Smoke tests as the basis for precise fire protection in existing stock
What at first glance resembles a prank by a group of teenagers is in reality high-precision engineering: using a fog simulation, real-world smoke tests were carried out in double-decker carriages in Graz – a crucial milestone for the modernisation of older, still-serviceable rail vehicles.
The starting point: existing vehicles meet modern requirements
Graz-Köflacher Bahn und Busbetrieb GmbH (GKB) plans to modernise 21 former double-decker vehicles built in 1994 (DoSto94) by Deutsche Bahn and deploy them on the Austrian rail network in future. As the routes include sections with tunnels, current safety requirements of the TSI SRT and EN 45545-1 tunnel directives must also be taken into account. The vehicles, which are around 30 years old, are naturally not designed to meet these standards. This is where FOGTEC’s Smart Concept comes into play. A well-thought-out fire protection concept which, through the use of various fire detection components, renders extensive structural measures obsolete.
Challenge: Complex air flows in double-decker carriages
Double-decker vehicles place special demands on fire detection. Air flows are not linear but are distributed across several levels, stairwells and technical zones.
Standardised placement of smoke detectors quickly leads to inefficient solutions here, either with too many components or with insufficient detection reliability.
Solution: Real-world smoke tests with stage fog
To manage this complexity, extensive smoke tests were carried out on-site in Graz. Using small chimneys and artificial fog, real-world flow scenarios were simulated and made visible.
On this basis, the flow paths were analysed and critical detection points identified. This enabled the number and position of the detectors to be determined precisely.
The result is an engineering-optimised solution that avoids excessive oversizing whilst ensuring reliable early detection.
Safety concept: Early detection instead of emergency stops in the tunnel
As operational safety in the tunnel is a central aspect of the project, the objective is to ensure that the train does not come to an immediate halt in the event of a fire.
FOGTEC’s Smart Concept enables early warning of train crew, allowing the train to continue in a controlled manner to the next safe stopping point outside the tunnel.
In this way, the fire detection system makes a significant contribution to evacuation safety and operational continuity.
Systems and services provided
Based on the analysis, different components are installed in the various areas of the vehicle:
Passenger compartments and toilet areas are equipped with smoke and multi-criteria detectors fitted with acoustic sounder bases.
Multi-criteria detectors detect both smoke and temperature and trigger an alarm as soon as predefined thresholds are reached or exceeded.
The technical areas, in particular the on-board inverters, are equipped with thermal fire detection via heat detection cables (LHD) as well as self-contained aerosol generators for active fire suppression.
The double-decker carriages are each fitted with a Control Power Unit (CPU) from the FOGTEC 3000+ series. Their relay modules transmit the alarm signals from the detectors directly to the train driver via the vehicle’s own UIC line.
Conclusion: Precision rather than a one-size-fits-all solution
The project demonstrates that modern fire protection concepts in existing infrastructure require one thing above all else: a deep understanding of the actual conditions.
The cold smoke tests were not merely a visual experiment, but the basis for an economically and technically optimised solution.
In this way, an older existing vehicle is transformed into a standards-compliant, future-proof system for use on the Austrian rail network, without unnecessary modifications but with maximum safety.
