As in many other cities around the world, trolleybuses have been outdated since decades – the last traditional trolleybuses ran in West Berlin in 1965 and in the eastern part of the city in 1973.
But now a comeback is looming: As Berlin’s public transport operator BVG is preparing to electrify its bus fleet until 2030, the partial installation of trolleybus overhead lines is planned for the trunk lines of the network in Spandau. Under the slogan “as much as necessary and as much as possible”, the partial electrification with catenary represents the economical optimum between re-charging infrastructure and batteries.
The plan is that battery-hybrid-trolleybuses will run under catenary 50 – 65 % of the respective routes in order to re-charge the traction batteries. The rest of the line will be operated in battery mode. This principle is also called “In Motion Charging” (IMC) in other cities. Apart from economical benefits, the catenary allows to charge while driving and therefore has no impact on timetable or the fleet size due to long recharging times at the terminus. The combination of catenary and batteries also allow for higher ranges and larger bus units such as bi-articulated buses.