About the project
BERNMOBIL, the municipal transport company of the city of Bern, operates both a tram and a bus network in the city. The network is operated with a fleet comprising diesel, gas, electric and trolley bus vehicles.
The city of Bern, as the owner of BERNMOBIL, has set themselves the target that by 2040, the operation of all local transport lines must be carbon neutral, or carbon emissions must be reduced as far as is reasonably practicable. From 2025, only emission-free vehicles are to be procured. The vehicles currently used on bus line 10 (Bern – Köniz – Schliern) will reach the end of their service life in 2024/2025 and are therefore affected by this requirement.
Enotrac’s responsibility as part of the project team, which consisted of transport planners, civil engineers and electrical engineers, was for traction and electrification. Initially, in a basic study commissioned by the Canton of Bern and the Regional Conference Bern-Mittelland (RKBM) together with the City of Bern, the municipality of Köniz and BERNMOBIL, suitable solutions with regard to the traction concept and vehicle size for this line branch were determined.
The following drive concepts were considered:
- E-bus night charging at a line-independent location (e.g. garage/depot)
- E-bus with charging station at the terminal stop
- E-bus with en route fast chargers at stops (intermediate charging stations)
- Trolleybus with partial overhead line
The trolleybus with partial overhead contact line was identified as the most promising solution, which is where part of the route is equipped with a catenary system, and for the remaining part of the route the bus is powered by battery.
Subsequently, three feeding variants identified in the initial basic study were examined in detail by the Enotrac experts using FABEL simulations. The three variants differed in the degree of electrification, i.e. in the length of the overhead line, and in the number and location of rectifiers and charging infrastructure. For the investigation, a model of line 10 from Bern railway station to Köniz Schliern was developed for dynamic load flow calculations. This model was then used to simulate various network switching and operating scenarios. Using these simulations, the energy storage dimensions, the voltage stability along the electrified line sections, the load on the rectifier systems and charging infrastructures as well as on the feeder and return cables and overhead line system were determined. Based on these results, the planning of a feeding variant to be effectively implemented could be started.
The study was also presented at the dcrps conference 2022 in Leipzig.
2020 – 2026
Our services in the project