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Smoke in the tunnel: Bonn City Council simulates fire in Godesberg

Smoke in the tunnel : Bonn City Council simulates fire in Godesberg

The Bonn City Council ignited a fire in the Bad Godesberger Tunnel and simulated an emergency there. Special systems were tested this way, which extract smoke from the tunnel tube at lightning speed in the event of an accident.

The smoke spreads rapidly. In the distance a fire blaze is clearly visible. On the walls of the Godesberg tunnel very bright white lamps flash again and again as a warning. The escape route is marked with green symbols. Meanwhile, the smoke rises to the ceiling of the tunnel and is sucked into a five square metre recess. In the area there, vortices of air are created which are clearly visible through the smoke. The area where drivers are usually located is smoke-free. A ghostly picture was drawn during a big test in the Bad Godesberger Tunnel late on Tuesday evening.

But it was not without reason that the city of Bonn lit a fire in the heavily frequented road tunnel: The new smoke extraction system of the Bad Godesberg Tunnel was extensively tested, and the fire test was also part of the acceptance test of the new safety technology. The building is currently undergoing extensive safety refurbishment. "20 years ago, fire protection was state-of-the-art, but now some parameters have changed following tunnel accidents," explained Stefan Pieper, Head of Department at the Civil Engineering Office, to the GA. He is also the project manager for the more than ten million euro renovation project. The tunnel on the Rhine side has now been completed and could therefore be subjected to the large-scale test.

A Czech specialist company had lit the fire in the middle of the tunnel to check whether the new safety systems were working. Sensitive technology was previously secured separately so that it could not be damaged during the test, which produced smoke and heat.

As soon as the fire was ignited by the experts around 23 o'clock, the security systems intervened. The previously very finely tuned sensors and a special fire alarm cable, which is now installed in the entire tunnel tube, reported the development of heat and smoke. "The fine adjustment is enormously important, because it would not be purposeful, if the system seized for example with an older truck, only because it’s very smoky. Detection is a problem," says Pieper. After the tunnel sensors detected the smoke and heat, an alarm was immediately sent to the Bonn fire brigade and the tunnel was closed - the scenario worked.

Seconds after the smoke spread, one of the new dampers, which resemble venetian blinds, opened. "For these dampers, the ceiling had to be opened and statistically reinforced," said Pieper. The special flap ensured that the smoke was sucked in quickly, so that the area occupied by the people present remained smoke-free. This is extremely important in an emergency, because only in this way can drivers orient themselves to the new lighting system and find the emergency exit. This is always supplied with fresh air by a sophisticated system. In addition, toxic gases are diverted directly through the intake system. One such fume hood is now located in the tube every 100 metres - 15 in all. Huge turbines also supply the tunnel tube with air or ensure the extraction of used air. The output of the huge fans is over 65 cubic meters of air per second. Thanks to the new technology, the smoke can now be very precisely discharged at a fire point and the fire can be located. "The test was absolutely successful," Stefan Pieper told the GA.

For the test, which was accompanied by an expert, the Bad Godesberg road tunnel was fully closed to traffic on Tuesday evening at around 9 pm. Around five o'clock on early Wednesday morning, traffic was due to flow through the tunnel normally again. The uphill tunnel is still closed as it is currently being modernised. However, the construction work there should also be completed by the end of the year.

(Original text: Maximilian Mühlens; Translation: Mareike Graepel)