. The VICOTEC320 from SICK measures very small concentrations of NO2 and NO as well as the visibility and temperature in road tunnels simultaneously and quickly. This is all done using industry-proven components, without test gases for zero and reference point. An automated, cyclic adjustment of zero and reference point ensures exact values. The rugged housing even withstands thorough tunnel washing operations without any problems.

In addition, the measurement of CO , NO provide greater visibility for ventilation control. The VICOTEC410 product family of compact analyzers detect measurands for visibility of carbon monoxide concentrations in road tunnels. This includes VICOTEC411 for determination of visibility, VICOTEC412 for measurement of CO concentration, and VICOTEC414 for the simultaneous measurement of visibility and CO concentration.

Airflow Measurement

Many tunnels also require the monitoring of air speed and direction for ventilation. The speed and direction of the airflow inside the tunnel must be measured to control ventilation. In the event of an emergency, this is the most important measurement to enable the fans to be controlled.

The FLOWSIC200 from SICK is used for the contact-free and accurate measurement of flow velocity and flow direction inside tunnels or exhaust ventilation ducts. Ultrasonic technology provides the cross-sectional mean average value of the flow velocity. This device is used for measurement necessary for optimal ventilation control and reducing running costs to a minimum when airflow is dictated by climatic conditions or by traffic.

In case of fires in tunnels the accurate, reliable and representative measurement of air velocity and direction across the tunnel is mandatory. This is the only way to check reliably the smoke propagation and to achieve the necessary information for optimal control of the ventilation system.

SICK – A Successful History of Providing Safe Solutions for Tunnel and Traffic Management

Most projects involving building and upgrading tunnel systems are long-term undertakings. Therefore, it is both important and critical to know that you have a strong and reliable partner at your side. With over 60 years of experience in tunnel sensor technology and evidence of more than 1,000 successfully implemented tunnel projects worldwide, SICK has precisely this solid foundation to offer.

Year-on-year sales growth, a continuous upward trend in investment in research and development, and increasing employee numbers make SICK a stable partner for the long term. A commitment to the continuous development of its product portfolio and global presence guarantee continuity and investment security.

Interested in learning more about SICK’s tunnel sensor solutions? Contact a SICK representative today at info@sick.com. Also, take a look at our traffic sensor brochure for more information!