Development of a new hybrid bus for urban public transportation

Nowadays the increasing demand for sustainable mobility has fostered the introduction of innovativepropulsion systems also in the public transport sector in order to achieve a significant reduction of pol-lutant emissions in highly congested urban areas. This paper describes both the design and the optimiza-tion of an environmentally friendly hybrid bus (hereafter referred to as ‘‘HYBUS’’) for urban publictransportation.After a preliminary description of the main features of the hybrid architecture, this paper assessed,through numerical simulations, the fuel economy potential of the hybridization in real world driving con-ditions. The promising results of this first part of the study led to the development of a first prototype.The first prototype of the bus was built by integrating an innovative hybrid propulsion system featuringa plug-in series architecture into the chassis of an old IVECO 490 TURBOCITY. The bus is 12 m long andcapable to host up to 116 passengers in the original layout. The project relied on a modular approachwhere the powertrain could be easily customized for size and power, depending on the specific applica-tion.The prototype was then extensively tested in the city of Genoa, Italy, an urban context extremelychallenging for a hybrid powertrain due to its frequent uphill routes and significant road grades. The out-comes of the test campaign confirmed the simulations forecasts, and fostered additional analysis aimedto optimize the energy management strategy of the hybrid powertrain.Numerical simulations were then used in order to identify more refined energy management strategiescapable of further enhancing the fuel economy potential of the hybrid architecture. Consequently, a novelenergy management was developed, and virtually tested, to manage the HYBUS in a more effective way.The results demonstrated the interesting potential of such hybrid architectur