Bern boasts a well-developed and frequent bus network that covers a significant portion of the region’s public transport needs. Numerous bus routes connect central urban areas with suburbs and more rural communities, ensuring mobility for commuters, students, seniors, and anyone who relies on dependable connections. Bernmobil’s fleet is continuously expanding – particularly through the integration of modern electric and hybrid buses – to meet the growing demands for climate protection, sustainability, and reliable transport services. The iconic red buses are an integral part of Bern’s cityscape.
In this context, effective fire protection is of paramount importance: the electric buses and charging infrastructure must be secured around the clock to ensure smooth and low-risk operation, even at night or during peak traffic hours. Our high-pressure water mist system ensures the reliable protection of Bern’s public transport fleet, allowing residents and commuters to continue reaching their destinations safely and on time.
The bus depot in Bern was expanded with several electric and hybrid buses as part of the increasing electrification of public transport. Due to the altered fire trajectory of modern vehicles and the limited space within the depot, a highly effective, technical fire suppression system was required to reliably protect both conventional buses and e-buses with lithium-ion batteries.
FOGTEC implemented a high-pressure water mist (HPWN) system for the depot, based on the results of the SUVEREN_4_Depots research project. The system was designed to replicate the typical operating conditions of a bus depot—including close vehicle parking, e-buses with batteries in the underbody or on the roof, and any charging infrastructure.
Technical Implementation
- The HPWN system operates at a pressure of 70 bar, producing finely atomized water droplets with a large surface area—ideal for rapid and efficient cooling.
- The very fine water mist atomization allows for a high cooling effect with minimal water consumption. This reduces the requirements for firewater retention and enables more compact pump rooms, even when retrofitting existing systems.
- The system is designed for heat release rates of up to approximately 35 MW, corresponding to the maximum assumed fire output of modern electric buses, including the battery.
- The system is designed to prevent fire spread to neighboring vehicles, ensure building protection (roof and wall structure), and enable effective firefighting by emergency personnel.
