Technical Comparison of Commercially Available Trams and Review of Standardization Frame and Design Principles

Tram manufacturers have different ways of approaching the design of low-floor trams with compact and reliable running gears, and therefore several tram architectures can still be found. A complete standardization of trams is nearly impossible, and technical innovations can be more easily introduced if compared to conventional railway vehicles, but the trend towards large-scale standardization based on vehicle “platforms” can be seen in recent years. However, the current “standard” tram architecture, which includes only non-pivoting bogies, is not able to solve some typical problems of tram operations, such as high wheel and rail wear and high-pitched tonal noise (squeal) in sharp curves, which are described in the present paper. This research analyses the tram market with the aim of describing the state of the art of currently available products and comparing their main technical parameters. The analysis is based on information available from the literatures (journals, web) where data about the vehicles can be found, while a new designation code (tram architecture designation, TAD for short) is specifically introduced for easier identification of the different tram architectures. Even if the complete low floor is still one of the main requested features, several solutions combining pivoting and non-pivoting bogies are commercially available, showing a tendency to give more relevance to running quality performance with respect to the recent past.