This weekend is a great train show at the trainyard Heddernheim of the U-Bahn Frankfurt to celebrate the 50th anniversary of the U-Bahn.

An U-Bahn car of the U4 series. These traoin were introduced in 1994 and are still in service today. A derivative of the U3 series (called U3-2000 at one point of their development), they are prone to technical problems. I don´t like using them.