Following on the (w)heels of our interesting recent AP wheel design thread, here's a UK application.

"Train wheels run on top of raised rails and rarely have to make tight corners. Tram tracks are often flush with street surfaces, so the wheels are designed to ride inside the grooves. And trams are also expected to make hairpin turns. Put the wrong kind of wheels on the wrong kind of track, and you’ll derail, especially at junctions or corners.

A special wheel design that takes into account both setups is a key part of the Sheffield tram-train. Developed at the University of Huddersfield’s Institute of Railway Research, it gives special consideration to worn rails and wheels."

The wired article ends with a reference to the “Karlsruhe model.”