Norway is able to present an excellent track record over the last 25 years when it comes to tunnel safety. Norwegian traffic authorities are constantly investing in the latest technologies and are improving the way tunnel safety is handled with every new tunnel construction or refurbishment.
When the Knappe Tunnel, part of County Road 557 near Bergen, needed an upgrade, the Norwegian traffic authorities seized the opportunity to equip the tunnel with the latest safety technology and assure travellers of the highest level of security.
The Knappe Tunnel is a four-lane, twin-tube motorway tunnel, part of the FV557 Ringway West, which is a new roadway connection southwest of Bergen in the Hordaland area. The Ringway West was developed to tackle the region’s increasing congestion problems. The first part of the Knappe Tunnel is 2.6km-long and runs from Dolvik (under the Søreide and Nordås waterways) to Sandeide and one direction lane to Straume.
The second section is 2.8km-long and runs north towards Liavetnet, making the total length from Dolvik to Liavetnet 5.4km. The exiting left lane of the Knappe Tunnel leads directly to the slip road into the Lyderhorn Tunnel, which is 1.2km-long.
Automatic incident detection
Nordic system integrator Trafsys has been active in the region for more than 25 years and has delivered solutions for hundreds of complex traffic system installations in tunnels and on roads. Trafsys was contracted by the Norwegian traffic authorities to supply a wide range of tunnel systems, including traffic management, SCADA, radio, emergency roadside phone, and communications network. For the tunnel’s Automatic Incident Detection system, Trafsys relied on FLIR Intelligent Transportation Systems to deliver the dedicated AID camera technology.
“We chose FLIR as our partner because that company has a proven track record when it comes to supplying tunnels with video-based incident detection technology,” says Knut-Olav Bjelland, Department Manager at Trafsys, AS.
“We are also convinced that FLIR’s AID cameras are the most efficient way to provide 24/7 safety monitoring and incident detection in a complex tunnel structure like the Knappe and Lyderhorn tunnels.”
Thermal and visual cameras for tunnel exit and entrance
At the entrance and exit of the Lyderhorn Tunnel, Trafsys also installed FLIR’s ITS Series Dual AID cameras, which combine best-in-class thermal and visual imaging technology with advanced video analytics. The addition of a thermal camera is ideal for tunnel entrances and exits because shadows or direct sunlight could obstruct a visible-light camera view and disturb traffic detection. Thermal cameras, however, have no issues with these phenomena and can detect traffic 24/7 in all weather conditions.
Network box camera
Trafsys opted for 282 units of the FLIR TrafiBot, a network box camera that provides superior image quality, embedded incident detection analytics, as well as multi-stream encoding. TrafiBot is able to generate traffic data and incident detection information to support traffic operators with alerts on stopped vehicles, wrong-way drivers, pedestrians, lost cargo, smoke, and traffic flow data.
One of the strengths of FLIR’s TrafiBot camera convinced Trafsys with its embedded intelligence. Through this capability, a decentralized architecture with intelligence located ‘on the edge of the network’ becomes possible. As the TrafiBot camera takes care of all the processing, the video stream does not need to be sent over the network to a central processing server. This significantly reduces network traffic. In fact, there is no traffic as long as nothing relevant is being detected by the camera.
Flux video detection management
All traffic data, events, alarms, and video images generated by the TrafiBot cameras are collected by seven FLUX video detection servers. FLUX is FLIR’s dedicated video detection software platform that offers video management capacity and can control network video recorders, video walls, mobile, and fixed cameras. In this case, the FLUX servers are directly interfacing with the SCADA system of Bergen’s central traffic management centre.
When an incident of any kind is picked up by the FLIR cameras, a message will pop up on the video wall in Bergen, which makes it possible for control room operators to take the appropriate emergency response measures.
Triggering third-party systems
At the same time, the video detection systems from FLIR will trigger other traffic control systems via the SCADA system. For example, the detection of wrong-way drivers will automatically activate the closure of the left lane and, by extension, the whole tunnel complex. Current tunnel drivers then are forced to take the right lane and reduce speed to 60km/h. When queues are detected, then the VMS signs will display a warning to motorists.
Incidents of stopped vehicles are visually evaluated by a control room operator and do not automatically activate another traffic control system. Thanks to its high image quality, the TrafiBot camera offers a reliable reference for control room operators.
Through network communication, the operation of the TrafiBot cameras can be controlled remotely from the control room. This can be very useful in cases where the incident detection functionality needs to be deactivated during tunnel maintenance operations in order to avoid false alarms.
“So far, the feedback of control room operators and of the tunnel operators, in general, have been nothing but positive,” says Knut-Olav Bjelland. “Tunnel incidents are being detected by the TrafiBot cameras within seconds and the rate of unwanted alarms is at a very low and very workable level.”
Jan Trygve Totland, Technical Manager at the road traffic centre in Bergen says: “The AID system in The Knappe Tunnel is working very well, autonomously. We have had several cases with wrong way drivers that were detected by the system. In some of the cases, the driver was driving in the wrong direction for the entire length of the tunnel. On the recorded video, we can see that the system is working as planned. We are quite sure that the AID system and automatic reactions in the control system have prevented accidents in the tunnel.”