The public transport company Consorzio Trasporti e Mobilità (CTM) in Cagliari has released a 4.5 km long line extension of its electric bus system without overhead contact line along the coast. Vossloh Kiepe and Van Hool delivered 14 electric dual-mode buses. Four of them have been equipped with the powerful lithium-titanate-oxide (LTO) batteries. These batteries are charged when the buses are operated via the overhead contact line (in-motion charging - IMC) or at the terminal in the form of opportunity charging.
The electric bus with LTO battery for IMC is 12 metre long and can transport 85 passengers plus the driver. Thanks to the usable energy of the LTO batteries of more than 18.5 kWh and a peak power of 120 kW the buses can also accelerate powerfully in the sections without overhead contact line. Therefore, they can easily be operated fully without overhead contact line in both directions of the line extension, i.e. altogether over a length of 9 kilometers.
The opportunity charging at the terminal during the driver’s break prolongs the life time of the batteries because they are discharged to a lesser degree. The IMC trolleys are used for the opportunity charging as they can automatically dock into the funnels of the charging station. Moreover, the buses have been equipped with AC charging plugs so that they can be charged in the depot when they are serviced. Generally, the batteries are charged during the journeys under the overhead contact line so that the electric buses return to the depot with fully charged batteries in the evening.
This kind of line extension is a novelty and has been realised within the scope of the European research project ZeEUS (Zero Emission Urban Bus System) coordinated by the UITP (International Association of Public Transport).
