Simulation Finding the best escape route from underground train stations
Simulations should be able to predict which escape routes are safe in the event of a fire or poison gas attack quicker than in real time. However, the natural air flows first need to be known.
A new method for measuring natural air flows in underground train stations is being developed by Markus Brüne at the Ruhr-Universität Bochum. He is participating in the Orpheus project, which is investigating the safest way for people to exit an underground train station in the event of an emergency situation. A computer model is being developed for this purpose that should one day be able to predict quicker than in real time how poisonous gas or smoke spreads in a train station and where the safety escape route is. To ensure that the simulation correctly reflects real life, the natural air flows in an underground train station need to be taken into account. Markus Brüne explains how they can be measured in the science magazine Rubin published by the Ruhr-Universität Bochum.
The Federal Ministry of Education and Research funded the project “Optimization of smoke management and evacuation strategies in underground train stations: experiments and simulations”, in short Orpheus, from February 2015 to February 2018. The project coordinator is the Forschungszentrum Jülich.
Air flows change over time
Every underground train station has its own climate: The air flows are dependent on the structural features and external weather conditions. To ensure that the computer model can make realistic predictions for a particular station, it is necessary to know the underlying conditions, i.e. the air flows, in the station.
Researchers measure air flows in experiments using special devices, so-called ultrasonic anemometers. However, this approach would be too time consuming and expensive for everyday application.
Measuring the temperature using communication cables
Markus Brüne thus followed a different approach during his doctoral studies in the Working Group Climatology of Extreme Locations. He investigated whether air flows could be derived from temperature measurements. The temperature could in turn be measured via fibre optic cables – numerous cables of this type are already installed in underground railway tunnels.
“The Communication cables in subway systems consists of optical fibre cables,” explains Markus Brüne to describe the concept. “We are investigating whether these already existing fibre optic cables can be used to measure the temperature.” This was one of the questions that was the focus of Brüne’s work in the Orpheus project. He recorded the data at the “Osloer Straße” underground train station in Berlin.
Slow but correct
As a control, he also measured the temperature in the same train station using a fibre optic cable specially installed for the experiment and using standard temperature sensors. The results are promising according to Markus Brüne. “The communication cable is slow”, he reports. “There is a time delay of five to ten minutes compared to special sensor cables.” Yet the cables do provide correct information about slow changes in temperature and should, in his considered opinion, be sufficient for normal air flow measurements.
Markus Brüne will now test whether air flows can be reliably recreated from the temperature data.